A randomized controlled trial evaluating the effect of ethinyl estradiol during clomiphene citrate cycles among women with polycystic ovary syndrome.

Objective: To investigate the effects of low-dose ethinyl estradiol (EE) on the clinical pregnancy rate among women with polycystic ovary syndrome (PCOS) undergoing ovulation induction with clomiphene citrate (CC).

Methods: Between March 12, 2011, and February 10, 2013, a randomized, double-blind, placebo-controlled trial was conducted at the Royan Institute Research Center, Tehran, Iran, among women with PCOS who were aged 25-30 years, were undergoing their first intrauterine insemination cycle, and had a history (≥2 years) of infertility, oligomenorrhea, or amenorrhea. Participants were randomly allocated to receive EE (0.05 mg daily for 5 days) or placebo, co-administered with CC cycles (100 mg daily for 5 days). The primary outcome was clinical pregnancy rate. Analyses were per protocol: patients who discontinued the intervention were excluded.

Results: Analyses included 45 women who received CC and EE, and 50 women who received CC and placebo. The number of women who achieved a clinical pregnancy was higher among participants who received CC and EE (13 [29%]) than among those in the control group (5 [10%]; P =0 .02). No adverse effects of EE were reported.

Conclusion: The combination of CC and EE seems to increase the clinical pregnancy rate among women with PCOS undergoing intrauterine insemination. ClinicalTrials.gov:NCT01219101.