Follicular maturation parameters associated with the failure of oocyte retrieval, fertilization, and cleavage in vitro

Follicular maturation parameters predictive of decreased success in human in vitro fertilization were evaluated in 104 gonadotropin-stimulated cycles. Falling estradiol (E 2 ) levels correlated with decreased fertilization (1.9 oocyte/cycle) and cleavage (1.4 oocyte/cycle), when compared with cycles with increasing E 2 (2.4 and 2.1 oocyte/cycle, respectively). Likewise, polyspermic fertilization was higher in the former group. Falling E 2 levels after human chorionic gonadotropin (hCG) administration correlated with similar trends. Delaying hCG (24 to 96 hours) relative to the last dose of gonadotropin did not affect the total number of oocytes fertilized per cycle. However, polyspermic fertilization and cancellation rates were higher. Leading follicles growing beyond 2.3cm (determined by ultrasound examination) were associated with decreased recovery, fertilization, and cleavage, and increased polyspermic fertilization. We conclude that ultrasonography and E 2 monitoring can predict decreased fertilization and cleavage and should also be monitored after hCG administration.