Use of ethinyl estradiol to reverse the antiestrogenic effects of clomiphene citrate in patients undergoing intrauterine insemination: a comparative, randomized study

Objective: To compare the effectiveness of clomiphene citrate used alone and in combination with ethinyl E-2 for the induction of ovulation in patients undergoing IUI. Design: Randomized, double-blind study. Setting: Four infertility treatment centers. Patient(s): Women aged 25-35 years with infertility of at least 2 years' duration and oligomenorrhea or amenorrhea associated with a positive menstrual response to an IM progesterone challenge. Intervention(s): A total of 64 patients were randomized to treatment with CC (100 mg daily for 5 days) or CC (100 mg daily for 5 days) plus ethinyl E-2 (0.05 mg daily for 5 days). Main Outcome Measure(s): The uterine artery pulsatility index, number of preovulatory follicles, endometrial thickness, and pregnancy rate. Result(s): Both treatment regimens increased FSH, LH, and 17 beta-E-2, levels, with no statistically significant differences. There was a statistically significant difference in endometrial thickness between the two treatment groups. No statistically significant differences were noted in pulsatility index values or in the number of preovulatory follicles. Conclusion(s): Ethinyl E-2 can reverse the deleterious effects of CC on endometrial thickness, which may contribute to higher pregnancy rates. (Fertil Steril(R) 2000;73:85-9. (C) 1999 by American Society for Reproductive Medicine.)