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Work schedule and physically demanding work in relation to menstrual function: the Nurses’ Health Study 3
Abstract and Figures
This study aimed to evaluate occupational exposures and menstrual cycle characteristics among nurses.
Using cross-sectional data collected in 2010-2012 from 6309 nurses aged 21-45 years, we investigated nurses' menstrual function in the Nurses' Health Study 3. We used multivariable regression modeling to analyze the associations between occupational exposures and prevalence of irregular cycles and long and short cycle lengths.
The cohort reported cycle length as <21 (1.5%), 21-25 (15.6%), 26-31 (69.7%), and 32-50 (13.2%) days. In addition, 19% of participants reported irregular cycles. Working ≥41 hours/week was associated with a 16% [95% confidence interval (95% CI): 4-29%] higher prevalence of irregular cycles and a higher prevalence of very short (<21-day) cycles [prevalence odds ratio (OR) 1.93, 95% CI 1.24-3.01] in adjusted models. Irregular menstrual cycles were more prevalent among women working nights only (32% higher; 95% CI 15-51%) or rotating nights (27% higher, 95% CI 10-47%), and was associated with the number of night shifts per month (P for trend <0.0001). Rotating night schedule was associated with long (32-50 day) cycles (OR 1.28, 95% CI 1.03-1.61). Heavy lifting was associated with a higher prevalence of irregular cycles (34% higher), and the prevalence of cycles <21 days and 21-25 day cycles increased with increasing heavy lifting at work (P for trend <0.02 for each endpoint).
Night work, long hours, and physically demanding work might relate to menstrual disturbances.
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... 12 Among nurses, heavy lifting was associated with worse menstrual cramps, irregular cycles and short cycles; heavy physical exertion was associated with long cycles; and prolonged standing was associated with short cycles. [13][14][15] The goal of this study was to address methodological limitations of the epidemiological evidence regarding menstrual cycle irregularities among flight attendants, particularly related to confounder control and investigation of specific occupational exposures. We focused on two questions: if flight attendants have a higher prevalence of menstrual cycle irregularities than teachers, and if occupational physical demands are associated with menstrual cycle irregularities among flight attendants. ...
... For example, one of the largest studies of occupational physical exertion and menstrual cycle characteristics among nurses defined lifting as the frequency of lifting loads ≥25 pounds (≥11.3 kg) (0, 1-5, 6-15 or >15 times per day) and allowed study participants to self-define irregular cycles. 15 In contrast, we defined lifting as lifting a load of ≥15 pounds (≥6.8 kg) (0-5, 6-10, or >10 times per day) and irregularity as ≥8 days between the shortest and longest menstrual cycles within the past year. Despite these differences, our results are consistent with evidence from several studies indicating that frequent lifting is associated with greater menstrual pain and irregular menstrual cycles. ...
... Similarly, we did not have work hours in the analysis, which has previously been associated with cycle length. 15 Non-occupational factors such as nutrition and other potential predictors of menstrual cycles were also not considered and could contribute to residual confounding. ...
Objectives
Flight attendants perform physically demanding work such as lifting baggage, pushing service carts and spending the workday on their feet. We examined if more frequent exposure to occupational physical demands could explain why previous studies have found that flight attendants have a higher reported prevalence of menstrual cycle irregularities than other workers.
Methods
We conducted a cross-sectional analysis of 694 flight attendants and 120 teachers aged 18–44 years from three US cities. Eligible participants were married, had not had a hysterectomy or tubal ligation, were not using hormonal contraception and were not recently pregnant. Participants reported menstrual cycle characteristics (cramps, pain, irregular cycles, flow, bleed length, cycle length) and occupational physical demands (standing, lifting, pushing/pulling, bending/twisting, overall effort). We used modified Poisson regression to examine associations between occupation (flight attendant, teacher) and menstrual irregularities; among flight attendants, we further examined associations between occupational physical demands and menstrual irregularities.
Results
All occupational physical demands were more commonly reported by flight attendants than teachers. Flight attendants reported more frequent menstrual cramps than teachers, and most occupational physical demands were associated with more frequent or painful menstrual cramps. Lifting heavy loads was also associated with irregular cycles.
Conclusions
Occupational physical demands were associated with more frequent and worse menstrual pain among flight attendants. The physical demands experienced by these workers may contribute to the high burden of menstrual irregularities reported by flight attendants compared with other occupational groups, such as teachers.
... Among occupational characteristics, heavy lifting (lifting an object weighing ≥ 10 kg) was signifcantly associated with the occurrence of dysmenorrhea. Previous studies have also reported that heavy lifting increases the likelihood of experiencing irregular menstruation [39,40] and menstrual disorders among female nurses [18]. Heavy lifting appeared to have an adverse impact on women's menstrual health, highlighting the importance of preventing heavy lifting by female nurses in the workplace. ...
Aim: To examine the prevalence of dysmenorrhea in the predominantly female nursing profession and investigate the role of occupational characteristics in dysmenorrhea.
Background: Studies on working women have mostly examined the effects of dysmenorrhea symptoms on work performance, as opposed to shedding light on the association between work-related characteristics and dysmenorrhea.
Methods: In this cross-sectional study, we used data obtained from survey 9 of the Korea Nurses’ Health Study. The participants were female nurses of childbearing age. Statistical analysis included descriptive statistics and multivariable logistic regression.
Results: Data from 6697 participants were analyzed. Of the total sample, 47.3% had dysmenorrhea. After adjusting for confounders to examine the relationship between occupational characteristics and dysmenorrhea, the odds for dysmenorrhea were 1.230 times higher among women who lifted heavy objects at least six times a day compared to those who did not engage in heavy lifting (95% confidence interval: 1.028–1.473) and 1.042 times higher among women with higher physical fatigue (odds ratio: 1.042, 95% confidence interval: 1.023–1.061).
Conclusion: The findings clarify the potential for reducing dysmenorrhea through the improvement of work environment factors. Thus, this study may prove useful for developing educational programs and policies that aim to alleviate dysmenorrhea among working women, including nurses.
Implications for Nursing Management: Nursing managers and health policymakers need to understand the factors influencing dysmenorrhea and minimize female nurses’ physical burden by implementing appropriate nurse–patient ratios and improving their work environment.
... Circadian rhythms also play a role in fertility and pregnancy. Circadian disruption can detrimentally affect reproductive health, particularly in women where it can cause irregular menstrual cycle and decreased fertility (Lawson et al., 2011;Wang et al., 2016;Lawson et al., 2015;Mínguez-Alarcón et al., 2017). Circadian disruption also affects the estrous cycle in rats and mice (Miller and Takahashi, 2014). ...
The recurrent hormonal fluctuations within reproductive cycles impact sleep-wake behavior in women and in rats and mice used in preclinical models of sleep research. Strides have been made in sleep-related clinical trials to include equal numbers of women; however, the inclusion of female rodents in neuroscience and sleep research is lacking. Female animals are commonly omitted from studies over concerns of the effect of estrus cycle hormones on measured outcomes. This review highlights the estrous cycle’s broad effects on sleep-wake behavior: from changes in sleep macroarchitecture to regionally specific alterations in neural oscillations. These changes are largely driven by cycle-dependent ovarian hormonal fluctuations occurring during proestrus and estrus that modulate neural circuits regulating sleep-wake behavior. Removal of estrous cycle influence by ovariectomy ablates characteristic sleep changes. Further, sex differences in sleep are present between gonadally intact females and males. Removal of reproductive hormones via gonadectomy in both sexes mitigates some, but not all sex differences. We examine the extent to which reproductive hormones and sex chromosomes contribute to sex differences in sleep-wake behavior. Finally, this review addresses the limitations in our understanding of the estrous cycle’s impact on sleep-wake behavior, gaps in female sleep research that are well studied in males, and the implications that ignoring the estrous cycle has on studies of sleep-related processes.
... According to previous research, most patients with POI have experienced two or more adverse life events prior to diagnosis, suggesting that the cumulative negative effects of psychological stressors may play a role in the development of POI [4]. Long shifts and intense workloads are associated with menstrual disorders [5]. Lim Ym et al. reported that employed women were more likely to experience POI and early menopause than unemployed people [6]. ...
Premature ovarian insufficiency (POI) is a common gynecological endocrine disease, which seriously affects women’s physical and mental health and fertility, and its incidence is increasing year by year. With the development of social economy and technology, psychological stressors such as anxiety and depression caused by social, life and environmental factors may be one of the risk factors for POI. We used PubMed to search peer-reviewed original English manuscripts published over the last 10 years to identify established and experimental studies on the relationship between various types of stress and decreased ovarian function. Oxidative stress, follicular atresia, and excessive activation of oocytes, caused by Stress-associated factors may be the main causes of ovarian function damage. This article reviews the relationship between psychological stressors and hypoovarian function and the possible early intervention measures in order to provide new ideas for future clinical treatment and intervention.
... Fifty studies were excluded because 10 articles were non-English literature, 5 articles did not address the outcome of attention, 4 articles used univariate analysis methods, 13 articles had no extractable data, 11 articles were reviews, and 8 articles were conference abstracts. Finally, 21 articles met the inclusion criteria, among which 16 articles focused on menstrual disorders (Attarchi et al., 2013;Chung et al., 2005;Hatch et al., 1999;Jiang et al., 2019;Kwak & Kim, 2018;Labyak et al., 2002;Lawson et al., 2011Lawson et al., , 2015Lim et al., 2016;Mayama et al., 2020;Mirfat, 2016;Moen et al., 2015;Ok et al., 2019;Song et al., 2022;Su et al., 2008;Wang et al., 2016), 8 articles reported the occurrence of dysmenorrhea (Amilcar Albert-Sabater et al., 2016;Attarchi et al., 2013;Chiu et al., 2017;Chung et al., 2005;Jiang et al., 2019;Mayama et al., 2020;Mirfat, 2016;Sznajder et al., 2014), and 2 articles reported menopause (Khan et al., 2022;. ...
Background
Shift work is a potential risk factor for women's reproductive health. Evidence suggests that shift work is associated with menstrual disorders, reproductive disturbances, and adverse pregnancy outcomes. However, previous studies did not systematically examine the results of menstrual irregularities, dysmenorrhea, and early menopause at the same time.
Objective
To determine the relationship between shift work and women's menstrual characteristics (e.g., irregular menstruation, dysmenorrhea, and early menopause).
Methods
Four databases (PubMed, Embase, Cochrane, and Web of Science) were searched up to December 2022. The study characteristics and risk assessment values of the literature were extracted from 21 studies that met the criteria. Odds ratios (ORs), relative risks (RRs), hazard ratios (HRs), and 95% confidence intervals (CIs) were calculated to assess the relationship between shift work exposure and menstruation. The included studies were evaluated for heterogeneity, publication bias, sensitivity analysis, and subgroup analysis.
Results
A total of 21 studies with 195,538 female participants, including 16 cross-sectional studies and 5 cohort studies, were included in this meta-analysis. According to the quality evaluation, the included research had high methodological quality. The overall ORs of shift work for the likelihood of irregular menstruation and dysmenorrhea were 1.30 (95% CI, 1.23–1.36) (I² = 41.9%, P < 0.05) and 1.35 (95% CI, 1.04–1.75) (I² = 73.0%, P < 0.05), respectively. There was a significant positive association between shift work and the risk of early menopause (HR = 1.09, 95% CI, 1.04–1.14), without significant heterogeneity (I² = 0.0%, P > 0.05).
Conclusions
This meta-analysis indicated that shift workers have significantly higher odds of menstrual disorders, dysmenorrhea, and early menopause. This study focuses on female reproductive health and has broad implications for adjusting optimal working hours and shift schedules for female workers.
The methodological recommendations have been developed with the aim of grading, systematizing and identifying key areas for the implementation of individual measures or a comprehensive corporate program for reproductive health promotion in working individuals at the employer level, including taking into account international experience.
The guidelines describe seven key subprograms aimed at early diagnosis and timely treatment of urinary tract diseases, assessment of reproductive health, improving literacy in sex education and behavior, reducing the negative impact of industrial and external environmental factors on reproductive health, increasing commitment to measures to combat risk factors for noncommunicable diseases, providing support during menopause in women and andropause in men, and creating conditions in the workplace conducive to maintaining a strong family. The guidelines are intended for healthcare and public health organization specialists, heads of state authorities of constituent entities of the Russian Federation in the field of health protection, specialists of regional centers for public health and medical prevention, as well as for heads of organizations in various economic sectors. The materials presented in the guidelines can also be used by medical workers of various specialties (paramedics, general practitioners (family doctors), obstetrics and gynecology doctors, dermatology and venereology specialists, medical prevention doctors, occupational pathology physicians and urologists).
Objective:
To elucidate the presence, importance, and characteristics of menstrual changes related to stressful circumstances during the COVID-19 lockdown in Spain.
Study design:
An online survey was administered in Spain to menstruating women aged 15-55 who had not contracted COVID-19. It collected information on activities during the lockdown, sexual activity, perceptions of emotional status, any changes in menstrual characteristics, and impact on quality of life. The analysis of menstrual changes was limited to responders who did not use hormonal contraception.
Results:
A total of 6449 women answered the survey, and 4989 surveys were valid for the final analysis. 92.3% of women had at least one menstruation period during the lockdown, while 7.7% had amenorrhea. Quality of life (QoL) associated with menstruation worsened in 19% of women, did not change in 71.7%, and improved in 1.6%. For 50.1% of the women, global QoL worsened during the lockdown; 41.3% remained about the same and 8.7% reported improvement. Sexual activity during the lockdown decreased in 49.8% of the respondents, remained unchanged in 40.7%, and increased in 9.5%. As far the menstrual changes are concerned, there were no statistically significant differences in amenorrhea incidence, regularity of the menstrual cycle, or the amount or duration of menstrual bleeding in non-hormonal contraceptive users when evaluated by the length and characteristics of isolation, the perception of exposure to COVID-19 and the economic or employment situation. Conversely, we found statistically significant differences according to the intensity of changes in emotional status due to lockdown stressors and changes in regularity, duration, and heaviness of menstruation.
Conclusion:
Changes in emotional status, but not the length and intensity of the isolation or exposure to the disease, significantly influenced menstrual disturbances during the COVID-19 lockdown.
In this study, the characteristics of menstrual cycle in shift workers employed in the pharmaceutical industry are investigated.
This study was conducted in a pharmaceutical industrial complex in Tehran in 2012. 406 female workers in packaging units were studied on the menstrual cycle characteristics. The studied workers were divided into two groups of shift workers and non-shift workers and were compared in terms of the frequency of menstrual disorder (short-term cycle, long-term cycle, irregular cycle and bleeding during menstrual cycle) as well as hormonal values (FSH, LH, TSH, and Prolactin).
The odds ratio (OR) for menstrual disorder in the shift workers was 5.54 (95% CI=2.78-11.02) compared to the non-shift workers. The mean difference of hormonal values (except prolactin) between shift workers and non-shift workers was not significant (P>0.05).
This study suggests that shift work may disrupt the menstrual cycle.
Shift workers who experience sleep disturbances and exposure to light at night could be at increased risk for alterations in physiologic functions that are circadian in nature.
We investigated rotating shift work and menstrual cycle patterns in the Nurses' Health Study II using cross-sectional data collected in 1993 from 71,077 nurses aged 28-45 years who were having menstrual periods and were not using oral contraceptives. Log-binomial regression was used to estimate relative risks (RRs) and 95% confidence intervals (CIs).
Eight percent of participants reported working rotating night shifts for 1-9 months, 4% for 10-19 months, and 7% for 20+ months during the previous 2 years. Irregular cycles (>7 days variability) were reported by 10% of participants. Seventy percent of women reported menstrual cycles of 26-31 days, 1% less than 21 days, 16% 21-25 days, 11% 32-39 days, and 1% 40+ days. Women with 20+ months of rotating shift work were more likely to have irregular cycles (adjusted RR = 1.23 [CI = 1.14-1.33]); they were also more likely to have cycle length <21 days (1.27 [0.99-1.62]) or 40+ days (1.49 [1.19-1.87]) (both compared with 26-31 days). For irregular patterns and for 40+ day cycles, there was evidence of a dose response with increasing months of rotating shift work. Moderately short (21-25 days) or long (32-39 days) cycle lengths were not associated with rotating shift work.
Shift work was modestly associated with menstrual function, with possible implications for fertility and other cycle-related aspects of women's health.
To assess the validity of self-reported illnesses, medical records were reviewed for participants reporting major illnesses on the biennial follow-up questionnaires used in a prospective cohort study which began in 1976. In over 90% of cases of cancer of the breast, skin, large bowel, and thyroid, histopathology reports confirmed the subjects' self-report. Lower levels of confirmation were obtained for cancers of the lung, ovary, and uterus. Application of strict diagnostic criteria also gave lower levels of confirmation for myocardial infarction (68%) and stroke (66%). Among random samples of women reporting fractures and hypertension all records obtained confirmed self-reports. For self-reported elevated cholesterol levels 85.7% of self-reports were confirmed. Self-report is a valuable epidemiologic tool but may require additional documentation when the disease is diagnostically complex.
Numerous U. S. workers have work schedules different from the standard 9 a. m.-to-5 p. m., Monday-through-Friday, work shift; the demands of the industry are the chief determinant of the use of shift work and flexible schedules
: The role exerted by melatonin in human physiology has not been completely ascertained. Melatonin levels have been measured in different physiopathological conditions, but the effects induced by melatonin administration or withdrawal have been tested only recently. Some effects have been clearly documented. Melatonin has hypothermic properties, and its nocturnal secretion generates about 40% of the amplitude of the circadian body temperature rhythm. Melatonin has sleep inducing properties, and exerts important activities in the regulation of circadian rhythms. Melatonin is capable of phase shifting human circadian rhythms, of entraining free-running circadian rhythms, and of antagonizing phase shifts induced by nighttime exposure to light. Its effect on human reproduction is not completely clear, but stimulatory effects on gonadotropin secretion have been reported in the follicular phase of the menstrual cycle. Direct actions on ovarian cells and spermatozoa have been also documented. Beside these, new important actions for melatonin may be proved. Melatonin may exert protective effects on the cardiovascular system, by reducing the risk of atherosclerosis and hypertension, and may influence immune responses. Finally, by acting as an antioxidant, melatonin could be important in slowing the processes of ageing.
Background
Many chemical agents used in liquid crystal display (LCD) manufacturing have been evaluated in animal studies of female reproductive toxicity. Knowledge of their reproductive toxicity in humans is scant.AimsTo determine the effect of organic solvents on menstrual cycle characteristics of workers in LCD manufacturing.Methods
Cross-sectional study of female premenopausal workers in an LCD plant in Taiwan. Menstrual cycle characteristics were assessed from self-administered questionnaires, and chemical exposure was assessed using hand-held volatile organic compound (VOC) monitors with 24h canister sampling.ResultsThere was a response rate of 94%, and the final study population after exclusions was 288. Canister sampling found many chemical compounds with potential reproductive effects in the fabrication areas of the plant. Concentrations of total VOC were higher in the panel and module fabrication areas than in other areas of the plant. The prevalence of short menstrual cycles (>24 days) was higher in panel workers (adjusted odds ratio [OR]: 7.68; 95% confidence interval [CI]: 1.51-39.15) and module workers (adjusted OR: 8.38; 95% CI: 1.72-40.95) than in array fabrication workers and office workers.Conclusions
We found evidence for a possible link between repeated exposure to multiple organic solvents such as ethanol and acetone and increased prevalence of short menstrual cycles in premenopausal women.
Decreased basal body temperature measurements predict ovulation with an accuracy of 74%. The anovulatory cycle exhibits an ovarian monophasic pattern. This study evaluated the relationship between ovarian cycle pattern and sociodemographic characteristics, menstrual history and work characteristics of nurses in a Taiwan medical center.
Of 200 nurses recruited, 151 were analyzed. Each subject completed questionnaires and provided life recordings and daily basal body temperature measurements during the 14-week study.
The analytical results demonstrated that work place (P = 0.014) and work shift (P = 0.048) are significantly related to ovarian cycle pattern. Nurses who worked in emergent care units and wards had a higher prevalence of irregular ovarian cycle pattern. Approximately 53% of nurses who worked rotating shifts exhibited irregular ovarian cycle pattern.
Nurses who either had rotating shift work or worked in emergent care units and wards should be concerned with their own ovarian cycle pattern for their health.
The menstrual cycle is an important indicator of underlying hormonal function. Although menstrual cycle variability (sometimes referred to as 'regularity') is associated with a variety of demographic, behavioral, occupational, and environmental factors, as well as with several chronic diseases, few studies have examined its association with fecundity. We investigated whether a woman's menstrual cycle variability was associated with the likelihood of her achieving pregnancy. In this prospective study, we analyzed 3,536 menstrual cycles from 401 women (aged 19-41) recruited from 1990-1994. The women provided daily diaries recording menstrual bleeding, intercourse, and birth control use. Urine samples were assayed for human chorionic gonadotropin to identify early pregnancies during each menstrual cycle. Each woman's menstrual cycle variability was defined by the standard deviation of her cycle lengths during followup. The median follow-up was eight cycles. The outcome was her per-cycle probability of pregnancy. We found that women with high menstrual cycle variability had a reduced (51% lower) per cycle probability of pregnancy (fecundity ratio: 0.49; 95% confidence interval: 0.31, 0.77) compared with women with minimal variability. This relationship was independent of a woman's age and her mean cycle length. Thus, researchers and clinicians using menstrual cycle characteristics as indicators of endocrine or reproductive health should include measures of cycle variability in addition to the more commonly examined cycle length.
Physical exercise is known to strongly stimulate the endocrine system in both sexes. Among these hormones, androgens (e.g. testosterone, androstenedione, dehydroepiandrosterone) play key roles in the reproductive system, muscle growth and the prevention of bone loss. In female athletes, excessive physical exercise may lead to disorders, including delay in the onset of puberty, amenorrhoea and premature osteoporosis. The free and total fractions of circulating androgens vary in response to acute and chronic exercise/training (depending on the type), but the physiological role of these changes is not completely understood. Although it is commonly accepted that only the free fraction of steroids has a biological action, this hypothesis has recently been challenged. Indeed, a change in the total fraction of androgen concentration may have a significant impact on cells (inducing genomic or non-genomic signalling). The purpose of this review, therefore, is to visit the exercise-induced changes in androgen concentrations and emphasize their potential effects on female physiology. Despite some discrepancies in the published studies (generally due to differences in the types and intensities of the exercises studied, in the hormonal status of the group of women investigated and in the methods for androgen determination), exercise is globally able to induce an increase in circulating androgens. This can be observed after both resistance and endurance acute exercises. For chronic exercise/training, the picture is definitely less clear and there are even circumstances where exercise leads to a decrease of circulating androgens. We suggest that those changes have significant impact on female physiology and physical performance.
To assess salivary stress biomarkers (cortisol and α-amylase) and female fecundity.
Prospective cohort design.
United Kingdom.
274 women aged 18 to 40 years who were attempting pregnancy.
Observation for six cycles or until pregnancy: women collected basal saliva samples on day 6 of each cycle, and used fertility monitors to identify ovulation and pregnancy test kits for pregnancy detection.
Salivary cortisol (μg/dL) and α-amylase (U/mL) concentration measurements; fecundity measured by time-to-pregnancy and the probability of pregnancy during the fertile window as estimated from discrete-time survival and Bayesian modeling techniques, respectively.
Alpha-amylase but not cortisol concentrations were negatively associated with fecundity in the first cycle (fecundity odds ratio=0.85; 95% confidence interval 0.67, 1.09) after adjusting for the couples' ages, intercourse frequency, and alcohol consumption. Statistically significant reductions in the probability of conception across the fertile window during the first cycle attempting pregnancy were observed for women whose salivary concentrations of α-amylase were in the upper quartiles in comparison with women in the lower quartiles (highest posterior density: -0.284; 95% interval -0.540, -0.029).
Stress significantly reduced the probability of conception each day during the fertile window, possibly exerting its effect through the sympathetic medullar pathway.