Abstract: Objective：To evaluate the role of short time incubation with in vitro maturation (IVM) medium containing 20% autologous serum in patients undergoing their first intracytoplasmic sperm injection (ICSI) cycles. Methods：Between January 2017 and July 2018, a total of 1 074 patients undergoing their first ICSI cycles were evaluated retrospectively. Patients were divided into the serum incubation group (n=819) and the non-serum incubation group (n=255), according to whether oocytes were in vitro cultured with the IVM medium containing 20% autologous serum or the routine fertilization medium for 2-4 h prior to sperm injection on the day of oocyte collection. General data, embryonic development and clinical outcomes of the two groups were compared. Results：There was no significant difference between the two groups in age, duration of infertility, body mass index, basal levels of FSH and LH (P＞0.05). The average number of oocytes collected, oocytes maturation rate, fertilization rate and blastocyst formation rate in the serum incubation group were slightly higher than those in non-IVM group, the high-quality blastocyst rate was slightly lower in the serum culture group, however there were no significant differences between the two groups (all P＞0.05). Fresh embryo transfer was performed in 47 cases in the serum culture group and 22 cases in the non-serum culture group. There was no significant difference in the age, basal level of FSH, endometrial thickness, number of embryos transferred, clinical pregnancy rate, cycle cancellation rate and implantation rate between the two groups for patients undergoing fresh embryo transfer (all P＞0.05). Interestingly, the abortion rate was significantly reduced (6.25% vs. 36.36%), and the live birth/continued pregnancy rate increased (93.75% vs. 63.64%) in the serum incubation group (both P＜0.05). Conclusions：The short time incubation of oocytes in the IVM medium containing 20% autologous serum for 2-4 h before ICSI can significantly reduce the abortion rate, in those patients undergoing ICSI treatment for the first time.

Key words: Sperm injections, intracytoplasmic, Embryo culture techniques, Autologous serum, In vitro maturation