The utility of a midcycle follicle-stimulating hormone boost in addition to human chorionic gonadotropin for timing of follicle aspiration in unstimulated in vitro fertilization cycles

Purpose: To analyze the effects and potential benefits of a single midcycle dose of follicle-stimulating hormone (FSH) prior to human chorionic gonadotropin (hCG) administration during unstimulated in vitro fertilization (IVF) cycles. Methods: Twenty-five cycles from 20 patients receiving 150 IU of FSH 42-44 h and 10,000 IU of hCG 34-36 h prior to follicle aspiration were compared to 110 cycles triggered with hCG alone. Results: Serum E 2 levels were significantly lower on the day of hCG treatment in the FSH-treated group (266 vs. 297 pg/ml). On the day after hCG administration, serum E 2 was similar in both groups. Maximum follicular diameters the day of and the day after hCG treatment were similar as were the number of oocytes aspirated and embryos transferred, and clinical pregnancy rates in both groups. The number of cycles dropped due to premature luteinizing-hormone (LH) surge was 8% in the FSH group compared to 20% in the group treated with hCG alone. Conclusions : A midcycle FSH boost does not increase pregnancy success of unstimulated IVF cycles but does enhance the increase in serum E 2 levels after hCG, thereby potentially allowing earlier hCG administration while incurring decreased cycle cancellation rates due to premature LH surges.