Evaluation of Inhibition of Antiestrogenic Effect of Clomiphene Citrat on Endometrium by Using Ethinyl Estradiol

  Background & Objective : Clomiphene is an effective and cheap drug in induction of ovulation or super ovulation in infertile women. Although it induced ovulation in 80-90% of cases, pregnancy rate is 30-40% due to anti Estrogenic effect on endometrial and mucosal cervix. The goal of this research is to evaluate the inhibition of antiestrogenic effect of clomiphene citrate by using of ethinyl estradiol. Materials & Methods: A double blind clinical trial was performed in 62 infertile patients. They were 20-35 years old and 3 months before treatment they didn’t used any drugs for their infertility. They had BMI < 30 and in normal range of FSH, LH, TSH, PRL and testosterone on the third days of menstrual cycle. They were randomly divided into two groups A and B. Group A received 100 mg/day clomiphene citrate in the 5th day of menstrual cycle for 5 days and 0.05 mg/day ethinyl estradiol for 5 days from 8th day of menstrual cycle. Group B received only clomiphene citrate 100 mg/day in the 5th day of menstrual cycle for 5 days. Patients whom have follicles growth of greater than 18 mm have prescribed 10,000 HCG and 36 hours later IUI was performed for all patients. Results: Our results show that pregnancy rate in patients who received clomiphene citrate plus ethinyl estradiol was higher than patients who received only clomiphene citrate, 14.3% versus 9.7%, respectively. This difference is not significant. Mean size of dominant follicles in groups A was less than group B (p=0.0001) and cancellation rate was higher in group A (p=0.005). Endometrial thickness and appearance in two groups was similar. Conclusion: Although ethinyl estradiol could not either increased endometrial thickness or improved endometrial appearance. It could not also decrease follicular growth rate that to our best knowledge was not reported previously. But it could increase pregnancy rate from 9.7% to 14.3%. Although this differences is not significant (p=69%) it is important from clinical point. This difference may be due to differences in etiology of infertility between two groups or other causes. More studies are needed in future.