In vitro fertilization without ovarian stimulation: a simplified protocol applied in 80 cycles.

Ovulation induction with various hormonal agents has become a standard component of in vitro fertilization (IVF) cycles to obtain multiple oocytes. Failure to anticipate the retrieval of more than two oocytes often results in cancellation of the cycle. In this study, we report our results in 80 unstimulated IVF cycles. Serum estradiol (E2) and pelvic ultra-sound monitoring were begun on day 9 of the cycle. Human chorionic gonadotropin (hCG) was administered when the E2 level exceeded 180 pg/mL and the dominant follicle was greater than 18 mm. Eighteen pregnancies were obtained (22.5%/cycle), and 14 (17.5%/cycle) are ongoing. We conclude that favorable results can be obtained from unstimulated IVF cycles, despite replacement of a single embryo.