The effect of time of initiation of clomiphene citrate on multiple follicle development for human in vitro fertilization and embryo replacement procedures.

Clomiphene citrate has been utilized for ovarian stimulation for human in vitro fertilization and embryo replacement (IVF-ER) procedures quite successfully. The optimal time and the amount of drug necessary for optimal development have not been identified. In this investigation, 58 patients participating in a human IVF-ER program were stimulated with clomiphene citrate, 150 mg/day for 5 days, beginning on day 3, 4, 5, or 7 of the menstrual cycle. Maximal numbers of oocytes recovered, fertilized, and transferred occurred when stimulation was initiated on the fifth day of the cycle. It is concluded that if clomiphene alone is utilized for multiple follicle development, cycle day 5 is optimal for drug initiation.