Pregnancies resulting from in vitro matured oocytes collected from women with regular menstrual cycle

Purpose: To demonstrate that human immature oocytes retrieved from women wi th regular menstrual cycles can undergo maturation and fertilization, and t hat the resulting embryos can establish pregnancies. Methods: Immature oocytes (n = 568) weve retrieved from women with regular menstrual cycle. The intact immature oocytes (n = 506) were allowed to matu re in YS medium supplemented with 70% human follicular fluid (hFF); the mat ured oocytes were fertilized with husband sperm. Two pronuclei oocytes were cocultured with cumulus cells in YS medium supplemented with 10% hFF until 2 or 3 days after insemination. The cleaved embryos were transferred in ut eri. Results: Follicles were aspirated on Day 9.2 +/- 5.3 of 63 natural cycles f rom 51 patients (mean age = 34.8 +/- 4.0 year). The average number of retri eved immature oocytes was 9.0. The maturation rate was 74.3% (376/506). The two PN and cleavage rates were 72.6% (273/376) and 89.0% (243/273), respec tively, Embryo transfer was achieved in 51 cycles and clinical pregnancy ra te was 17.6% (9/51). Conclusions The results suggest that in vitro matured oocytes can undergo f ertilization and the resulting embryos may successfully lead to pregnancies . However, further research is needed to improve IVM technique to achieve s uccess rate comparable to gonadotrophin stimulated cycles.