Objective: To compare the effects of in vivo and in vitro maturation of human oocytes. Design: Women (n = 60) undergoing follicular stimulation for in vitro fertilization, using long-course analog therapy to suppress endogenous luteinizing hormone (LH), were randomly allocated to a short (34 hour) or long (39 hour) delay between human chorionic gonadotropin (hCG) administration and oocyte retrieval. Each patient's oocytes were divided into two groups that were either inseminated immediately or after 5 hours. Results: The incidence of polyspermic fertilization was highest in oocytes inseminated immediately after a short hCG/oocyte retrieval interval (17/100) and was significantly (P < 0.05) reduced by preincubation and/or a long hCG/oocyte retrieval interval. Fertilization rates were higher with 39 hours than with 34 hours in vivo maturation (84.2% versus 76.8%; P < 0.05). The incidence of delayed fertilization was reduced by extending the hCG/oocyte retrieval interval (short, 12.9%; long, 3.9%; P < 0.001). Conclusions: Extension of the in vivo maturation time increased fertilization rates and eliminated the requirement for preinsemination incubation, allowing simplification of laboratory procedures.
Jamieson, M. E., Fleming, R., Kader, S., Ross, K. S., Yates, R. W. S., & Coutts, J. R. T. (1991). In vivo and in vitro maturation of human oocytes: Effects on embryo development and polyspermic fertilization. Fertility and Sterility, 56(1), 93–97. https://doi.org/10.1016/s0015-0282(16)54424-0