Time of initiation of clomiphene citrate and pregnancy rate in polycystic ovarian syndrome.

OBJECTIVE: To investigate whether the timing of clomiphene citrate (CC) administration affects hormonal levels, follicular growth, endometrial thickness, and ovulation and pregnancy rates in women with polycystic ovarian syndrome (PCOS). METHODS: Of the 78 infertile women with PCOS who participated in this prospective, double-blind, randomized clinical trial, 37 collectively underwent 71 cycles of CC (100 mg/day) on days 1 through 5 of the menstrual cycle (group 1) and 41 collectively underwent 73 cycles of CC at the same concentration on days 5 through 9 (group 2). Hormonal levels, follicular growth, endometrial thickness, and ovulation and pregnancy rates were compared. RESULTS: The mean number of follicles and the maximum follicular size were greater in group 2. However, ovulation rates were 72.8% in group 1 and 70.8% in group 2 (P=.78), and pregnancy rates were 40.5% in group 1 and 19.5% in group 2 (P=.04). CONCLUSION: Treatment with CC is associated with higher rates of pregnancy if started early (days 1-5) in the menstrual cycle.