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Original Article
Low progesterone levels and ovulation by ultrasound assessment
in infertile patients
Eliane G. M. Sanchez1, Christiane R. Giviziez1, Hugo M. Sanchez1, Patrícia L. S. Agostinho1, Patrícia S. Barros1,
Mário S. Approbato2
1Federal University of Goiás. Medical School. University Hospital. Gynecology and Obstetrics Department.
Human Reproduction Lab - Goiânia (GO) - Brazil
2Federal University of Goiás – Jataí (GO) - Brazil
ABSTRACT
Objective: To assess the correlation between low levels
of progesterone and ovulation by ultrasound monitoring in
infertile patients with regular menstrual cycles.
Methods: Case-control study. The sample consisted of
302 women aged 20-40 years, treated from 2000 to 2014
in the Human Reproduction Laboratory of the University
Hospital of the Federal University of Goiás and in the De-
partment of Gynecology and Obstetrics in Goiânia, Goiás.
Data collection was performed by analysis of physical re-
cords (Medical Records and Health Information Services)
and electronic ones (Sisfert©, 2004) after approval by a
Human Research Ethics Committee. Patients were clas-
sied according to their ovulatory status, evaluated by
progesterone levels and ultrasound monitoring and divid-
ed into two groups: Group I (anovulatory cycle patients,
n=74) and Group II (ovulatory patients, n=228). In both
groups associations were made between the percentage
of patients with normal progesterone (≥ 10 ng/ml) and
percentage of patients with low progesterone (5.65 - 9.9
ng/ml). The groups were paired for comparisons related to
age, body mass index, duration of infertility, follicle stimu-
lating hormone (FSH), thyroid stimulating hormone (TSH),
luteinizing hormone (LH) and estradiol (E2).
Results: There was a signicant association between the
percentage of ovulation by ultrasound monitoring and the
percentages of patients who presented low levels of pro-
gesterone.
Conclusions: The study suggests that low serum levels of
progesterone are associated with low percentage of ovula-
tion in infertile women with regular menstrual cycles and
women with unexplained infertility.
Keywords: Infertility, Ovulation, Regular cycles, Low pro-
gesterone.
INTRODUCTION
The World Health Organization (WHO) denes infertility
as the absence of pregnancy after one year or more of sexual
relations with no use of contraceptives (Rowe et al., 1993).
It is estimated that there are from 50 to 80 million
infertile couples in the world, with about two million
new cases per year (Gonçalves, 2005). This event is ex-
perienced by 8-15% of couples in general. In Brazil,
more than 278,000 couples have some difculty in con-
ceiving a child at some point in their childbearing age.
The causes of infertility in women could be due to
anatomical factors related to the uterus or the fallopian
tubes; hormonal causes that affect the hypothalamic-pi-
tuitary-ovarian axis; and sterility without apparent cause
(ESCA). It is believed that these factors correspond to 35%
of infertility causes in women, 35% in men; 20% are asso-
ciated with female and male issues, and 10% with ESCA.
Ovulatory dysfunctions represent the main causes
of female infertility, accounting for up to 40% of them
(ASRM, 2012). Among the causes, hormonal changes
are the most important, especially for infertility. Among
them, we can highlight Polycystic Ovarian Syndrome
(PCOS), hypothyroidism, hyperprolactinemia, low levels
of progesterone (P4), among others (McLaren, 2012).
Progesterone (P4) is a hormone produced after puberty,
by the corpus luteum (CL) and by the placenta during the
pregnancy and it acts in the regulation of normal female re-
productive functions. The endometrium is prepared In the
womb, facilitating deployment and maintenance of early
pregnancy (Al-Asmakh, 2007). For this reason P4 plays a
vital role in female fertility and low levels of it can signi-
cantly decrease the chances of pregnancy due the proba-
ble inuence on endometrial development (ASRM, 2015).
P4 was rst associated with the corpus luteum by the
huge production of this steroid after ovulation. Currently, it
is known that its secretion starts from the moment a ma-
ture ovarian follicle is stimulated by LH release (Ke, 2014;
Moreira, 2014).
According to the ASRM (2012), ovulatory function can
be evaluated by assessing P4 levels in the bloodstream, but
it should be obtained at appropriate times in the menstrual
cycle.
It is usually recommended that P4 be dosed from 7 to
9 days after the suspected ovulation. Some authors con-
sider this event to happen with P4 levels starting at 3ng/
ml (Guttmacher et al., 1956; Garzia et al., 2004; ASRM,
2012; McLaren, 2012). The World Health Organization
(Rowe et al., 1993) stresses ovulatory P4 levels ≥ 5.65 ng/
ml, measured between the 20th and 24th days of a 28-day
cycle. Serum progesterone levels higher than 10 ng/ml are
used as a parameter to measure ovulatory function by the
ASRM (2012).
P4 levels may suffer discrete increases and cause the
non-rupture of a luteinized follicle (LUF). In this event, the
follicle develops itself normally, grows and matures, but
does not break to release the ovum; however, there may
be a P4 secretion, such as a follicle that brakes, originating
the CL. Thus, there is no ovulation, but the follicle secretes
P4, making serum levels increase slightly. In this case, val-
ues don’t reach the 10 ng/ml and it establishes a low level
of P4 (Van Zonneveld et al., 1994) causing anovulation.
Low P4 is one of the causes of anovulation and
a subtle cause of female infertility (Young & Lessey,
2010), which can be characterized by insufcient P4 se-
cretion to maintain the endometrium, preventing im-
plantation and normal embryo growth (Sonntag &
Ludwig 2012; Schliep, 2014). It can be found by P4
dosing and through invasive procedures or sophisticat-
ed ovulation assessment equipment (Mardesic, 1990).
There’s no standard characterization yet to evaluate
progesterone secretion during the luteal phase in nor-
mal fertile women and there is no established minimum
P4 value to determine an adequate luteal function. Fur-
thermore, it is known that the corpus luteum function var-
JBRA Assisted Reproduction 2016;20(1):13-16
doi: 10.5935/1518-0557.20160004
Received September 28, 2015
Accepted December 30, 2015 13
Original Article 14
Table 1. Distribution of patients according to LUF and Non-LUF groups comparison (confounding variables).
HC-UFG / Mater Clinic, Goiania 2000-2014.
General features LUF (n=74) Non-LUF (n=228) P
Age 31.54±4.71 31.85±4.21 0.32
BMI 24.83±3.85 23.88±3.93 0.07
LH 4.56±6.51 4.61±2.74 0.06
FSH 6.26±1.45 5.98±1.68 0.07
TSH 2.50±0.93 2.16±1.19 0.75
Estradiol (E2) 51.84±35.82 54.34±51.09 0.12
Infertility duration 67.61±47.81 64.17±46.95 0.28
BMI (Body Mass Index); LH (luteinizing hormone) FSH (Follicle Stimulating Hormone); TSH (thyroid-stimulating hormone)
ies from cycle to cycle, but if properly collected, serum
progesterone levels can be useful in clinical diagnosis to
assess the adequacy of the luteal phase (ASRM, 2015).
Some authors suggest that the diagnosis of decreased
P4 can be done by levels <10 ng/ml (Van Zonneveld et
al., 1994), others indicate values <8 ng/ml (Litwack &
Begley, 2001); and Arce et al. (2011) suggest values be-
tween 7.9 - 10 ng/ml may indicate LUF. Although there
is certain proximity between P4 values indicative of LUF,
there is still no consensus about low P4 threshold levels.
The identication of anovulatory cycles is a challenge
for healthcare professionals. Ovulation prediction or conr-
mation may also be obtained by serial monitoring through
transvaginal ultrasound, to measure follicle growth and
allow the evaluation of follicular rupture (ASRM, 2012).
Transvaginal US is of the gold standard for ovulation di-
agnosis during the menstrual cycle, but difcult to be used
in epidemiological studies. In the absence of this method,
measurements of concentrations of reproductive hormones
are commonly used to identify the ovulatory status in re-
search, among them the measure of P4 levels stands out.
A combination of methods for measuring ovulation
has been recommended in order to obtain a more accu-
rate diagnosis. The Labrep (Human Reproduction Labora-
tory) HC/UFG (University Hospital of the Federal Univer-
sity of Goiás) associates monitoring of ovarian follicles
through ultrasound and the dosage of P4 serum levels
to diagnose ovulation, although women with low P4 are
not necessarily submitted to ultrasound check, which
may be responsible for inconsistent ovulatory diagnos-
tics. This study is justied by the lack of literature show-
ing the low progesterone inuence in the ovulation of in-
fertile women with regular cycles. Thus, the aim of this
study was to evaluate the association between low levels
of P4 and US ovulation assessment in infertile patients
with regular cycles suffering from unexplained infertility.
MATERIALS AND METHODS
This is a case-control study. There were 302 patients
selected, aged between 20 and 40 years, seen between
2000 and 2014 in the Human Reproduction Laborato-
ry of the University Hospital of the Federal University of
Goiás/UFG and in the Clinic of Gynecology and Obstet-
rics of the private healthcare network in Goiania – Goias.
Data was collected from the medical charts
stored in the Medical Ofce Management Sys-
tem (SAMIS) and from the electronic charts from
the Sisfert© database, which started after approv-
al by the Human Research Ethics Committee HC/UFG.
Women who had been evaluated by ultrasound and had
presented both regular progesterone levels and ovulatory
cycles were included; women with FSH levels above 9.9
mIU/mL (basal FSH = 1.4 to 9.9 mIU/mL) were exclud-
ed, as were those with TSH higher than 4.7 (basal = 0,
4 and 5 mIU/L) (Garber et al., 2012), those with Poly-
cystic Ovarian Syndrome with oligomenorrhea or amen-
orrhea, users of medicines that would interfere with ovu-
lation and women under 20 and over 40 years of age.
The patients were broken down into two groups ac-
cording to their ovulatory state determined by transvag-
inal ultrasound monitoring: Group I (n=74) anovulatory,
comprising women who had P4 levels of 5.65 - 9.9 ng/ml
and lack of follicular collapse - evaluated by monitoring
with intravaginal US. Group II (n=228) ovulatory, consist-
ed of women with P4 levels ≥10 ng/mL and follicular col-
lapse evaluated by monitoring through US (ASRM, 2012).
Among those groups, two groups were evaluated to obtain
the percentage of patients with normal ovulatory proges-
terone (≥10 ng/mL) and the percentage of patients with
low progesterone (5.65 to 9.9 ng/mL) considered as LUF
in the study. Those groups were paired for comparison in
relation to age, body mass index, infertility duration, Folli-
cle Stimulating Hormone - FSH (ng/mL), Thyroid-stimulat-
ing Hormone - TSH (mIU/mL), Luteinizing Hormone - LH
(mIU/mL) Estradiol (E2) (pg/mL), according to Table 1.
The statistical analysis was performed using IBM
SPSS Statistics 20.0 (Statistical Packages for Social Sci-
ences, USA) and the Bioestat (version 5.3). We used the
Chi-square test with a condence interval of 95% and
P =0.05 for signicance level. Where the statistical anal-
JBRA Assist. Reprod. | V.20 | no1| Jan-Feb-Mar/ 2016
Table 2. Distribution of the second ovulation according to patients’ P4 levels (normal and 5.65 -9.9 ngml) from the
LabRep HC - UFG / Mater Clinic. Goiania, 2000-2014.
LUF (P4) Ovulation
(US)
Anovulation
(US)
Total X2P
Group I (LUF) 50 (20.4%) 24 (42.1%) 74 11.76 0.001
Group II (No LUF) 195 (79.6%) 33 (57.9%) 228
Total 245 57 302
P4 (progesterone); X2 (chi-square value). Group I - LUF (P4 5.65 - 9.9 ng/ml); Group II - No LUF (P4 ≥ 10 ng/ml). IC
95% (0.191 - 0.649). OR (odds ratio) = 0.353
Low levels of progesterone and ovulation - Sanchez, E 15
JBRA Assist. Reprod. | V.20 | no1| Jan-Feb-Mar/ 2016
ysis was not performed, we calculated the mean value
and the standard deviation of the variables under study.
RESULTS
The results obtained are presented in tables as fol-
lows. The comparability of the two populations stud-
ied is shown on Table 1. Comparability tests did not
show statistically signicant differences (P>0.05).
Table 2 shows a signicant association between the
percentage of ovulation through ultrasound and the per-
centage of patients who had low progesterone levels
(OR=0.353); IC (95%): 0.191 – 0.649. P=0.001.
DISCUSSION
This study has shown that low P4 levels are associ-
ated with signicant decreases in ovulation in infertile
women with regular cycles, women with unexplained
infertility. This fact was explained by Mesen & Young
(2015) when they reported that a defected luteal phase
may decrease P4 levels and the fertility in women.
It’s interesting to highlight that, despite the pul-
satile release of P4, its low levels on a single measure-
ment may not always indicate ovulatory disorders (ASRM,
2012). On the other hand, this present study found
ovulatory changes conrmed by monitoring through ul-
trasound in 42.1% of women who presented low P4.
Studies which evaluate P4 values in women with regular
cycles are unusual (Fatemi, 2009; Young & Lessey, 2010).
This study evaluated P4 levels in this group of women.
While normal P4 values are related to regular cycles and
ovulation, lower values may reect the presence of unrup-
tured luteinized follicle (LUF) (Schliep, 2014). In a study by
Litwack & Begley (2001) the ovulatory status was evaluat-
ed considering the P4 levels for three menstrual cycles in
543 patients with infertility history longer than two years.
From the population studied so far, 461 (90.2%) had nor-
mal ovulatory cycles conrmed by ultrasound monitoring
and 50 (9.8%) had anovulatory cycles. In this study, val-
ues considered suggestive of ovulation were the ones with
P4 levels > 8ng/ml, and P4 levels <8 ng/mL were con-
sidered low values. Out of the population being studied,
292 women (63.9%) had normal P4 and 165 (36.1%) had
low P4. From the group with apparently normal P4 values,
7.2% of women got pregnant when compared to 3.6% of
women with low P4. Our study showed signicant reduc-
tion (P <0.001) in the fertility of patients with low proges-
terone levels. It also corroborates the study by Hamilton et
al. (1987), who evaluated 201 ovulatory cycles in 170 in-
fertile women by measuring ovarian follicles through ultra-
sound and P4 levels. In our study we found LUF in 71% of
the cycles in which the P4 levels were lower than 10ng/ml,
and in 7.9% of cycles in which P4 levels were higher than
10ng/ml. These data corroborate the results of the present
study which also found LUF in cycles (20.4%) in which P4
levels were over 10ng/ml. Eissa et al. (1987) studied ovu-
latory cycles in 45 subfertile women and found LUF in 19%
of cycles, but neither reported P4 values used to determine
LUF, nor highlighted the monitoring of the ovulatory folli-
cle through US. The sensitivity and specicity of diagnostic
methods of ovulation were evaluated by Mesen & Young
(2015), wherein they found that P4 levels stand out among
other evaluating methods, including endometrial biopsy.
This study showed an association between an-
ovulation through ultrasound and low levels of P4.
CONCLUSIONS
This study suggests that low progesterone levels are
associated with a reduction in ovulation percentage in in-
fertile women with regular menstrual cycles and women
with unexplained infertility. The number (n) of women used
in the study favors greater emphasis on results found.
CONFLICT OF INTERESTS
No conict of interest have been declared.
Corresponding author:
Eliane Gouveia de Morais Sanchez
Universidade Federal de Goiás. Faculdade de Medicina.
Departamento de Ginecologia e Obstetrícia. Hospital das
Clínicas.
Laboratório de Reprodução Humana
Goiânia (GO) - Brasil.
E-mail: egmsio@yahoo.com.br
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