The luteal phase has been defined as the period between ovulation and either the establishment of a pregnancy or the onset of menses two weeks later. Luteal phase defect (LPD) has been attributed mainly to inadequate production of progesterone (P) that is known as the major product of the corpus luteum, which is necessary for the establishment of pregnancy. As a result, P has been used as luteal phase support (LPS) in ovulation induction cycles for many years (
LPD has been reported in patients with polycystic ovarian syndrome (PCOS) that has been identified as most common endocrine disorder in women of reproductive age (
On the other hand, controlled ovarian hyperstimulation is generally used as treatment protocols for patients with PCOS. In controlled ovarian hyperstimulation cycles, multifollicular development and supraphysiologic steroid serum concentrations may negatively affect luteinizing hormone (LH) secretion. Disturbed LH secretion may induced LPD that leads to premature luteolysis, reduced LH concentration, low P level and shortened luteal phase (
Some studies have been shown that presence of LPS through administration of P has significantly affected the success of ovarian induction and intrauterine insemination (IUI) cycles (
Therefore, the previous studies have produced conflicting results, while the amount of data from well-controlled clinical trials is limited. Thus, further studies are required to describe the impact of treatment with P for LPS in stimulated cycles in PCOS before deciding to move forward with more invasive assisted reproductive technologies.
To best our knowledge, there had been no prospective trial investigating the need for P administration in the combination stimulation protocols in PCOS. In light of these observations, the aim of present study was to evaluate the effect of LPS with P on pregnancy rate in Iranian women with PCOS who were treated with either CC or letrozole in combination with human menopausal gonadotropin (HMG).
A randomized clinical trial with parallel design was employed to confirm the effect of LPS with P on pregnancy rate in patients with PCOS. This study was conducted in an infertility clinic affiliated with Shahid Beheshti Hospital in Kashan, Isfahan Province, central part of Iran, between Aprils and January 2011.
Patients were eligible if they met following criteria: being 20-35 years of age; being married; not having non-classical adrenal hyperplasia, thyroid disorders and hyperprolactinemia; being Iranian; having effective speaking or listening skills; not having male factor for infertility; having normal uterine cavity and patency of fallopian tube as demonstrated by either hysterosalpingography (HSG) or diagnostic laparoscopy and hysteroscopy; and having Rotterdam diagnostic criteria. Based on random allocation sequence generated by one of researchers, enrolled participants (n=198) were divided into two main groups as follows: i. CC group (n=98) used a combination consisting of CC and HMG and ii. letrozole group (n=100) used a combination consisting of letrozole and HMG (
Patients flow chart.
On day 3 of the treatment cycle, baseline transvaginal ultrasounds scan (AU 350, Esaote, Milano, Italy) was performed. One physician carried out all sonograms and treatment protocols. The endometrial stripe was measured at its maximum anteroposterior thickness along the sagital axis of the uterine body. When there was no ovarian cyst on the scan, CC group received orally 100 mg clomiphene citrate (CC; Iran Hormone,Tehran, Iran) for 5 days starting on day 3 of the menstrual cycle, while letrozole group received 5 mg/day of letrozole (Femara; Novartis Pharma AG, Switzerland) from day 3 to day 7 of the menstrual cycle. It is noted that HMG contains follicle-stimulating hormone (FSH) and LH. The dose and duration of HMG treatment was adjusted according to the patient's response, after monitoring the follicular development including the number of growing follicles. Therefore, in both groups, at least 5 ampoules (Merional, IBSA, Switzerland) in total dosage of 150 IU containing FSH were applied intramuscularly (IM) daily from day 5 to day 10. After day 10 of the menstrual cycle, all patients were evaluated every other day by a transvaginal ultrasound. When one or more dominant follicle(s) reached .18 mm, ovulation was triggered in form of an IM injection of 5000 IU human chorionic gonadotropin (hCG) (Choriomon, IBSA, Switzerland). Afterward, all patients (n=245) were randomly divided into two sub-groups. The patients (n=122) who used P suppositories (Cyclogest, 400 mg vaginally; Alpharma, England) were included in LPS group, while the rest (n=123) who did not use the supplement were included in non-P cycles group. LPS group used P suppositories daily starting on the day after hCG and was continued for 14 consecutive days.
Outcome measure was the sign of chemical pregnancy (positive β-hCG test i.e. >25 IU/mL). Pregnancy testing was performed by determining the quantitative serum βhCG level on day 14 after P administration.
For an expected pregnancy rate of 21% for patients with LPS and 12% for patients without LPS, a sample size of 50 patients per groups was required for a statistical power of 90% at a p level of 0.05. Socio-demographic characteristics of the groups were expressed as mean ± SD or case (percentage) elsewhere, while the collected data were compared using one-way analysis of variance (One-Way ANOVA) and Chi-squared tests. Comparison of chemical pregnancy between groups was performed by chi-squared test. Multivariable logistic regression was specified to evaluate association between pregnancy rate after LPS and variables of interest. The Statistical Package for Social Sciences (SPSS; SPSS Inc., Chicago, IL, USA) version 11.5 was used to assess the study data. P values were set as 0.05 for all analyses.
The Ethics Committee of the Kashan Medical University approved the study. The protocol was explained to the patient's before they entered the study, while an informed consent was obtained from all.
We included 198 participants in the present study, who had completed treatment and follow up. The socio-demographic characteristics between groups were compared according to age, duration of infertility, endometrial thickness and number of dominant follicle. Results showed that there were no significant differences between the groups except for the age (
Socio-demographic characteristics of participants in CC and letrozole groups with and without using P
|Variable||CC (n=98)||Letrozole (n=100)|
|Using P||Not using P||Using P||Not using P|
Progesterone supplementation was resulted in 10% higher pregnancy rate in LPS group than in non-P cycles group, although this difference did not reach statistical significance (p=0.08). LPS improved pregnancy rate in both CC (11 vs. 7, p=0.30) and letrozole (14 vs. 8, p=0.10) groups, although the difference is not significant. In addition, patients who used letrozole for ovulation induction had higher pregnancy rates when using intravaginal P support than CC group (14 vs. 11, p=0.40), although the difference is not significant.
To conduct thorough analysis on effect of P supplementation on the pregnancy rate with consideration of other confounders, we applied logistic regression. The effect of the parameters (
Logistic regression used as a dependent variable for the achievement of pregnancy
|Dependent variable: incidence of pregnancy||P value||SE||Odds ratio||95% CI|
Currently, no information is available regarding the effect of LPS using P supplementation on pregnancy rate in stimulated cycles with combination therapies. This is the first study in which the effect of LPS with P on pregnancy rate was evaluated in Iranian women with PCOS who were treated with either CC or letrozole in combination with HMG for ovulation induction. Progesterone supplementation seemed to be of benefit in both the CC and letrozole treatment groups. The women with PCOS may inherently benefit from P supplementation in the luteal phase regardless of which medication is used for ovulation induction. P administration in PCOS patients has been demonstrated to decrease LH pulse frequency (
While development of several follicles to attain ovulation and large amounts of P are the main cause of the ovarian stimulation, the treatment overrides the physiological feedback mechanisms. The luteal phase of these cycles is characterized by a momentary high level of one or both hormones, which suppress the levels of LH and FSH (
In Balasch colleagues’ study (
It has been proposed that in IVF cycles, the use of GnRH analogs and gonadotropins cause multifollicular development, change of the hormonal environment, an increase in steroid serum concentration and an increase in risk of LPD (
Tavanitou et al. (
In addition, in present study, patients who used letrozole for ovulation induction had higher pregnancy rates when using P as compared to CC group. Studies on effect of P supplementation in patients with PCOS using either CC or letrozole are limited. In a study by Montville et al. (
These observations would help to explain the benefits of CC, letrozole and HMG on the luteal phase that showed no significant relation in present study. Whether non-significant result is due to lack of LPD in mildly stimulated cycles (
Strengths of this study included matching properties such as duration of infertility, endometrial thickness and number of dominant follicles, indicating these confounders did not play a role in results. In addition, our trial included the same physician using the same clinical protocols for all patients. Most importantly, all patients followed the same lab protocols. We had attempted to adjust the results for parameters that were significantly different between the two study groups, but our conclusions are influenced by some limitation.
The obvious weakness is small sample size that did not provide an adequately powered analysis for the important confounders, so the tested outcome could be affected (pregnancy rate). Moreover, the lack of statistical significance of difference between groups in present study may be a result of not having the number of cycles required to reach appropriate statistical power. Perhaps the failure to observe a significant effect of P on pregnancy rate in the different studies may be explained in part by either small study sizes, inadequate statistical power to detect a significant difference, the use of different drugs for ovarian stimulation, as well as different types and dosages of P for LPS. Despite these limitations, our findings were the subject of thorough statistical analysis that added strength to our conclusions.
Undoubtedly there is a need for further prospective randomized studies, with larger samples and longer periods of follow-up, to confirm the real clinical benefit of luteal phase P administration (if any) before it is introduced into daily clinical practice.
Our results suggest that LPS with P may improve pregnancy rate in PCOS patients treated with either CC or letrozole in combination with HMG.