Comparison of two clomiphene citrate dosage regimens for follicular recruitment in an in vitro fertilization program.

Clomiphene citrate (CC) (150 mg/day) is used in most clinical in vitro fertilization and embryo transfer (IVF-ET) programs to induce maturation of several preovulatory follicles rather than the one characteristic of the unstimulated cycle. This study examines whether a reduced dosage of CC will induce the maturation of a similar number of follicles. The advantage of the reduced dosage should be a decrease in the dose-dependent antiestrogenic effects of CC. Normally ovulating women undergoing treatment in an IVF-ET program received CC on cycle days 5 to 9. Thirty-six patients received 150 mg/day, and 60 patients received 50 mg/day. There were no significant differences between the groups in the number or the size of follicles as measured by ultrasonography on the day of human chorionic gonadotropin administration. All seven clinical pregnancies were in the 50 mg group (P less than 0.05). These data suggest that there is no advantage to the 150 mg/day dosage of CC as compared with 50 mg/day with respect to enhanced follicular recruitment, and the higher dosage may have a detrimental effect on pregnancy establishment.