(PDF) Impact of heavy resistance training on pregnancy and postpartum health outcomes

Vol.:(0123456789)

1 3

International Urogynecology Journal (2023) 34:405–411

https://doi.org/10.1007/s00192-022-05393-1

ORIGINAL ARTICLE

Impact ofheavy resistance training onpregnancy andpostpartum

health outcomes

ChristinaPrevett1· MirandaL.Kimber2· LoriForner3· MarlizedeVivo4· MargieH.Davenport2

Received: 4 August 2022 / Accepted: 6 October 2022 / Published online: 4 November 2022

Abstract

Introduction and hypothesis Participation in Olympic weightlifting, the Valsalva maneuver, and acute or prolonged supine

weightlifting during pregnancy are cautioned against; however, these recommendations are based on expert opinions as

opposed to empirical evidence. The aim of this study was to examine the training and health outcomes of individuals who

engaged in heavy resistance training during pregnancy.

Methods A total of 679 individuals who lifted at least 80% one-repetition maximum during pregnancy participated in an

online survey.

Results Participants were primarily recreational athletes (88%, 332 out of 675) engaged in CrossFit™ (61%, 410 out of 675)

and/or weightlifting (49%, 332 out of 675) during pregnancy. Most participants reported no complications during pregnancy

or delivery (66%, 388 out of 589), whereas 57% (241 out of 426) reported urinary incontinence following pregnancy. Par-

ticipants who maintained pre-pregnancy training levels until delivery reported signiﬁcantly less reproductive complications

than those who ceased training levels prior to delivery (p = 0.006). Most respondents engaged in Olympic lifting (72%, 311

out of 432) and lifting in a supine position (71%, 306 out of 437), whereas fewer reported use of the Valsalva maneuver

during pregnancy (34%, 142 out of 412). Most returned to weightlifting following delivery (89%, 400 out of 447, average:

3.2 ± 3.0 months), including Olympic lifting (81%, 300 out of 372, average: 4.0 ± 3.4 months) and Valsalva (62%, 213 out

of 341, average: 4.5 ± 3.6 months).

Conclusions Individuals who engaged in heavy prenatal resistance training had typical perinatal and pelvic ﬂoor health

outcomes that were not altered whether they engaged in, or avoided Olympic lifting, Valsalva or supine weightlifting.

Keywords Weightlifting· Prenatal· Postnatal· Valsalva· Olympic weightlifting· Supine weightlifting

Introduction

Female participation in strength-focused sports such as

CrossFit™, weightlifting, and powerlifting has risen dra-

matically over the last decade [1, 2]. Owing to a lack of data

supporting safe participation in heavy/strenuous weightlift-

ing, prenatal physical activity guidelines discourage Olym-

pic lifting, Valsalva maneuver, and acute and/or prolonged

weightlifting in the supine position [3–6]. However, these

recommendations are largely based on expert opinion as

opposed to empirical evidence.

Traditionally, pregnant individuals were discouraged

from engaging in heavy lifting based on evidence in an

occupational setting where repetitive lifting more than

11 kg was associated with an increased risk of having a

miscarriage, developing preeclampsia, or having a pre-

term delivery [3, 7]. However, occupational lifting and

* Margie H. Davenport

mdavenpo@ualberta.ca

1 Institute ofClinical Excellence, Concord, NC, USA

2 Program forPregnancy andPostpartum Health, Physical

Activity andDiabetes Laboratory, Faculty ofKinesiology,

Sport andRecreation, Women andChildren’s Health

Research Institute, Alberta Diabetes Institute, University

ofAlberta, Edmonton, Alberta, Canada

3 The University ofQueensland, Brisbane, Australia

4 Active Pregnancy Foundation, Canterbury Christ Church

University, Canterbury, UK

406 International Urogynecology Journal (2023) 34:405–411

1 3

heavy weightlifting in a recreational setting are vastly

different and cannot be equated to establish the potential

for adverse pregnancy outcomes. In recreational settings,

dynamic movements at intensities to improve metabolism

typically occur over a short period of time (<60 min), and

allow sufficient time to recover. In contrast, chronic phys-

ically demanding activities in an occupational setting gen-

erally do not include sufficient rest or recovery and may

induce physiological “overtraining,” fatigue, psychologi-

cal stress, and detrimental health effects [8]. Further, con-

cerns of excessive stress on the pelvic floor from heavy

weightlifting also inspire recommendations to avoid these

activities during pregnancy. Evidence demonstrates that

nonpregnant female athletes who participate in powerlift-

ing, CrossFit™, and weightlifting have a higher incidence

of stress urinary incontinence (UI) during heavy lifting

and high-impact activities [9–12]. During pregnancy, up

to 75% of pregnant individuals experience UI prior to

delivery [13] and the combination of heavy weightlifting

and pregnancy could exacerbate the risk of UI. However,

the combined impact of pregnancy and heavy weightlift-

ing on UI is unknown.

Prenatal physical guidelines recommend avoiding the

Valsalva maneuver owing to concerns surrounding the

substantial, but transient, increase in maternal blood

pressure. Two studies have demonstrated that the Vals-

alva maneuver during pregnancy is not associated with

any adverse acute maternal outcomes [14, 15]; however,

both were completed at relatively low training loads (up

to a maximum of 50 lb [22.68 kg] with incline bench

press [14] and 40% of ten-repetition maximum [RM] in

a seated leg press) [15]. Acute and/or prolonged supine

exercise, particularly after 16 weeks of gestation, has

been cautioned against for decades [16]. Evidence has

demonstrated that supine positions during pregnancy

compress the maternal inferior vena cava (IVC) and aorta,

which may result in maternal hypotension and reduced

fetal oxygenation [17–19]. A recent review observed that

despite compression of the IVC in the supine position,

the majority of pregnant individuals do not demonstrate

symptoms of hypotension [20]. At this time, evidence

remains inconclusive whether acute or prolonged supine

exercise during pregnancy is associated with adverse out-

comes [21, 22].

Given the distinct lack of empirical evidence support-

ing (or not) the safety of heavy weightlifting (includ-

ing supine and Olympic weightlifting) and the Valsalva

maneuver, the aim of the present study was to examine

whether women who continued to participate in heavy

resistance training during pregnancy (>80% 1repeti-

tion max[RM]) were at a heightened risk for adverse

birth outcomes, adverse fetal outcomes, or pelvic floor

dysfunction.

Materials andmethods

Survey

The questionnaire was developed by pelvic ﬂoor physi-

otherapists (C.P., L.F.), exercise physiologists (M.H.D.,

M.K.), a biokineticist and sports rehabilitator (M.D.), and

an elite-level weightlifter (C.P.) from Canada, the USA,

Australia, and the UK. The public was not involved in the

design of this study. The survey was piloted with a small

group of female athletes to assess the feasibility, usability,

and clarity of the survey. The questionnaire consisted of

60 questions and took 20–30 min to complete. Question

domains included maternal demographics, sport history,

reproductive history, pregnancy health outcomes, and pre-

pregnancy/pregnancy/postpartum aerobic and resistance

training characteristics. Respondents were asked about any

signs or symptoms of pelvic ﬂoor dysfunction (leaking,

heaviness, symptoms of prolapse, pain) during and fol-

lowing pregnancy. Finally, participants were asked about

information sources that they used to make decisions about

heavy weightlifting during pregnancy.

Participants

Between 14 June and 21 August 2021, we recruited 679

participants through social media (e.g., Instagram), word

of mouth, and through the authors’ personal networks. Par-

ticipants had to be over the age of 18 and engaged in heavy

weightlifting during pregnancy (>80% 1RM). A threshold

of greater than 80% was chosen as this exceeds any cur-

rent resistance training literature in pregnant individuals and

equates to loads higher than published guidelines have rec-

ommended owing to a paucity of literature [4–6]. Electronic

informed consent was provided before completing an online

survey. This study was approved by the University of Alberta

Health Research Ethics Board (Pro00109302) and was con-

ducted in accordance with the Declaration of Helsinki, apart

from registration in a publicly available database. Responses

were collected through Research Electronic Data Capture,

a web-based software hosted by the Women and Children’s

Health Research Institute, University of Alberta, Canada.

Statistical analysis

After all the responses were collected, all data were cleaned

and verified for accuracy, and impossible (e.g., nonhu-

man body weight) data were removed. All exclusions were

reviewed by M.K. and M.H.D and discarded following con-

sensus. The mean ± standard deviation was calculated for

407International Urogynecology Journal (2023) 34:405–411

1 3

continuous variables, and frequency of responses (n and %)

were calculated for categorical variables. Subgroup analysis

comparing training patterns and/or pregnancy outcomes of

pregnant individuals:

1. With and without UI

2. Who performed Valsalva during pregnancy

3. Who engaged in supine lifting during pregnancy

4. Who engaged in Olympic lifts during pregnancy

To determine diﬀerences between groups, Fisher’s exact

tests were used for categorical data, and multiple t tests

using the false discovery rate were used for continuous data.

Odds ratios with 95% conﬁdence intervals (95% CI) were

calculated for all categorical variables.

Results

Participant characteristics

Participant demographics are provided in Table1 of the Sup-

plementary Material. Most respondents were recreational ath-

letes (88%, 594 out of 675) who had been engaged in heavy

weightlifting for 6.7 ± 4.1 years (range 1–30). Participants

reported lifting at least 73% of their pre-pregnancy body

weight during pregnancy (snatch, 73%; bench press, 85%;

clean and jerk, 94%; clean, 97%; squat, 133%; deadlift, 163%).

Reproductive outcomes

Pregnancy or delivery complications were reported by 34%

of respondents during (201 out of 589), and 20% (112 out of

574) following pregnancy (see Supplement Digital Content

Table2 for the full list of complications). Rates of gestational

hypertension (18 out of 589, 3%), preeclampsia (17 out of

589, 3%), and gestational diabetes mellitus (4 out of 589,

1%) were below expected prevalence values for the general

obstetrical population. Prevalence of pregnancy and delivery

complications were largely not diﬀerent between respond-

ents who engaged in Olympic lifting, Valsalva maneuver, or

supine exercise, compared with those who did not (see Sup-

plementary Tables3, 4, and 5). Respondents who maintained

pre-pregnancy training levels until delivery reported signiﬁ-

cantly less pregnancy and delivery complications than those

who reduced their training level prior to delivery (OR: 0.49,

95% CI, 0.29–0.81, p=0.006; see Supplementary Table6).

Training patterns duringpregnancy

During pregnancy, 85% of respondents continued to engage

in heavy weightlifting (with or without modiﬁcation) until

delivery, including 24% (108 out of 445) who maintained

their pre-pregnancy training levels throughout gestation

(see Supplementary Table7). The majority of participants

engaged in Olympic weightlifting (72%, 311 out of 432)

and supine weightlifting (71%, 306 out of 437) during preg-

nancy, whereas a minority of individuals reported perform-

ing Valsalva maneuvers during pregnancy (34%, 141 out

of 420).

Urinary incontinence

Thirty-seven percent of participants experienced UI during

pregnancy. Individuals who experienced prenatal UI had a

lower 1RM for squat, bench press, clean, and clean and jerk

prior to conception (see Supplementary Material Table8).

However, all other variables, including pre-pregnancy and

pregnancy training volumes, and engagement in Olympic

lifting, Valsalva, and supine exercise, were not diﬀerent

between individuals who did and those who did not maintain

continence during pregnancy (see Supplementary Material

Tables8 and 9).

Olympic weightlifting, Valsalva, andsupine exercise

Respondents who engaged in Olympic weightlifting during

pregnancy had a signiﬁcantly higher pre-pregnancy 1RM for

all six lifts, as well as duration and frequency of weightlift-

ing sessions (see Supplementary Material Table10). During

pregnancy, participants who engaged in Olympic lifts were

more likely to perform the Valsalva maneuver (OR: 2.12,

95% CI, 1.29 to 3.39, p=0.003), and reported a greater fre-

quency of resistance training (3.09 ± 1.20 vs 2.55 ± 0.97

days/week; p=0.0007). There were no diﬀerences in the

remaining training outcomes between groups (see Supple-

mentary Material Tables10 and 11).

Respondents who engaged in Valsalva during preg-

nancy had significantly higher pre-pregnancy 1RM for

squat, bench, and deadlift, as well as a higher number of

weightlifting training days per week (4.07 ± 1.08 vs 3.62 ±

1.13 days/week; p≤0.0001), duration per session (60.78 ±

23.13 vs 52.29 ± 18.74 min; p=0.002), and %1RM (77.92 ±

10.07 vs 75.32 ± 10.90 %1RM; p=0.03; see Supplementary

Material Table12). Individuals who performed the Vals-

alva maneuver during pregnancy were more likely to par-

ticipate in Olympic Lifting (OR: 1.98, 95% CI, 1.21 to 3.26,

p=0.006), supine weightlifting (OR: 3.00, 95% CI, 1.80 to

5.02, p≤0.0001) and use of a weightlifting belt (OR: 4.04,

95% CI, 2.08 to 7.67, p≤0.0001). There were no diﬀerences

in any of the other outcomes between groups (see Supple-

mentary Material Tables12 and 13).

Respondents who engaged in supine weightlifting during

pregnancy had higher pre-pregnancy 1RM for all lifts except

for snatch and a greater frequency of weightlifting pre-preg-

nancy (3.90 ± 1.09 vs 3.58 ± 1.19 days/week; p=0.007) but

408 International Urogynecology Journal (2023) 34:405–411

1 3

a lower duration of vigorous intensity aerobic activity prior

to pregnancy (32.82 ± 15.63 vs 36.96 ± 18.57 min; p=0.04;

see Supplementary Material Table14). During pregnancy,

frequency of weightlifting was higher among those who

engaged in supine weightlifting (3.14 ± 1.18 vs 2.52 ± 1.04

days/week; p≤0.0001); however, there were no diﬀerences

in other training variables between groups. Participants

who engaged in supine lifting had a greater prevalence of

engagement in Olympic lifting (OR: 2.01, 95% CI, 1.31 to

3.12, p=0.002), Valsalva (OR: 3.20, 95% CI, 1.93 to 5.32,

p≤0.0001), and use of a weightlifting belt (OR: 2.80, 95%

CI, 1.27 to 6.65, p=0.01). There were no diﬀerences in any

of the other outcomes between groups (see Supplementary

Material Tables14 and 15).

Training patterns followingdelivery

The majority of respondents returned to weightlifting

approximately 3 months following delivery (89%, 400 out of

447, average: 3.15 ± 3.0 months; see Supplementary Mate-

rial Table16). Those who did not return to weightlifting in

the postpartum period reported needing additional time to

recover (40%), not wanting to return (4%), and not having

enough time (23%; see Supplementary Material Table15).

Urinary incontinence

Experiencing UI during pregnancy did not inﬂuence whether

participants returned to weightlifting, or the timing of return

to activity (see Supplementary Material Table17). How-

ever, being continent following delivery was associated with

a 218% increase in the odds of returning to weightlifting

following delivery, compared with those who experienced

postpartum UI (OR: 2.18, 95% CI, 1.16 to 4.14, p=0.02; see

Supplement Digital Content Table18). There were no dif-

ferences in any of the other outcomes between groups (see

Supplementary Material Tables17 and 18).

Olympic weightlifting, Valsalva, andsupine exercise

Respondents who participated in Olympic weightlifting were

more likely to return to weightlifting (OR: 3.61, 95% CI,

1.80 to 7.03, p=0.0004) faster (2.99 ± 2.83 vs 3.73 ± 2.55

months; p = 0.03) than those who refrained from it during

pregnancy. Further, those who engaged in Olympic weight-

lifting during pregnancy were more likely to return to Olym-

pic weightlifting (OR: 3.49 95% CI, 1.96 to 6.11, p≤0.0001)

and Valsalva maneuver (OR: 3.25, 95% CI, 1.91 to 5.55,

p≤0.0001) postpartum, and returned to these activities more

rapidly (p≤0.0001, p=0.01 respectively; see Supplementary

Material Table19). Participants who engaged in prenatal

Valsalva returned to weightlifting sooner after delivery (2.68

± 2.43 vs 3.39 ± 3.23 months; p=0.02) and were 6.33 times

more likely to engage in postpartum Valsalva (95% CI, 3.64

to 10.98, p≤0.0001) than those who avoided Valsalva during

pregnancy (see Supplementary Material Table20). Simi-

larly, participants who engaged in supine weightlifting dur-

ing pregnancy had increased odds of returning to Olympic

weightlifting (OR: 1.86, 95% CI, 1.12 to 3.15, p=0.03) and

Valsalva (OR: 2.03, 95% CI, 1.27 to 3.26, p=0.005) in the

postpartum period (see Supplementary Material Table21).

There were no diﬀerences in any other outcomes between

groups (see Supplementary Material Tables19, 20, 21).

Information sources aboutweightlifting

Responses revealed that most participants spoke to their

healthcare provider about weightlifting during pregnancy

(65%, 278 out of 425) and were told to continue heavy lifting

with modiﬁcation (61%, 169 out of 276) throughout preg-

nancy (see Supplementary Material Table22). Respondents

also sought information from pelvic ﬂoor physiotherapists

(51%, 216 out of 426), the internet (39%, 166 out of 412),

and their coach (27%, 112 out of 412; see Supplementary

Material Table22).

Discussion

Our data demonstrate that individuals who engaged in heavy

resistance training before, during, and following pregnancy,

including “contraindicated” activities, experience low inci-

dence of adverse reproductive and pelvic ﬂoor outcomes.

Rather, perinatal health outcomes aligned with, or were

lower than, population estimates for key health outcomes.

Long-held theoretical concerns about heavy weightlift-

ing, Olympic lifting, supine weightlifting, and the Valsalva

maneuver have limited the prescription of these movements

during pregnancy resulting in a missed opportunity to derive

health beneﬁts from strength training during pregnancy. The

epidemiological data collected do not support several of the

theoretical risks associated with these activities for individu-

als with uncomplicated pregnancies. Prospective studies are

needed to investigate maternal and fetal responses to heavy

resistance training and address concerns of prolonged supine

exercise and overhead Olympic weightlifting.

Contrary to commonly cited theoretical risks of heavy

weightlifting, we demonstrate similar, or lower rates of

pregnancy complications (e.g., preeclampsia, gestational

hypertension) in those who continue to engage in heavy

weightlifting during pregnancy compared with population

estimates [23]. As a key example, we observed substantially

lower rates of postpartum depression and anxiety among this

sample (~7%) compared with general population estimates

(~14%). Our team has previously demonstrated that engag-

ing in postpartum physical activity (e.g., aerobic exercise or

409International Urogynecology Journal (2023) 34:405–411

1 3

yoga) is associated with a moderate eﬀect size on depres-

sive symptoms (standardized mean diﬀerence −0.48, 95%

CI −0.73 to −0.22, I=42%) [24]. The ﬁndings of the current

study are the ﬁrst to illustrate the beneﬁcial impact of heavy

weightlifting on perinatal depression. We also identiﬁed that

individuals engaged in heavy weightlifting during pregnancy

were less likely to report a cesarean section compared with

global rates (13% compared with a global prevalence of

21.1%, 95% conﬁdence interval, 18.8 to 23.3%) [25]. Addi-

tionally, we observed that respondents who continued their

pre-pregnancy training levels until delivery reported signiﬁ-

cantly lower incidence of reproductive complications than

those who reduced or ceased their resistance training levels

during pregnancy. This suggests that engaging in heavy/

strenuous resistance training into late pregnancy might not

increase, or potentially decrease, the odds of reproductive

and delivery complications. The lower prevalence of these,

and other common perinatal complications in pregnant and

postpartum individuals further highlight the urgent need for

further research with this population as current recommen-

dations to avoid these movements may conversely increase

the risk of these complications.

The Valsalva maneuver is a performance aid that

increases stiﬀness across the spine, increases electromyo-

graphic activation of the paraspinal musculature and there-

fore allows for increased loads to be lifted [26]. The Valsalva

maneuver has been ﬂagged as a potential area of concern for

pregnant people owing to the acute and substantial increase

in blood pressure. The present study demonstrates that preg-

nant individuals are largely following this guidance as 66%

of the sample avoided participation. Two previous studies

failed to demonstrate an adverse eﬀect of acute Valsalva

during pregnancy [14, 15]; however, the impact of chroni-

cally engaging in the Valsalva maneuver during pregnancy

has not been investigated. Our data found no diﬀerence in

pregnancy, labor, or delivery outcomes between those who

engaged in the Valsalva maneuver and those who did not.

Similarly, acute and prolonged supine exercise during preg-

nancy is also cautioned against owing to concerns of a tran-

sient reduction in fetal blood ﬂow, and maternal hypotension.

In our sample, there was no diﬀerence in the incidence of

reproductive complications between the 71% of respondents

who engaged in supine exercise during pregnancy and those

who did not. We also observed no diﬀerence in reproductive

outcomes between the 72% of respondents who participated

in Olympic weightlifting and those who did not. Pregnant

individuals may be told to avoid Olympic weightlifting

owing to concerns regarding injury from falling on the stom-

ach, contact with a barbell, or overhead lifting [27]. Among

our sample, there was no diﬀerence in the odds of obtain-

ing an injury both during and following pregnancy between

those who engaged in Olympic weightlifting and those who

did not. Pre-pregnancy 1RM and weightlifting volume were

signiﬁcantly higher among this subsample; thus, experience

and technique may be critical to avoiding injury during preg-

nancy. These data provide preliminary support for the safety

of engaging in Valsalva, supine weightlifting, and Olympic

weightlifting during pregnancy.

Pelvic ﬂoor disorders are common in both female ath-

letes and pregnant individuals [10, 13]. It has been hypoth-

esized that increased intra-abdominal pressure from lift-

ing heavy weights, combined with the Valsalva maneuver

during pregnancy, may further strain the potential weaken-

ing of the pelvic ﬂoor in pregnancy, increasing the risk of

developing or worsening pelvic ﬂoor issues. Although we

saw heightened prevalence of postpartum UI among the

sample (57%), compared with the general population (32%)

[28], this is expected of active women who participate in

high-impact resistance training (41%) [29]. Further, we did

not observe any diﬀerences in training patterns during or

following pregnancy compared with those who remained

continent following childbirth. Similarly, participation in

Valsalva during pregnancy was not associated with greater

odds of UI during or following pregnancy, suggesting that

the increased intra-abdominal pressure from Valsalva dur-

ing pregnancy may not increase risk of UI. However, the

development of UI can be impacted by a variety of factors

including training age, high-impact training (e.g., running),

and obesity may have inﬂuenced these results. Further

research is required to assess the impact of weightlifting

prior to pregnancy and the resultant eﬀects on the pelvic

ﬂoor during and following pregnancy.

Our data demonstrate that the majority of respondents

discussed heavy weightlifting during pregnancy with their

healthcare provider and were most often told to continue

with modiﬁcation. These results demonstrate that pregnant

individuals want to know more about heavy weightlifting

during pregnancy, aligning with recent requests from elite

athletes for more guidance on continuing training during

pregnancy [30]. More research is critically needed to inform

healthcare provider guidance to support individuals who do

not wish to cease their training during pregnancy. Approxi-

mately half of participants reported seeing a pelvic ﬂoor

physiotherapist, most commonly in the postpartum period. A

review demonstrated that pelvic ﬂoor muscle training during

pregnancy signiﬁcantly reduced symptoms and episodes of

UI and decreased prevalence in late pregnancy and 3 months

postpartum [31]. Increased guidance from pelvic ﬂoor physi-

otherapists may be particularly helpful to this population to

help reduce the risk of and treat UI following pregnancy.

Strengths of our study included measurement of reproduc-

tive outcomes during and following pregnancy to assess both

gestational and postpartum impact of participation in heavy

weightlifting. A survey method allowed for the polling of a

large sample size of pregnant individuals from around the

world who participated in heavy weightlifting, improving

410 International Urogynecology Journal (2023) 34:405–411

1 3

the generalizability of our ﬁndings. We also acknowledge

important considerations of the present study. Owing to the

online nature of the study and primary recruitment strategy

using social media platforms, random sampling did not occur,

thus introducing a sampling bias that may have contributed

to some of our ﬁndings. In addition, as this was a cross-sec-

tional survey study with self-reported outcomes, recall bias

will have been introduced into this study. Thus, results from

this survey should be interpreted with consideration of these

limitations. Future longitudinal studies assessing the acute

and chronic eﬀects of heavy resistance training in those who

engaged in these activities prior to pregnancy compared with

those who discontinued training are needed.

This cross-sectional survey did not identify evidence of

adverse pregnancy or delivery outcomes by engaging in heavy

weightlifting, Olympic weightlifting, Valsalva maneuver, or

supine weightlifting during pregnancy. In fact, a lower preva-

lence of common perinatal complications in pregnant and post-

partum individuals was observed, with those who continued

participation until delivery experiencing fewer complications

than those who did not. Our ﬁndings demonstrate that incidence

of postpartum UI was heightened among our sample compared

with the general population; however, this is expected of active

women who participate in high-impact resistance training.

Collectively, these data challenge numerous theoretical risks

of participation in resistance training during pregnancy and

establish the preliminary safety of Olympic weightlifting, Vals-

alva maneuver, and supine weightlifting during pregnancy. It is

important to note that all survey participants were experienced

in heavy resistance training during pregnancy, and the impact

of the uninitiated beginning these activities during pregnancy is

unknown. These data highlight the critical need for more data

to help establish the safety and potential beneﬁt of resistance

training during pregnancy, to challenge persistent myths, and

to improve prescription of these activities during pregnancy.

Additional longitudinal work evaluating the long-term impact

of heavy resistance training on pelvic ﬂoor health are warranted.

Supplementary Information The online version contains supplemen-

tary material available at https:// doi. org/ 10. 1007/ s00192- 022- 05393-1

Author contributions C. Prevett: survey creation and manuscript writ-

ing; M.L. Kimber: survey development on REDcap, data analysis, and

manuscript writing; L. Forner: survey creation and manuscript writing;

M. de Vivo: survey creation and manuscript writing; M.H. Daven-

port: survey creation, survey development on REDcap, and manuscript

writing.

Funding M.H.D. is funded by Christenson Professorship in Active

Healthy Living. M.L.K. is funded by the University of Alberta Fac-

ulty of Kinesiology, Sport, and Recreation Human Performance Fund.

There were no other funding sources.

Declarations

Conflicts of interest None.

References

1. Huebner M, Meltzer D, Perperoglou A. Strength in num-

bers Women in Olympic-style weightlifting. Significance.

2021;18(2):20–5.

2. Huebner M, Perperoglou A. Sex diﬀerences and impact of body

mass on performance from childhood to senior athletes in Olym-

pic weightlifting. PLoS One. 2020;15(9):e0238369.

3. Physical activity and exercise during pregnancy and the postpar-

tum period: ACOG Committee Opinion, Number 804. Obstet

Gynecol. 2020;135(4):e178–88.

4. Brown W, Hayman M, Haakstad L, Mielke G, Mena G, Lamerton

T, etal. Evidence-based physical activity guidelines for pregnant

women. Report for the Australian Government Department of

Health, March 2020. In: Health CAGDo, editor. 2021.

5. Mottola MF, Davenport MH, Ruchat SM, Davies GA, Poitras

VJ, Gray CE, etal. 2019 Canadian guideline for physical activity

throughout pregnancy. Br J Sports Med. 2018;52(21):1339–46.

6. UK Chief Medical Oﬃcers Physical Activity Guidelines: UK

Chief Medical Oﬃcers’ report 2019. Available from: https:// www.

gov. uk/ gover nment/ publi catio ns/ physi cal- activ ity- guide lines- uk-

chief- medic al- oﬃc ers- report.Accessed 1 August 2022

7. Cai C, Vandermeer B, Khurana R, Nerenberg K, Featherstone R,

Sebastianski M, etal. The impact of occupational activities dur-

ing pregnancy on pregnancy outcomes: a systematic review and

metaanalysis. Am J Obstet Gynecol. 2020;222(3):224–38.

8. Cai C, Davenport MH. Prenatal physical activity paradox: occu-

pational versus leisure-time physical activity. Br J Sports Med.

2022;56(7):365–6.

9. Wikander L, Kirshbaum MN, Waheed N, Gahreman DE. Urinary

incontinence in competitive women powerlifters: a cross-sectional

survey. Sports Med Open. 2021;7(1):89.

10. De Mattos Lourenco TR, Matsuoka PK, Baracat EC, Haddad JM.

Urinary incontinence in female athletes: a systematic review. Int

Urogynecol J. 2018;29(12):1757–63.

11. Yang J, Cheng JW, Wagner H, Lohman E, Yang SH, Krishingner

GA, etal. The eﬀect of high impact crossﬁt exercises on stress

urinary incontinence in physically active women. Neurourol Uro-

dyn. 2019;38(2):749–56.

12. Elks W, Jaramillo-Huﬀ A, Barnes KL, Petersen TR, Komesu YM.

The Stress Urinary Incontinence in CrossFit (SUCCeSS) Study.

Female Pelvic Med Reconstr Surg. 2020;26(2):101–6.

13. Sangsawang B, Sangsawang N. Stress urinary incontinence in

pregnant women: a review of prevalence, pathophysiology, and

treatment. Int Urogynecol J. 2013;24(6):901–12.

14. Meah VL, Strynadka MC, Steinback CD, Davenport MH. Cardiac

responses to prenatal resistance exercise with and without the

Valsalva maneuver. Med Sci Sports Exerc. 2021;53(6):1260–9.

15. Gould S, Cawyer C, Dell’Italia L, Harper L, McGwin G, Bamman

M. Resistance training does not decrease placental blood ﬂow

during Valsalva maneuver: a novel use of 3D Doppler power ﬂow

ultrasonography. Sports Health. 2021;13(5):476–81.

16. Green RC, Schneider K, Mac LA. The fetal heart response to

static antenatal exercises in the supine position. Aust J Physiother.

1988;34(1):3–7.

17. Calvin S, Jones OW 3rd, Knieriem K, Weinstein L. Oxygen

saturation in the supine hypotensive syndrome. Obstet Gynecol.

1988;71(6 Pt 1):872–7.

18. Kinsella SM, Lohmann G. Supine hypotensive syndrome. Obstet

Gynecol. 1994;83(5 Pt 1):774–88.

19. Ryo E, Okai T, Takagi K, Okuno S, Sadatsuki M, Kaneko M, etal.

Comparison of umbilical artery Doppler velocimetry between

maternal supine position and complete left lateral position in

predicting obstetric complications. Ultrasound Obstet Gynecol.

1998;11(6):415–8.

411International Urogynecology Journal (2023) 34:405–411

1 3

20. Massoth C, Chappell D, Kranke P, Wenk M. Supine hypotensive

syndrome of pregnancy: a review of current knowledge. Eur J

Anaesthesiol. 2022;39(3):236–43.

21. Mottola MF, Nagpal TS, Bgeginski R, Davenport MH, Poitras

VJ, Gray CE, etal. Is supine exercise associated with adverse

maternal and fetal outcomes? A systematic review. Br J Sports

Med. 2019;53(2):82–9.

22. Good Practice Statement. Supine lying during pregnancy. J Pelvic

Obstet Gynaecol Physiother. 2018;122:77–83.

23. Public Health Agency of Canada. Canadian Chronic Disease Indi-

cators. 2016.

24. McCurdy AP, Boule NG, Sivak A, Davenport MH. Effects

of exercise on mild-to-moderate depressive symptoms in

the postpartum period: a meta-analysis. Obstet Gynecol.

2017;129(6):1087–97.

25. Betran AP, Ye J, Moller AB, Souza JP, Zhang J. Trends and pro-

jections of caesarean section rates: global and regional estimates.

BMJ Glob Health. 2021;6(6):e005671.

26. Hackett DA, Chow CM. The Valsalva maneuver: its eﬀect on

intra-abdominal pressure and safety issues during resistance exer-

cise. J Strength Cond Res. 2013;27(8):2338–45.

27. Moore R. Olympic weightlifting during pregnancy. Disrupt

Physio. 2020. Accessed 5 May 2022. Available from: https://

www. disru ptphy sio. com/ post/ olymp ic- weigh tlift ing- during-

pregn ancy.

28. Moossdorﬀ-Steinhauser HFA, Berghmans BCM, Spaanderman

MEA, Bols EMJ. Prevalence, incidence and bothersomeness

of urinary incontinence between 6 weeks and 1 year post-par-

tum: a systematic review and meta-analysis. Int Urogynecol J.

2021;32(7):1675–93.

29. Forner LB, Beckman EM, Smith MD. Do women runners report

more pelvic ﬂoor symptoms than women in CrossFit®? A cross-

sectional survey. Int Urogynecol J. 2021;32(2):295–302.

30. Davenport MH, Nesdoly A, Ray L, Thornton JS, Khurana R,

McHugh TF. Pushing for change: a qualitative study of the

experiences of elite athletes during pregnancy. Br J Sports Med.

2022;56(8):452–7.

31. Morkved S, Bo K. Eﬀect of pelvic ﬂoor muscle training dur-

ing pregnancy and after childbirth on prevention and treatment

of urinary incontinence: a systematic review. Br J Sports Med.

2014;48(4):299–310.

Publisher’s note Springer Nature remains neutral with regard to

jurisdictional claims in published maps and institutional aﬃliations.

Springer Nature or its licensor (e.g. a society or other partner) holds

exclusive rights to this article under a publishing agreement with the

author(s) or other rightsholder(s); author self-archiving of the accepted

manuscript version of this article is solely governed by the terms of

such publishing agreement and applicable law.

Impact of heavy resistance training on pregnancy and postpartum health outcomes

Online Supplement

Christina PREVETT, PT

Institute of Clinical Excellence, Concord, NC, USA

Miranda L. KIMBER, MSc

Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport and Recreation, Women and Children’s Health

Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada.

Lori FORNER, PT

The University of Queensland, Brisbane, Australia.

Marlize de VIVO, PhD

Canterbury Christ Church University, Active Pregnancy Foundation, United Kingdom

Margie H. DAVENPORT, PhD

Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport and Recreation, Women and Children’s Health

Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada.

Corresponding Author

Margie H. Davenport, PhD

Program for Pregnancy and Postpartum Health

Faculty of Kinesiology, Sport, and Recreation

University of Alberta

1-059D Li Ka Shing Centre for Health Research Innovation

8602 - 112 St

Edmonton, Alberta, Canada

T6G 2E1

Tel: (780)492-0642

Email: margie.davenport@ualberta.ca

Table 1: Participant demographics. Data presented as mean ± SD or n (%).

Age at delivery (years) (n = 250)

29.8 ±3.9

Gestational age at delivery (n = 242)

38.6 ± 5.5

Pre-pregnancy weight (n = 594) (kg)

68.5 ± 14.8

Height (n = 574) (cm)

166.3 ± 7.3

Location (n = 676)

Australia

53

7.84%

Belgium

2

0.30%

Canada

128

18.93%

Czechia

1

0.15%

Finland

1

0.15%

Germany

3

0.44%

Iceland

2

0.30%

Ireland

19

2.81%

Israel

1

0.15%

Italy

1

0.15%

Mexico

2

0.30%

New Zealand

6

0.89%

Portugal

1

0.15%

Qatar

1

0.15%

South Africa

1

0.15%

Sweden

34

5.03%

Switzerland

3

0.44%

United Arab Emirates

4

0.59%

United Kingdom

91

13.46%

United States

322

47.63%

Sporting Career (n = 675)

Weightlifting

332

49%

Cross Fit

410

61%

Other

87

13%

Highest level of competition/training (n = 673)

Recreational athlete

594

88%

National level athlete

47

7%

International athlete

9

1%

World championship/Olympic games

6

1%

Other

17

3%

Pre-pregnancy 1RM

Squat (n = 455) (kg)

87.0 ± 25.6

Bench (n = 390) (kg)

55.1 ± 20.8

Deadlift (n = 452) (kg)

105.9 ±30.0

Clean (n = 360) (kg)

63.0 ± 18.9

Clean and jerk (n = 333) (kg)

60.9 ± 18.0

Snatch (n = 323) (kg)

47.3 ± 14.3

Pre-pregnancy Weightlifting Training Volume

Days per week (n = 490)

3.8 ± 1.17

Duration per session (n = 488) (min)

54.8 ± 21.1

RPE (n = 460) (1 = min; 10 = max)

7.0 ± 1.1

1%RM (n = 372)

76.2 ± 10.6

Pre-pregnancy Moderate Intensity Training Volume

Days per week (n = 417)

3.7 ± 1.62

Duration per session (n = 412)

40.3 ± 16.0

Pre-pregnancy Vigorous Intensity Training Volume

Days per week (n = 382)

3.0 ± 1.4

Duration per session (n = 374)

33.7 ± 16.6

Table 2. Reproductive Outcomes. Data presented as n (%).

Complications during pregnancy or delivery (n = 589)

Gestational diabetes

4

1%

Preeclampsia

17

3%

Gestational hypertension

18

3%

Premature labour

8

1%

Preterm delivery (< 37 weeks)

15

3%

Unexplained vaginal bleeding

10

2%

Placenta previa after 28 weeks

6

1%

Incompetent cervix

1

0%

Twin pregnancy

3

1%

Anemia

12

2%

Depression

7

1%

Anxiety

11

2%

Intrauterine growth restriction

10

2%

Cesarean section

77

13%

Instrumental delivery (forceps)

16

3%

Instrumental delivery (vacuum)

14

2%

Other

66

11%

No complications

388

66%

Did you experience urinary incontinence during

pregnancy? (n = 430)

Yes

159

37%

No

270

63%

Prefer not to say

1

0%

Did you experience prolapse during pregnancy?

(n = 429)

Yes

12

3%

No

416

97%

Prefer not to say

1

0%

Health complications following delivery (n = 574)

Depression

38

7%

Anxiety

43

7%

Diastasis recti

24

4%

Anal incontinence

5

1%

Pain with sex

32

6%

Breastfeeding complication

27

5%

Injury

16

3%

Other

51

9%

No complications

459

80%

Did you experience urinary incontinence

following delivery? (n = 426)

Yes

241

57%

No

182

43%

Prefer not to say

3

1%

Did you experience prolapse following delivery?

(n = 425)

Yes

60

14%

No

362

85%

Prefer not to say

3

1%

Table 3. Prenatal Olympic weightlifting participation vs no participation reproductive outcomes. Data presented as % (n). Total respondents 432

including 308 experiencing urinary incontinence during pregnancy and 124 not.

Complications during pregnancy

or delivery

Engaged in Olympic

weightlifting

Did not engage in

Olympic weightlifting

P value

OR [95% CI]

Yes

33%

(n=101/305)

38%

(n=46/121)

0.37

0.81 [0.52 – 1.25]

Gestational diabetes

0%

(n=1/305)

2%

(n=3/121)

0.07

0.13 [0.00 – 0.88]

Preeclampsia

3%

(n=9/305)

2%

(n=3/121)

>0.99

1.20 [0.32 – 4.16]

Gestational hypertension

3%

(n=8/305)

2%

(n=3/121)

>0.99

1.06 [0.32 – 3.75]

Premature labour

1%

(n=2/305)

2%

(n=3/121)

0.14

0.26 [0.05 – 1.29]

Preterm delivery (< 37

weeks)

3%

(n=9/305)

4%

(n=5/121)

0.55

0.71 [0.24 – 1.92]

Unexplained vaginal

bleeding

1%

(n=3/305)

1%

(n=3/121)

0.36

0.39 [0.09 – 1.70]

Placenta previa after 28

weeks

2%

(n=5/305)

0%

(n=0/121)

0.33

+infinity [0.59 – +infinity]

Incompetent cervix

0%

(n=1/305)

0%

(n=0/121)

>0.99

+infinity [0.04 - +infinity]

Twin pregnancy

1%

(n=2/305)

1%

(n=1/121)

>0.99

0.79 [0.09 – 11.57]

Triplet or higher order

multiple pregnancy

0%

(n=0/305)

0%

(n=0/121)

>0.99

-

Type 1 diabetes

0%

(n=0/305)

1%

(n=1/121)

0.28

0.00 [0.00 – 3.57]

Type 2 diabetes

0%

(n=1/305)

0%

(n=0/121)

>0.99

+infinity [0.04 - +infinity]

Thyroid disease

2%

(n=5/305)

0%

(n=0/121)

0.33

+infinity [0.59 – +infinity]

Anemia

3%

(n=9/305)

2%

(n=2/121)

0.74

1.81 [0.47 – 8.45]

Malnutrition

0%

(n=0/305)

0%

(n=0/121)

>0.99

-

Eating disorder

0%

(n=0/305)

0%

(n=0/121)

>0.99

-

Depression

0%

(n=1/305)

2%

(n=2/121)

0.20

0.20 [0.01 – 1.70]

Anxiety

2%

(n=5/305)

2%

(n=2/121)

>0.99

0.99 [0.21 – 5.04]

Nausea or vomiting

3%

(n=8/305)

7%

(n=9/121)

0.03

0.34 [0.13 – 0.83]

Intrauterine growth

restriction

1%

(n=3/305)

2%

(n=3/121)

0.36

0.39 [0.09 – 1.70]

Caesarean section

13%

(n=39/305)

17%

(n=20/121)

0.35

0.74 [0.41 – 1.33]

Instrumental delivery

(forceps)

3%

(n=8/305)

3%

(n=4/121)

0.75

0.79 [0.24 – 2.39]

Instrumental delivery

(vacuum)

3%

(n=8/305)

2%

(n=2/121)

0.73

1.60 [0.39 – 7.59]

Perineal tearing, 1st degree

3%

(n=9/305)

2%

(n=3/121)

>0.99

1.20 [0.32 – 4.16]

Perineal tearing, 2nd degree

8%

(n=23/305)

7%

(n=8/121)

0.84

1.15 [0.52 – 2.50]

Perineal tearing, 3rd degree

3%

(n=10/305)

4%

(n=5/121)

0.77

0.79 [0.29 – 2.10]

Perineal tearing, 4th degree

0%

(n=1/305)

0%

(n=0/121)

>0.99

+infinity [0.04 – +infinity]

Injury

1%

(n=4/305)

1%

(n=1/121)

>0.99

1.60 [0.26 – 19.66]

Other

10%

(n=31/305)

13%

(n=16/121)

0.39

0.74 [ 0.40 – 1.45]

Prefer not to say

0%

(n=0/305)

0%

(n=0/121)

>0.99

-

First stage of labour length

<8 hours

40%

(n=114/286)

49%

(n=54/110)

0.11

0.69 [0.44 – 1.06]

8 - 12 hours

20%

(n=58/286)

18%

(n=20/110)

0.67

1.15 [0.65 – 1.98]

12 - 18 hours

14%

(n=39/286)

11%

(n=12/110)

0.51

1.29 [0.67 – 2.47]

18 - 24 hours

13%

(n=36/286)

8%

(n=9/110)

0.29

1.62 [0.75 – 3.49]

> 24 hours

14%

(n=39/286)

14%

(n=15/110)

>0.99

1.00 [0.53 – 1.87]

Delivery Outcomes

Vaginal

60%

(n=172/286)

64%

(n=70/110)

0.57

0.86 [0.55 – 1.35]

Prolonged labour

5%

(n=12/286)

2%

(n=2/110)

0.37

2.37 [0.59 – 10.75]

Stalled labour

5%

(n=13/286)

4%

(n=4/110)

0.79

1.26 [0.42 – 3.61]

Fatigue

1%

(n=2/286)

0%

(n=0/110)

>0.99

+infinity [0.18 – +infinity]

Baby was breech

3%

(n=9/286)

6%

(n=7/110)

0.16

0.48 [0.19 – 1.25]

Fetal distress

10%

(n=28/286)

9%

(n=10/110)

>0.99

1.09 [0.52 – 2.22]

Other

10%

(n=29/286)

12%)

(n=13/110)

0.72

0.84 [0.42 – 1.75]

Health complications following

delivery

Yes

20%

(n=62/306)

21%

(n=25/120)

0.79

0.93 [0.54 – 1.59]

Depression

7%

(n=20/306)

8%

(n=9/120)

0.68

0.86 [0.39 – 2.01]

Anxiety

8%

(n=23/306)

11%

(n=13/120)

0.33

0.67 [0.33 – 1.35]

Diastisis recti

5%

(n=16/306)

3%

(n=4/120)

0.92

1.60 [0.57 – 4.49]

Urinary incontinence

6%

(n=18/306)

5%

(n=6/120)

0.82

1.19 [0.48 – 2.95]

Anal incontinence

1%

(n=2/306)

3%

(n=3/120)

0.14

0.26 [0.05 – 1.28]

Pain with sex

5%

(n=16/306)

8%

(n=9/120)

0.37

0.68 [0.31 – 1.66]

Breastfeeding complication

4%

(n=12/306)

7%

(n=8/120)

0.31

0.57 [0.24 – 1.39]

Injury

3%

(n=9/306)

2%

(n=2/120)

0.74

1.79 [0.46 – 8.35]

Other

10%

(n=30/306)

13%

(n=15/120)

0.48

0.76 [0.40 – 1.43]

Prefer not to say

0%

(n=0/306)

0%

(n=0/120)

>0.99

-

Table 4. Prenatal Valsalva maneuver participation vs no participation reproductive outcomes. Data presented as % (n). Total respondents 418

including 142 participating in Valsalva during pregnancy 276 not.

Complications during pregnancy

or delivery

Engaged in Valsalva

Did not engage in

Valsalva

P value OR [95% CI]

Yes

32%

(n=46/142)

36%

(n=96/270)

0.59

0.87 [0.57 – 1.33]

Gestational diabetes

0%

(n=0/142)

1%

(n=4/270)

0.30

0.00 [0.00 – 1.91]

Preeclampsia

3%

(n=4/142)

3%

(n=8/270)

0.99

0.95 [0.31 – 3.16]

Gestational hypertension

3%

(n=4/142)

3%

(n=7/270)

0.99

1.09 [0.35 – 3.47]

Premature labour

2%

(n=3/142)

1%

(n=2/270)

0.35

2.89 [0.58 – 16.41]

Preterm delivery (< 37

weeks)

4%

(n=5/142)

3%

(n=9/270)

0.99

1.06 [0.39 – 3.08]

Unexplained vaginal

bleeding

2%

(n=2/142)

1%

(n=3/270)

0.99

1.27 [0.22 – 6.28]

Placenta previa after 28

weeks

2%

(n=3/142)

1%

(n=2/270)

0.35

2.89 [0.58 – 16.41]

Incompetent cervix

1%

(n=1/142)

0%

(n=0/270)

0.34

+infinity[0.21 - +infinity]

Twin pregnancy

2%

(n=3/142)

0%

(n=0/270)

0.04

+infinity [1.66 - +infinity]

Triplet or higher order

multiple pregnancy

0%

(n=0/142)

0%

(n=0/270)

>0.99

-

Type 1 diabetes

0%

(n=0/142)

0%

(n=1/270)

>0.99

-

Type 2 diabetes

1%

(n=1/142)

0%

(n=0/270)

0.34

+infinity[0.21 - +infinity]

Thyroid disease

1%

(n=1/142)

1%

(n=3/270)

0.99

0.63 [0.05 – 4.27]

Anemia

2%

(n=3/142)

3%

(n=8/270)

0.76

0.71 [0.20 – 2.26]

Malnutrition

0%

(n=0/142)

0%

(n=0/270)

>0.99

-

Eating disorder

0%

(n=0/142)

0%

(n=0/270)

>0.99

-

Depression

0%

(n=0/142)

1%

(n=3/270)

0.55

0.00 [0.00 – 2.19]

Anxiety

3%

(n=4/142)

1%

(n=3/270)

0.24

2.58 [0.68 – 10.33]

Nausea or vomiting

5%

(n=7/142)

4%

(n=10/270)

0.61

1.35 [0.52 – 3.74]

Intrauterine growth

restriction

1%

(n=2/142)

1%

(n=4/270)

0.99

0.95 [0.18 – 4.12]

Caesarean section

11%

(n=16/142)

16%

(n=43/270)

0.24

0.67 [0.36 – 1.25]

Instrumental delivery

(forceps)

3%

(n=4/142)

3%

(n=8/270)

0.99

0.95 [0.31 – 3.16]

Instrumental delivery

(vacuum)

3%

(n=4/142)

2%

(n=5/270)

0.50

1.54 [0.46 – 5.18]

Perineal tearing, 1st degree

2%

(n=3/142)

3%

(n=9/270)

0.56

0.63 [0.18 – 2.31]

Perineal tearing, 2nd degree

8%

(n=11/142)

6%

(n=17/270)

0.68

1.25 [0.55 – 2.73]

Perineal tearing, 3rd degree

4%

(n=6/142)

3%

(n=9/270)

0.78

1.28 [0.45 – 3.46]

Perineal tearing, 4th degree

1%

(n=1/142)

0%

(n=0/270)

0.34

+infinity [0.21 - +infinity]

Injury

1%

(n=1/142)

1%

(n=4/270)

0.66

0.47 [0.04 – 2.88]

Other

10%

(n=14/142)

11%

(n=30/270)

0.74

0.88 [0.45 – 1.68]

Prefer not to say

0%

(n=0/142)

0%

(n=0/270)

>0.99

-

First stage of labour length

<8 hours

79%

(n=100/127)

80%

(n=204/256)

0.89

0.87 [0.57 – 1.35]

8 - 12 hours

21%

(n=27/127)

20%

(n=52/256)

0.89

1.06 [0.62 – 1.77]

12 - 18 hours

13%

(n=17/127)

13%

(n=34/256)

>0.99

1.01 [0.54 – 1.88]

18 - 24 hours

11%

(n=14/127)

11%

(n=29/256)

>0.99

0.97 [0.49 – 1.89]

> 24 hours

21%

(n=27/127)

20%

(n=52/256)

0.89

1.22 [0.67 – 2.19]

Delivery Outcomes

Vaginal

62%

(n=88/142)

58%

(n=148/256)

0.46

1.19 [0.77 – 1.81]

Prolonged labour

4%

(n=5/142)

4%

(n=10/256)

>0.99

0.90 [0.34 – 2.44]

Stalled labour

4%

(n=5/142)

5%

(n=12/256)

0.80

0.74 [0.28 – 2.10]

Fatigue

1%

(n=1/142)

0%

(n=1/256)

>0.99

1.81 [0.09 – 34.48]

Baby was breech

6%

(n=8/142)

4%

(n=9/256)

0.31

1.64 [0.63 – 4.02]

Fetal distress

8%

(n=12/142)

11%

(n=27/256)

0.60

0.78 [0.39 – 1.62]

Other

10%

(n=14/142)

11%)

(n=27/256)

0.87

0.93 [0.47 – 1.83]

Health complications following

delivery

Yes

25%

(n=35/142)

19%

(n=52/272)

0.20

1.38 [0.86 – 2.25]

Depression

7%

(n=10/142)

6%

(n=17/272)

0.83

1.14 [0.52 – 2.56]

Anxiety

11%

(n=15/142)

7%

(n=19/272)

0.26

1.57 [0.78 – 3.23]

Diastisis recti

4%

(n=6/142)

5%

(n=13/272)

>0.99

0.88 [0.34 – 2.21]

Urinary incontinence

8%

(n=12/142)

4%

(n=12/272)

0.12

2.00 [0.85 – 4.69]

Anal incontinence

2%

1%

0.34

2.91 [0.59 – 16.53]

(n=3/142)

(n=2/272)

Pain with sex

8%

(n=11/142)

5%

(n=14/272)

0.29

1.55 [0.71 – 3.39]

Breastfeeding complication

4%

(n=8/142)

5%

(n=14/272)

0.82

1.10 [0.47 – 2.67]

Injury

3%

(n=4/142)

2%

(n=6/272)

0.99

1.29 [0.40 – 4.85]

Other

11%

(n=15/142)

10%

(n=28/272)

0.74

1.03 [0.55 – 1.97]

Prefer not to say

0%

(n=0/142)

0%

(n=0/272)

>0.99

-

Table 5. Prenatal supine weightlifting participation vs no participation reproductive outcomes. Data presented as % (n). Total respondents 448

including 307 participating in supine weightlifting during pregnancy 141 not.

Complications during pregnancy

or delivery

Engaged in supine

weightlifting

Did not engage in

supine weightlifting

P value

OR [95% CI]

Yes

36%

(n=109/302)

32%

(n=45/140)

0.45

1.19 [0.78 – 1.81]

Gestational diabetes

1%

(n=3/302)

1%

(n=2/140)

0.65

0.69 [0.14 – 3.94]

Preeclampsia

3%

(n=10/302)

1%

(n=2/140)

0.35

2.36 [0.54 – 10.90]

Gestational hypertension

3%

(n=8/302)

3%

(n=4/140)

>0.99

0.93 [0.28 – 2.81]

Premature labour

1%

(n=4/302)

1%

(n=1/140)

>0.99

1.87 [0.31 – 22.98]

Preterm delivery (< 37

weeks)

3%

(n=9/302)

4%

(n=5/140)

0.77

0.83 [0.29 – 2.25]

Unexplained vaginal

bleeding

2%

(n=6/302)

0%

(n=0/140)

0.18

+infinity [0.66 - +infinity]

Placenta previa after 28

weeks

2%

(n=5/302)

0%

(n=0/140)

0.18

+infinity [0.69 - +infinity]

Incompetent cervix

0%

(n=1/302)

0%

(n=0/140)

>0.99

+infinity [0.05 - +infinity]

Twin pregnancy

1%

(n=3/302)

0%

(n=0/140)

0.55

+infinity [0.40 - +infinity]

Triplet or higher order

multiple pregnancy

0%

(n=0/302)

0%

(n=0/140)

>0.99

-

Type 1 diabetes

0%

(n=0/302)

1%

(n=1/140)

0.32

0.00 [0.00 – 4.17]

Type 2 diabetes

0%

(n=0/302)

1%

(n=1/140)

0.32

0.00 [0.00 – 4.17]

Thyroid disease

1%

(n=2/302)

2%

(n=3/140)

0.33

0.30 [0.05 – 1.51]

Anemia

3%

(n=8/302)

2%

(n=3/140)

>0.99

1.24 [0.38 – 4.39]

Malnutrition

0%

(n=0/302)

0%

(n=0/140)

>0.99

-

Eating disorder

0%

(n=0/302)

0%

(n=0/140)

>0.99

-

Depression

0%

(n=1/302)

1%

(n=2/140)

0.24

0.23 [0.02 – 2.00]

Anxiety

2%

(n=7/302)

1%

(n=2/140)

0.73

1.64 [0.36 – 7.98]

Nausea or vomiting

4%

(n=12/302)

4%

(n=5/140)

>0.99

1.12 [0.40 – 2.92]

Intrauterine growth

restriction

1%

(n=4/302)

1%

(n=2/140)

>0.99

0.93 [0.21 – 4.92]

Caesarean section

15%

(n=46/302)

14%

(n=19/140)

0.77

1.14 [0.65 – 2.04]

Instrumental delivery

(forceps)

2%

(n=6/302)

4%

(n=6/140)

0.21

0.45 [0.14 – 1.46]

Instrumental delivery

(vacuum)

3%

(n=8/302)

2%

(n=3/140)

>0.99

1.24 [0.38 – 4.39]

Perineal tearing, 1st degree

3%

(n=10/302)

1%

(n=2/140)

0.35

2.36 [0.54 – 10.90]

Perineal tearing, 2nd degree

8%

(n=23/302)

7%

(n=10/140)

>0.99

1.07 [0.50 – 2.21]

Perineal tearing, 3rd degree

4%

(n=12/302)

2%

(n=3/140)

0.41

1.89 [0.60 – 6.36]

Perineal tearing, 4th degree

0%

(n=1/302)

0%

(n=0/140)

>0.99

+infinity [0.05 - +infinity]

Injury

1%

(n=1/302)

1%

(n=2/140)

0.24

0.23 [0.02 – 1.99]

Other

11%

(n=34/302)

12%

(n=17/140)

0.87

0.92 [0.50 – 1.69]

Prefer not to say

0%

(n=0/302)

0%

(n=0/140)

>0.99

-

First stage of labour length

<8 hours

78%

(n=215/274)

83%

(n=110/133)

0.36

0.72 [0.48 – 1.09]

8 - 12 hours

22%

(n=59/274)

18%

(n=23/133)

0.36

1.31 [0.78 – 2.23]

12 - 18 hours

13%

(n=36/274)

12%

(n=16/133)

0.87

1.11 [0.59 – 2.10]

18 - 24 hours

11%

(n=29/274)

13%

(n=17/133)

0.51

0.81 [0.44 – 1.53]

> 24 hours

22%

(n=59/274)

18%

(n=23/133)

0.36

1.54 [0.82 – 2.87]

Delivery Outcomes

Vaginal

70%

(n=167/238)

71%

(n=80/112)

0.90

0.94 [0.57 – 1.54]

Prolonged labour

4%

(n=10/238)

5%

(n=6/112)

0.60

0.77 [0.29 – 2.17]

Stalled labour

5%

(n=13/238)

4%

(n=4/112)

0.60

1.56 [0.51 – 4.47]

Fatigue

0%

(n=1/238)

1%

(n=1/112)

0.60

0.47 [0.02 – 8.97]

Baby was breech

5%

(n=13/238)

4%

(n=4/112)

0.31

1.56 [0.51 – 4.47]

Fetal distress

11%

(n=27/238)

13%

(n=14/112)

0.73

0.90 [0.45 – 1.80]

Other

14%

(n=33/238)

13%

(n=14/112)

0.87

1.13 [0.59 – 2.19]

Health complications following

delivery

Yes

21%

(n=64/301)

23%

(n=32/141)

0.80

0.92 [0.58 – 1.48]

Depression

6%

(n=19/301)

9%

(n=12/141)

0.43

0.72 [0.36 – 1.52]

Anxiety

9%

(n=15/301)

9%

(n=12/141)

0.20

0.57 [0.25 – 1.25]

Diastasis recti

4%

(n=12/301)

6%

(n=9/141)

0.34

0.61 [0.26 – 1.49]

Urinary incontinence

6%

(n=17/301)

6%

(n=8/141)

>0.99

1.00 [0.43 – 2.24]

Anal incontinence

1%

2%

0.39

0.46 [0.11 – 2.01]

(n=3/301)

(n=3/141)

Pain with sex

5%

(n=16/301)

8%

(n=11/141)

0.39

0.66 [0.30 – 1.47]

Breastfeeding complication

5%

(n=14/301)

8%

(n=11/141)

0.19

0.58 [0.26 – 1.27]

Injury

3%

(n=8/301)

3%

(n=4/141)

>0.99

0.94 [0.28 – 2.84]

Other

11%

(n=34/301)

11%

(n=16/141)

>0.99

0.99 [0.53 – 1.90]

Prefer not to say

0%

(n=0/301)

0%

(n=0/141)

>0.99

-

Table 6. Maintenance of pre-pregnancy resistance training level until delivery vs reduction in training level prior-to delivery reproductive

outcomes. Data presented as % (n). Total respondents 440 including 104 respondents who maintained pre-pregnancy training level until delivery

and 336 respondents who reduced training levels prior-to delivery.

Complications during pregnancy

or delivery

Pre-pregnancy

training level

maintained until

delivery

Reduced pre-pregnancy

training level before

delivery

P value OR [95% CI]

Yes

23%

(n=24/104)

38%

(n=127/336)

0.006

0.49 [0.29 – 0.81]

Gestational diabetes

2%

(n=2/104)

1%

(n=2/336)

0.24

3.28 [0.51 – 21.04]

Preeclampsia

1%

(n=1/104)

3%

(n=11/336)

0.31

0.29 [0.03 – 1.63]

Gestational hypertension

0%

(n=0/104)

4%

(n=12/336)

0.08

0.00 [0.00 – 1.03]

Premature labour

0%

(n=0/104)

1%

(n=5/336)

0.60

0.00 [0.00 – 2.18]

Preterm delivery (< 37

weeks) 3%

(n=2/104)

4%

(n=12/336)

0.55

0.53 [0.12 – 2.13]

Unexplained vaginal

bleeding 0%

(n=0/104)

2%

(n=7/336)

0.21

0.00 [0.00 – 1.77]

Placenta previa after 28

weeks 0%

(n=0/104)

1%

(n=5/336)

0.60

0.00 [0.00 – 2.18]

Incompetent cervix

0%

(n=0/104)

0%

(n=1/336)

>0.99

0.00 [0.00 – 29.08]

Twin pregnancy

0%

(n=0/104)

1%

(n=3/336)

>0.99

0.00 [0.00 – 3.73]

Triplet or higher order

multiple pregnancy 0%

(n=0/104)

0%

(n=0/336)

>0.99

-

Type 1 diabetes

0%

(n=0/104)

0%

(n=1/336)

>0.99

0.00 [0.00 – 29.08]

Type 2 diabetes

0%

(n=1/104)

0%

(n=1/336)

0.42

3.25 [0.17 – 61.94]

Thyroid disease

1%

(n=1/104)

1%

(n=4/336)

>0.99

0.81 [0.07 – 4.93]

Anemia

3%

(n=3/104)

2%

(n=8/336)

0.73

1.22 [0.34 – 4.04]

Malnutrition

0%

(n=0/104)

0%

(n=0/336)

>0.99

-

Eating disorder

0%

(n=0/104)

0%

(n=0/336)

>0.99

-

Depression

0%

(n=0/104)

1%

(n=3/336)

>0.99

0.00 [0.00 – 3.73]

Anxiety

1%

(n=1/104)

2%

(n=7/336)

0.69

0.46 [0.04 – 2.82]

Nausea or vomiting

2%

(n=2/104)

5%

(n=16/336)

0.27

0.39 [0.09 – 1.63]

Intrauterine growth

restriction 0%

(n=0/104)

2%

(n=6/336)

0.34

0.00 [0.00 – 2.28]

Caesarean section

13%

(n=14/104)

15%

(n=49/336)

0.87

0.91 [0.49 – 1.69]

Instrumental delivery

(forceps) 2%

(n=2/104)

3%

(n=10/336)

0.74

0.64 [0.14 – 2.81]

Instrumental delivery

(vacuum) 2%

(n=2/104)

3%

(n=9/336)

>0.99

0.71 [0.15 – 2.77]

Perineal tearing, 1st degree

1%

(n=1/104)

3%

(n=11/336)

0.31

0.29 [0.03 – 1.63

Perineal tearing, 2nd degree

4%

(n=4/104)

8%

(n=26/336)

0.26

0.48 [0.18 – 1.29]

Perineal tearing, 3rd degree

1%

(n=1/104)

4%

(n=14/336)

0.21

0.22 [0.02 – 1.37]

Perineal tearing, 4th degree

0%

(n=0/104)

0%

(n=1/336)

>0.99

0.00 [0.00 – 29.08]

Injury

0%

(n=0/104)

1%

(n=5/336)

0.60

0.00 [0.00 – 2.18]

Other

9%

(n=9/104)

11%

(n=38/336)

0.59

0.74 [ 0.35 – 1.59]

Prefer not to say

0%

(n=0/104)

0%

(n=0/336)

>0.99

-

First stage of labour length

<8 hours

45%

(n=47/104)

40%

(n=121/305)

0.36

1.25 [0.80 – 1.96]

8 - 12 hours

20%

(n=21/104)

20%

(n=62/305)

>0.99

0.99 [0.57 – 1.73]

12 - 18 hours

11%

(n=11/104)

13%

(n=41/305)

0.50

0.76 [0.37 – 1.50]

18 - 24 hours

5%

(n=5/104)

13%

(n=39/305)

0.03

0.34 [0.14 – 0.90]

> 24 hours

13%

(n=13/104)

14%

(n=42/305)

0.87

0.89 [0.45 – 1.74]

Delivery Outcomes

Vaginal

57%

(n=59/104)

62%

(n=188/305)

0.42

0.82 [0.52 – 1.29]

Prolonged labour

1%

(n=1/104)

5%

(n=15/305)

0.08

0.19 [0.02 – 1.13]

Stalled labour

6%

(n=6/104)

4%

(n=11/305)

0.39

1.64 [0.60 – 4.54]

Fatigue

1%

(n=1/104)

0%

(n=1/305)

0.44

2.95 [0.15 – 56.23]

Baby was breech

6%

(n=6/104)

4%

(n=11/305)

0.39

1.64 [0.60 – 4.54]

Fetal distress

12%

(n=12/104)

10%

(n=29/305)

0.57

1.24 [0.62 – 2.55]

Other

10%

(n=10/104)

11%)

(n=35/305)

0.72

0.82 [0.40 – 1.72]

Health complications following

delivery

Yes

15%

(n=16/104)

23%

(n=75/331)

0.13

0.62 [0.35 – 1.10]

Depression

5%

(n=5/104)

8%

(n=25/331)

0.39

0.62 [0.25 – 1.64]

Anxiety

6%

(n=6/104)

9%

(n=31/331)

0.66

0.73 [0.31 – 1.79]

Diastisis recti

4%

(n=4/104)

5%

(n=16/331)

0.79

0.79 [0.28 – 2.20]

Urinary incontinence

3%

(n=3/104)

6%

(n=21/331)

0.22

0.44 [0.14 – 1.46]

Anal incontinence

0%

(n=0/104)

2%

(n=5/331)

0.60

0.00 [0.00 – 2.14]

Pain with sex

2%

(n=2/104)

7%

(n=23/331)

0.06

0.26 [0.06 – 0.99]

Breastfeeding complication

5%

(n=5/104)

5%

(n=16/331)

>0.99

0.99 [0.39 – 2.78]

Injury

3%

(n=3/104)

3%

(n=9/331)

>0.99

1.06 [0.30 – 3.95]

Other

11%

(n=11/104)

11%

(n=38/331)

0.86

0.91 [0.44 – 1.82]

Prefer not to say

0%

(n=0/104)

0%

(n=0/331)

>0.99

-

Table 7. Pregnancy Training Outcomes. Data presented as mean ± SD or n (%).

How far into your pregnancy were you able to keep

up your pre-pregnancy training level? (n = 445)

Until Delivery

108

24%

Until (Gestational Age)

21.2 ± 10.1

After you reduced your training schedule, did you

continue to train? (n = 328)

Yes

278

85%

No

50

15%

Weightlifting Done During Pregnancy

Olympic lifting

Engaged in during pregnancy (n = 432)

311

72%

Engaged until ___ weeks of gestation (n = 309)

29.81

8.65

Valsalva

Engaged in during pregnancy (n = 420)

141

34%

Engaged until ___ weeks of gestation (n = 140)

29.69

10.04

Lifting in supine position

Engaged in during pregnancy (n = 437)

306

71%

Engaged until ___ weeks of gestation (n = 307)

27.69

9.29

Weightlifting belt

Engaged in during pregnancy (n = 434)

45

10%

Engaged until ___ weeks of gestation (n = 45)

18.04

9.28

Pregnancy Weightlifting Training Volume

Days per week (n = 262)

2.94 ± 1.19

Duration per session (n = 254) (min)

44.09 ± 18.27

RPE (n = 237) (1 = min; 10 = max)

5.46 ± 1.23

1%RM (n = 200)

59.65 ± 14.72

Pregnancy Moderate Aerobic Training Volume

Days per week (n = 259)

3.72 ± 1.55

Duration per session (n = 253) (min)

36.05 ± 14.91

Pregnancy Vigorous Aerobic Training Volume

Days per week (n = 162)

2.20 ± 1.34

Duration per session (n = 159) (min)

25.97 ± 15.25

Table 8. Prenatal urinary incontinence vs continence pre-pregnancy training outcomes. Data presented as mean ± SD or n (%). Total respondents

429 including 159 experiencing urinary incontinence during pregnancy and 270 not.

Pre-pregnancy 1RM (kg)

Prenatal urinary

incontinence

Prenatal continence

P value

Squat

81.84 ± 26.46

(n = 144)

88.62 ± 25.89

(n = 254)

0.01

Bench

49.64 ± 14.93

(n = 126)

53.91 ± 17.54

(n = 228)

0.02

Deadlift

101.50 ± 30.88

(n = 145)

107.31 ± 30.22

(n = 251)

0.07

Clean

58.96 ± 19.22

(n = 119)

64.26 ± 19.25

(n = 198)

0.02

Clean and Jerk

55.80 ± 19.50

(n = 113)

62.65 ± 17.62

(n = 180)

0.002

Snatch

44.85 ± 15.14

(n = 107)

48.14 ± 14.59

(n = 175)

0.07

Pre-pregnancy Weightlifting Training

Volume

Days per week

3.70 ± 1.17

(n = 158)

3.87 ± 1.12

(n = 269)

0.14

Duration per session

54.43 ± 20.82

(n = 157)

55.93 ± 21.60

(n = 269)

0.48

RPE

7.02 ± 1.10

(n = 152)

6.99 ± 1.06

(n = 251)

0.77

%1RM

75.45 ± 11.87

(n = 122)

76.71 ± 10.03

(n = 208)

0.31

Pre-pregnancy Moderate Intensity

Aerobic Training

Days per week

3.66 ± 1.67

(n = 133)

3.65 ± 1.61

(n = 231)

0.93

Duration per session

40.30 ± 17.05

(n = 132)

41.50 ± 17.15

(n = 229)

0.52

Pre-pregnancy Vigorous Intensity

Aerobic Training

Days per week

3.07 ± 1.47

(n = 126)

3.03 ± 1.45

(n = 211)

0.79

Duration per session

35.04 ± 17.65

(n = 121)

34.07 ± 18.16

(n = 209)

0.64

Table 9. Prenatal urinary incontinence vs continence pregnancy training outcomes. Data presented as mean ± SD or n (%). Total respondents 429

including 159 experiencing urinary incontinence during pregnancy and 270 not.

How far into your pregnancy were you

able to keep up your pre-pregnancy

training level?

Prenatal urinary

incontinence

Prenatal continence

P value

OR [95% CI]

Until Delivery

26%

(n=40/155)

24%

(n=63/267)

0.64

1.13 [0.72 – 1.77]

Until (Gestational Age)

21.8 ± 9.6

(n = 115)

20.80 ± 10.39

(n = 204)

0.38

-

After you reduced your training

schedule, did you continue to train?

Yes

86%

(n=98/113)

84%

(n=167/199)

0.62

1.25 [0.66 – 2.36]

Olympic lifting

Engaged in during pregnancy

71%

(n=109/154)

74%

(n=190/257)

0.49

0.85 [0.55 – 1.34]

Engaged until ___ weeks of gestation

31.12 ± 7.66

29.17 ± 8.85

0.06

-

Valsalva

Engaged in during pregnancy

35%

(n=52/147)

33%

(n=84/255)

0.66

1.11 [0.72 – 1.70]

Engaged until ___ weeks of gestation

30.17 ± 9.85

29.32 ± 10.08

0.63

-

Lifting in a supine position

Engaged in during pregnancy

72%

(n=113/156)

70%

(n=180/259)

0.58

1.15 [0.74 – 1.80]

Engaged until ___ weeks of gestation

26.61 ± 9.41

28.75 ± 8.92

0.05

-

Weightlifting belt

Engaged in during pregnancy

14%

(n=21/153)

8%

(n=22/259)

0.10

1.71 [0.89 – 3.26]

Engaged until ___ weeks of gestation

15.48 ± 9.52

20.32 ± 8.69

0.09

-

Weightlifting Done During Pregnancy

Days per week

2.93 ± 1.19

(n = 92)

2.95 ± 1.16

(n = 159)

0.87

-

Duration per session

44.40 ± 17.65

(n = 91)

43.60 ± 18.17

(n = 153)

0.74

-

RPE

5.41 ± 1.30

(n = 84)

5.49 ± 1.22

(n = 145)

0.62

-

1%RM

59.06 ± 16.90

(n = 69)

60.12 ± 13.54

(n = 123)

0.63

-

Pregnancy Moderate Intensity Aerobic

Training

Days per week

3.82 ± 1.64

(n = 91)

3.70 ± 1.52

(n = 158)

0.54

-

Duration per session

36.24 ± 15.16

(n = 89)

36.01 ± 14.62

(n = 154)

0.91

-

Pregnancy Vigorous Intensity Aerobic

Training

Days per week

2.47 ± 1.50

(n = 57)

2.07 ± 1.24

(n = 100)

0.07

-

Duration per session

27.77 ± 16.12

(n = 56)

24.85 ± 14.63

(n = 98)

0.25

-

Table 10. Prenatal Olympic weightlifting participation vs no participation pre-pregnancy training outcomes. Data presented as mean ± SD or n

(%). Total respondents 426 including 302 engaging in Olympic weightlifting during pregnancy and 124 not.

Pre-pregnancy 1RM (kg)

Engaged in Olympic

weightlifting

Did not engage in Olympic

weightlifting

P value

Squat

90.60 ± 23.01

(n = 293)

75.09 ± 29.13

(n = 108)

<0.0001

Bench

55.35 ± 15.98

(n = 259)

48.11 ± 24.49

(n = 90)

0.002

Deadlift

111.18 ± 25.20

(n = 291)

88.71 ± 35.90

(n = 108)

<0.0001

Clean

65.69 ± 17.20

(n = 277)

43.21 ± 20.13

(n = 44)

<0.0001

Clean and Jerk

62.41 ± 17.29

(n = 265)

42.80 ± 19.01

(n = 33)

<0.0001

Snatch

48.24 ± 14.08

(n = 261)

34.69 ± 16.42

(n = 26)

<0.0001

Pre-pregnancy Weightlifting Training Volume

Days per week

3.96 ± 1.10

(n = 307)

3.38 ± 1.14

(n = 123)

<0.0001

Duration per session

53.62 ± 20.95

(n = 305)

58.07 ± 20.65

(n = 122)

0.05

RPE

7.04 ± 1.0

(n = 294)

6.91 ± 1.19

(n = 114)

0.27

%1RM

76.33 ± 10.34

(n = 260)

75.33 ± 11.87

(n = 76)

0.48

Pre-pregnancy Moderate Intensity Aerobic

Training

Days per week

3.68 ± 1.61

(n = 259)

3.59 ± 1.70

(n = 111)

0.67

Duration per session

39.13 ± 15.06

(n = 258)

42.59 ± 16.99

(n = 108)

0.05

Pre-pregnancy Vigorous Intensity Aerobic

Training

Days per week

3.15 ± 1.45

(n = 250)

2.71 ± 1.44

(n = 94)

0.01

Duration per session

32.30 ± 16.75

(n = 244)

38.42 ± 16.07

(n = 92)

0.003

Table 11. Prenatal Olympic weightlifting vs no participation pregnancy training outcomes. Data presented as mean ± SD or n (%). Total

respondents 426 including 302 engaging in Olympic weightlifting during pregnancy and 124 not.

How far into your pregnancy were you able to

keep up your pre-pregnancy training level?

Engaged in Olympic

weightlifting

Did not engage in

Olympic weightlifting

P value

OR [95%CI]

Until Delivery

25%

(n=74/301)

24%

(n=25/122)

0.45

1.27 [0.76 to 2.14]

Until (Gestational Age)

21.77 ± 9.86

(n = 227)

19.52 ± 10.53

(n = 97)

0.07

-

Olympic lifting

Engaged in during pregnancy

100%

(n=305/305)

0%

(n=0/124)

<0.0001

-

Engaged until ___ weeks of gestation

30.29 ± 8.01

-

Valsalva

Engaged in during pregnancy

38%

(n=110/293)

22%

(n=27/122)

0.003

2.12 [1.29 to 3.39]

Engaged until ___ weeks of gestation

30.19 ± 9.80

26.59 ± 11.09

0.10

-

Lifting in a supine position

Engaged in during pregnancy

52%

(n=160/306)

58%

(n=71/123)

0.34

0.80 [0.52 to 1.21]

Engaged until ___ weeks of gestation

27.90 ± 9.20

27.08 ± 9.75

0.52

-

Weightlifting belt

Engaged in during pregnancy

11%

(n=34/304)

7%

(n=8/118)

0.21

1.73 [0.80 to 3.69]

Engaged until ___ weeks of gestation

18.50 ± 9.57

12.13 ± 4.42

0.08

-

Weightlifting Done During Pregnancy

Days per week

3.09 ± 1.20

(n = 179)

2.55 ± 0.97

(n = 74)

0.0007

-

Duration per session

42.60 ± 18.97

46.94 ± 15.40

0.09

-

(n =173)

(n = 72)

RPE

5.46 ± 1.17

(n = 172)

5.50 ± 1.38

(n = 104)

0.82

1%RM

60.29 ± 13.96

(n = 154)

56.74 ± 17.00

(n = 43)

0.16

-

Pregnancy Moderate Intensity Aerobic

Training

Days per week

3.71 ± 1.42

(n = 178)

3.73 ± 1.86

(n =75)

0.93

-

Duration per session

35.00 ± 14.15

(n = 176)

38.17 ± 16.35

(n = 71)

0.13

-

Pregnancy Vigorous Intensity Aerobic

Training

Days per week

2.31 ± 1.33

(n = 123)

1.94 ± 1.39

(n = 34)

0.16

-

Duration per session

24.38 ± 14.60

(n = 121)

30.91 ± 16.56

(n = 33)

0.03

-

Table 12. Prenatal Valsalva maneuver participation vs no participation pre-pregnancy training outcomes. Data presented as mean ± SD or % (n).

Total respondents 418 including 142 participating in Valsalva during pregnancy and 276 not.

Pre-pregnancy 1RM (kg)

Engaged in Valsalva

Did not engage in Valsalva

P value

Squat

94.94 ± 23.88

(n = 138)

82.34 ± 24.93

(n = 250)

<0.0001

Bench

56.40 ± 14.80

(n = 125)

51.82 ± 20.34

(n = 217)

0.01

Deadlift

115.67 ± 28.84

(n = 138)

99.66 ± 29.54

(n = 250)

<0.0001

Clean

65.30 ± 17.30

(n = 114)

61.12 ± 20.21

(n = 192)

0.06

Clean and Jerk

61.95 ± 17.43

(n = 107)

59.17 ± 19.54

(n = 177)

0.20

Snatch

49.26 ± 13.79

(n = 104)

45.85 ± 15.51

(n = 168)

0.06

Pre-pregnancy Weightlifting Training

Volume

Days per week

4.07 ± 1.08

(n = 142)

3.62 ± 1.13

(n = 275)

<0.0001

Duration per session

60.78 ± 23.13

(n = 141)

52.29 ± 18.74

(n = 273)

0.002

RPE

7.13 ± 1.00

(n = 135)

6.96 ± 1.08

(n = 259)

0.12

%1RM

77.92 ± 10.07

(n = 120)

75.32 ± 10.90

(n = 206)

0.03

Pre-pregnancy Moderate Intensity

Aerobic Training

Days per week

3.57 ± 1.71

(n = 112)

3.62 ± 1.58

(n = 245)

0.80

Duration per session

39.32 ± 15.07

(n = 111)

40.97 ± 16.11

(n = 243)

0.35

Pre-pregnancy Vigorous Intensity

Aerobic Training

Days per week

2.97 ± 1.57

(n = 102)

3.03 ± 1.38

(n = 228)

0.76

Duration per session

30.80 ± 14.87

(n = 100)

35.36 ± 17.41

(n = 222)

0.02

Table 13. Prenatal Valsalva maneuver vs no participation pregnancy training outcomes. Data presented as mean ± SD or % (n). Total respondents

418 including 142 participating in Valsalva during pregnancy and 276 not.

How far into your pregnancy were

you able to keep up your pre-

pregnancy training level?

Engaged in Valsalva

Did not engage in

Valsalva

P value

OR [95% CI]

Until Delivery

26%

(n=36/140)

25%

(n=67/273)

0.81

1.06 [0.66 – 1.71]

Until (Gestational Age)

22.0 ± 9.9

(n = 104)

20.42 ± 10.08

(n = 206)

0.18

-

After you reduced your training

schedule, did you continue to train?

Yes

91%

(n=94/103)

82%

(n=165/201)

0.04

2.28 [1.10 – 4.98]

Olympic lifting

Engaged in during pregnancy

79%

(n=110/138)

67%

(n=183/275)

0.006

1.98 [1.21 – 3.26]

Engaged until ___ weeks of gestation

31.56 ± 7.29

29.19 ± 9.04

0.01

-

Lifting in a supine position

Engaged in during pregnancy

83%

(n=119/143)

63%

(n=170/273)

<0.0001

3.00 [1.80 – 5.02]

Engaged until ___ weeks of gestation

29.32 ± 9.17

26.65 ± 9.21

0.02

-

Weightlifting belt

Engaged in during pregnancy

19%

(n=27/141)

6%

(n=15/271)

<0.0001

4.04 [2.08 – 7.67]

Engaged until ___ weeks of gestation

18.30 ± 8.55

16.13 ± 10.78

0.51

-

Weightlifting Done During

Pregnancy

Days per week

3.10 ± 1.10

(n = 90)

2.85 ± 1.20

(n = 155)

0.16

-

Duration per session

47.44 ± 20.09

(n = 88)

41.98 ± 16.87

(n = 149)

0.03

-

RPE

5.71 ± 1.10

(n = 88)

5.36 ± 1.26

(n = 137)

0.03

-

1%RM

62.38 ± 13.31

(n = 80)

58.24 ± 15.43

(n = 111)

0.05

-

Pregnancy Moderate Intensity

Aerobic Training

Days per week

3.76 ± 1.55

(n = 89)

3.67 ± 1.56

(n = 156)

0.66

-

Duration per session

36.12 ± 14.77

(n = 89)

36.03 ± 15.25

(n = 150)

0.96

-

Pregnancy Vigorous Intensity

Aerobic Training

Days per week

2.38 ± 1.48

(n = 55)

2.10 ± 1.25

(n = 99)

0.24

-

Duration per session

24.55 ± 14.54

(n = 55)

26.61 ± 15.65

(n = 96)

0.41

-

Table 14. Prenatal supine weightlifting participation vs no participation pre-pregnancy training outcomes. Data presented as mean ± SD or % (n).

Total respondents 448 including 307 participating in supine weightlifting during pregnancy 141 not.

Pre-pregnancy 1RM (kg)

Engaged in supine

weightlifting

Did not engage in supine

weightlifting

P value

Squat

89.35 ± 25.19

(n = 286)

80.04 ± 24.76

(n = 130)

0.0005

Bench

55.34 ± 18.40

(n = 264)

47.60 ± 17.87

(n = 102)

0.0003

Deadlift

108.54 ± 30.25

(n = 284)

97.57 ± 28.43

(n = 130)

0.0004

Clean

63.92 ± 19.31

(n = 233)

59.12 ± 18.47

(n = 100)

0.03

Clean and Jerk

61.31 ± 18.10

(n = 216)

56.55 ± 19.13

(n = 90)

0.04

Snatch

47.92 ± 13.98

(n = 217)

44.54 ± 16.06

(n = 81)

0.10

Pre-pregnancy Weightlifting Training

Volume

Days per week

3.90 ± 1.09

(n = 307)

3.58 ± 1.19

(n = 140)

0.007

Duration per session

56.29 ± 21.28

(n = 306)

52.46 ± 18.62

(n = 138)

0.06

RPE

7.06 ± 1.07

(n = 291)

6.88 ± 1.05

(n = 133)

0.10

%1RM

76.41 ± 10.19

(n = 245)

75.19 ± 11.32

(n = 104)

0.35

Pre-pregnancy Moderate Intensity

Aerobic Training

Days per week

3.56 ± 1.56

(n = 262)

3.80 ± 1.78

(n = 118)

0.22

Duration per session

39.29 ± 15.96

(n = 260)

43.42 ± 16.37

(n = 117)

0.02

Pre-pregnancy Vigorous Intensity

Aerobic Training

Days per week

2.98 ± 1.42

(n = 244)

3.12 ± 1.51

(n = 109)

0.43

Duration per session

32.82 ± 15.63

(n = 238)

36.96 ± 18.57

(n = 107)

0.04

Table 15. Prenatal supine weightlifting participation vs no participation pregnancy training outcomes. Data presented as mean ± SD or % (n).

Total respondents 448 including 307 participating in supine weightlifting during pregnancy 141 not.

How far into your pregnancy were

you able to keep up your pre-

pregnancy training level?

Engaged in supine

weightlifting

Did not engage in

supine weightlifting

P value

OR [95% CI]

Until Delivery

25%

(n=73/301)

24%

(n=33/139)

0.25

0.74 [0.46 – 1.20]

Until (Gestational Age)

21.06 ± 9.90

(n = 228)

21.64 ± 10.45

(n = 106)

0.63

-

After you reduced your training

schedule, did you continue to train?

Yes

88%

(n=195/221)

80%

(n=84/105)

0.06

1.88 [0.98 – 3.47]

Olympic lifting

Engaged in during pregnancy

77%

(n=228/298)

62%

(n=86/139)

0.002

2.01 [1.31 – 3.12]

Engaged until ___ weeks of gestation

29.88 ± 8.41

30.79 ± 8.12

0.38

-

Valsalva

Engaged in during pregnancy

41%

(n=119/291)

18%

(n=24/135)

<0.0001

3.20 [1.93 – 5.32]

Engaged until ___ weeks of gestation

29.54 ± 10.12

31.13 ± 9.50

0.47

-

Supine weightlifting

Engaged in during pregnancy

100%

(n=307/307)

NA

-

Engaged until ___ weeks of gestation

27.69 ± 9.29

NA

0.09

-

Weightlifting belt

Engaged in during pregnancy

13%

(n=39/300)

5%

(n=7/138)

0.01

2.80 [1.27 – 6.65]

Engaged until ___ weeks of gestation

16.65 ± 8.02

23.43 ± 13.51

0.26

Weightlifting Done During

Pregnancy

Days per week

3.14 ± 1.18

(n = 184)

2.52 ± 1.04

(n = 79)

<0.0001

-

Duration per session

44.86 ± 18.56

(n = 180)

42.93 ± 16.46

(n = 75)

0.41

-

RPE

5.52 ± 1.21

(n = 172)

5.30 ± 1.23

(n = 69)

0.22

-

1%RM

61.03 ± 13.09

(n = 146)

55.96 ± 17.49

(n = 57)

0.05

-

Pregnancy Moderate Intensity

Aerobic Training

Days per week

3.71 ± 1.46

(n = 184)

3.80 ± 1.73

(n = 78)

0.71

-

Duration per session

34.23 ± 14.53

(n = 181)

40.80 ± 15.25

(n = 75)

0.002

-

Pregnancy Vigorous Intensity

Aerobic Training

Days per week

2.32 ± 1.33

(n = 111)

2.04 ± 1.40

(n = 51)

0.24

-

Duration per session

24.41 ± 14.33

(n = 110)

30.61 ± 17.37

(n = 49)

0.032

-

Table 16. Postpartum Training Outcomes. Data presented as mean ± SD or n (%).

Returned to training ___ month(s) postpartum (n =

400)

3.15

2.97

Did not return (n = 47)

My body has not yet recovered

19

40%

I did not want to

2

4%

I did not have time

11

23%

Other

15

32%

Return to Weightlifting

Olympic Lifts

Returned ___ months postpartum (n = 300)

4.0 ± 3.4

Did not return

72

19%

Valsalva

Returned ___ months postpartum (n = 213)

4.5 ± 3.6

Did not return

128

38%

Weightlifting belt

Returned ___ months postpartum (n = 120)

5.8 ± 4.5

Did not return

180

60%

Table 17. Prenatal urinary incontinence vs continence postpartum training outcomes. Data presented as mean ± SD or n (%). Total respondents

429 including 159 experiencing urinary incontinence during pregnancy and 270 not.

Prenatal urinary

incontinence

Prenatal continence P Value OR [95% CI]

Returned to training ___ month(s)

postpartum

3.05 ± 3.00

(n = 146)

3.21 ± 2.97

(n = 246)

0.62

-

Did not return to training postpartum

9%

(n=15/161)

10%

(n=28/274)

0.87

1.11 [0.58 to 2.08]

My body has not yet recovered

40%

(n=6/15)

39%

(n=11/28)

>0.99

1.03 [0.31 to 3.66]

I did not want to

0%

(n=0/15)

7%

(n=2/28)

0.53

0.00 [0.00 to 4.03]

I did not have time

33%

(n=5/15)

18%

(n=5/28)

0.28

2.30 [0.54 to 9.97]

Other

27%

(n=4/15)

36%

(n=10/28)

0.74

0.65 [0.19 to 2.58]

Olympic Lifts

Returned ___ months postpartum

4.1 ± 3.8

(n= 103)

3.9 ± 3.2

(n = 191)

0.72

-

Did not return

24%

(n=32/135)

17%

(n=38/229)

0.10

1.56 [0.93 – 2.63]

Valsalva

Returned ___ months postpartum

5.1 ± 4.6

(n = 77)

4.3 ± 2.9

(n = 130)

0.12

-

Did not return

41%

(n=53/130)

37%

(n=75/205)

0.49

1.19 [0.76 – 1.87]

Weightlifting belt

Returned ___ months postpartum

6.8 ± 5.2

(n = 37)

5.3 ± 4.0

(n = 80)

0.09

-

Did not return

67%

(n=76/113)

56%

(n=102/182)

0.07

1.61 [0.99 – 2.62]

Table 18. Postpartum urinary incontinence vs continence postpartum training outcomes. Data presented as mean ± SD or n (%). Total respondents

423 including 241 experiencing urinary incontinence postpartum and 182 not.

Postpartum Urinary

Incontinence

Postpartum

Continence

P Value OR [95% CI]

Returned to training ___ month(s)

postpartum

3.29 ± 3.26

(n = 229)

2.98 ± 2.55

(n = 161)

0.30

-

Did not return to training postpartum

7%

(n=17/246)

14%

(n=26/187)

0.02

0.46 [0.24 to 0.86]

My body has not yet recovered

35%

(n=6/17)

38%

(n=10/26)

>0.99

0.87 [0.27 to 2.99]

I did not want to

0%

(n=0/17)

8%

(n=2/26)

0.51

0.00 [0.00 to 3.29]

I did not have time

41%

(n=7/17)

15%

(n=4/26)

0.08

3.85 [0.82 to 13.47]

Other

24%

(n=4/17)

38%

(n=10/26)

0.34

0.49 [0.15 to 1.88]

Olympic Lifts

Returned ___ months postpartum

4.25 ± 3.89

(n= 174)

3.52 ± 2.33

(n = 120)

0.06

-

Did not return

19%

(n=40/214)

20%

(n=30/229)

0.79

1.09 [0.64 to 1.86]

Valsalva

Returned ___ months postpartum

4.80 ± 4.01

(n = 115)

4.19 ± 3.07

(n = 93)

0.23

-

Did not return

40%

(n=78/193)

34%

(n=48/141)

0.25

0.76 [0.48 to 1.19]

Weightlifting belt

Returned ___ months postpartum

6.30 ± 4.46

(n = 66)

5.04 ± 4.42

(n = 52)

0.13

-

Did not return

60%

(n=100/166)

59%

(n=75/127)

0.90

0.95 [0.60 to 1.52]

Table 19. Prenatal Olympic weightlifting participation vs no participation postpartum training outcomes. Data presented as mean ± SD or % (n).

Total respondents 426 including 302 engaging in Olympic weightlifting during pregnancy and 124 not.

Engaged in Olympic

weightlifting

Did not engage in

Olympic

weightlifting

P Value

OR [95% CI]

Returned to training ___ month(s)

postpartum

2.99 ± 2.83

(n = 286)

3.73 ± 2.55

(n = 99)

0.03

-

Did not return to training postpartum

5%

(n=16/302)

17%

(n=20/119)

0.0004

0.28 [0.14 to 0.55]

My body has not yet recovered

50%

(n=8/16)

35%

(n=7/20)

0.50

1.86 [0.46 to 6.24]

I did not want to

0%

(n=0/16)

10%

(n=2/20)

0.49

0.00 [0.00 to 2.67]

I did not have time

25%

(n=4/16)

25%

(n=5/20)

>0.99

1.00 [0.26 to 4.77]

Other

25%

(n=4/16)

30%

(n=6/20)

>0.99

0.78 [0.21 to 3.15]

Return to weightlifting

Olympic Lifts

Returned ___ months postpartum

3.60 ± 2.76

(n= 273)

8.41 ± 6.57

(n = 22)

<0.0001

-

Did not return

8%

(n=40/296)

74%

(n=30/85)

<0.0001

0.29 [0.16 to 0.51]

Valsalva

Returned ___ months postpartum

4.26 ± 3.36

(n = 174)

6.10 ± 4.92

(n = 30)

0.01

-

Did not return

32%

(n=82/256)

61%

(n=46/76)

<0.0001

0.31 [0.18 to 0.52]

Weightlifting belt

Returned ___ months postpartum

5.83 ± 4.65

(n = 106)

6.56 ± 3.54

(n = 9)

0.65

-

Did not return

53%

(n=119/225)

87%

(n=59/68)

<0.0001

0.17 [0.08 to 0.35]

Table 20. Prenatal Valsalva maneuver participation vs no participation postpartum training outcomes. Data presented as mean ± SD or % (n).

Total respondents 418 including 142 participating in Valsalva during pregnancy 276 not.

Engaged in Valsalva

Did not engage in

Valsalva

P Value

OR [95% CI]

Returned to training ___ month(s)

postpartum

2.68 ± 2.43

(n = 130)

3.39 ± 3.23

(n = 246)

0.02

-

Did not return to training postpartum

8%

(n=12/142)

10%

(n=28/274)

0.60

0.81 [0.41 – 1.66]

My body has not yet recovered

42%

(n=5/12)

46%

(n=13/28)

>0.99

0.82 [0.21 to 3.58]

I did not want to

33%

(n=4/12)

25%

(n=7/28)

0.70

1.50 [0.40 to 5.88]

I did not have time

8%

(n=1/12)

4%

(n=1/28)

0.52

2.46 [0.12 to 48.08]

Other

17%

(n=2/12)

25%

(n=7/28)

0.70

0.60 [0.11 to 3.04]

Return to weightlifting

Olympic Lifts

Returned ___ months postpartum

3.5 ± 3.0

(n= 102)

4.3 ± 3.7

(n = 183)

0.051

-

Did not return

16%

(n=19/121)

21%

(n=49/232)

0.26

0.70 [0.39 – 1.24]

Valsalva

Returned ___ months postpartum

3.7 ± 2.8

(n = 110)

5.5 ± 4.2

(n = 97)

0.0005

-

Did not return

15%

(n=19/129)

52%

(n=106/203)

<0.0001

0.16 [0.09 – 0.27]

Weightlifting belt

Returned ___ months postpartum

5.6 ± 4.6

(n = 52)

6.0 ± 4.3

(n = 60)

0.62

-

Did not return

53%

(n=59/111)

66%

(n=118/178)

0.03

0.58 [0.35 – 0.94]

Table 21. Prenatal supine weightlifting participation vs no participation postpartum training outcomes. Data presented as mean ± SD or % (n).

Total respondents 448 including 307 participating in supine weightlifting during pregnancy 141 not.

Engaged in supine

weightlifting

Did not engage in

supine weightlifting

P Value

OR [95% CI]

Returned to training ___ month(s)

postpartum

2.98 ± 2.65

(n = 275)

3.47 ± 3.52

(n = 122)

0.18

-

Did not return to training postpartum

8%

(n=23/298)

12%

(n=16/138)

0.21

0.64 [0.32 – 1.23]

My body has not yet recovered

48%

(n=11/23)

50%

(n=8/16)

>0.99

0.92 [0.25 to 3.36]

I did not want to

4%

(n=1/23)

6%

(n=1/16)

>0.99

0.68 [0.03 to 13.75]

I did not have time

22%

(n=5/23)

18%

(n=3/16)

>0.99

1.20 [0.23 to 5.16]

Other

26%

(n=6/23)

25%

(n=4/16)

>0.99

1.06 [0.27 to 3.90]

Return to weightlifting

Olympic Lifts

Returned ___ months postpartum

3.7 ± 2.8

(n= 215)

4.6 ± 4.4

(n = 86)

0.07

-

Did not return

17%

(n=43/258)

27%

(n=32/118)

0.03

0.54 [0.32 – 0.90]

Valsalva

Returned ___ months postpartum

4.2 ± 3.5

(n = 163)

5.7 ± 4.3

(n = 49)

0.04

-

Did not return

33%

(n=82/245)

51%

(n=50/99)

0.005

0.49 [0.31 – 0.79]

Weightlifting belt

Returned ___ months postpartum

5.6 ± 4.8

(n = 88)

6.3 ± 3.8

(n = 35)

0.37

-

Did not return

58%

(n=123/211)

62%

(n=57/92)

0.61

0.86 [0.52 – 1.44]

Table 22. Advice Received About Weightlifting During and Following Pregnancy. Data presented as mean ± SD or n (%).

Did you speak to your healthcare provider about

weightlifting during pregnancy? (n = 425)

Yes

278

65%

No

147

35%

Advice Given During Pregnancy from Health Care

Provider (n = 276)

Continue heavy lifting without modification

27

10%

Continue heavy lifting with modification

169

61%

Stop heavy lifting

40

14%

Other

40

14%

Did you see a pelvic floor physiotherapist prior-to

or following birth? (n = 426)

Yes, before birth

18

4%

Yes, after birth

114

27%

Yes, before and after birth

84

20%

No

190

45%

I plan on seeing a pelvic floor physiotherapist

20

5%

Advice Given During Pregnancy from

Physiotherapist (n = 205)

Continue heavy lifting without modification

15

7%

Continue heavy lifting with modification

147

72%

Stop heavy lifting

16

8%

Other

27

13%

Other Resources for Heavy Lifting During

Pregnancy (n = 421)

No

64

15%

Friends

21

5%

Family

6

1%

Coach

112

27%

Internet

166

39%

Books

12

3%

Other

40

10%

QUESTIONNAIRE

Demographics

1) Current date

2) Year of birth

3) Current location (country from a dropdown list)

Sporting career:

4) What sport(s) did you train for that included heavy weightlifting (>80% of 1RM)?

5) How many years have you trained in heavy weightlifting?

6) Please indicate the highest level you trained or competed at (for example, I was a

weightlifter at the Olympic games, I was a recreational athlete).

a. Recreational athlete

Impact of heavy resistance training on pregnancy and postpartum health outcomes

Abstract and Figures