Prevalence in vivo maturation of human oocytes for conventional IVF-ET

Optimal interval between hCG administration and oocyte retreaval in IVF-ET was assessed. Subjects included women (n=60) undergoing follicular stimulation for IVF-ET, with using long- or short-courses of GnRH agonist regimen to suppress endogenous LH. They were submitted at random to a short (34 hours) or a long (39 hours) delay between hCG administration and oocyte retrieval. Each patient's oocytes were inseminated immediately in a long delay or 5 hours after in vitro maturation in a short delay; no unexpected ovulation occurred before oocyte retreaval throughout the study. Insemination immediately after a short hCG/oocyte retrieval interval (5.41%) protected the polyspermic fertilization, compared to oocytes preincubated before insemination (7.24%). A short hGG/oocyte retrieval interval significantly reduced this polyspermic fertilization incidence (p<0.05). Fertilization rates were higher with 39 hr (82.2%) than with 34 hr (75.2%) in vivo maturation (P < 0.05). Extending the hCG/oocyte retrieval interval (3.9%) reduced the incidence of delayed fertilization (12.9%). Pregnancy rates per ET were higher with 3 9 hr (30.2%) than with 34 hr (23.1%) in vivo maturation (P < 0.05). These findings led us to the conception that prolonged oocyte maturation interval up to 39 hours resulted in prevalent fertilization rates, and improved the required interval for presemination. These findings may permit the simple, safe and time-spared laboratory procedures.