Fertilization outcome, embryo development and birth after unstimulated IVM

A common observation in oocyte in vitro maturation (IVM) cycles is poor embryo quality. However, no study was dedicated to assess zygote and early cleavage embryo quality in IVM cycles. The objective of this study is to analyze fertilization outcome, embryo development and the resulting pregnancy and births in unstimulated IVM cycles.

IVM oocytes were collected 36 h post hCG and matured in vitro for 28-30 h. All oocytes were inseminated by ICSI. Resulting zygotes and embryos were assessed on day-1, 2 and 3, when transfers were made.

The overall oocyte maturation and fertilization rates were 63% and 62%, respectively. Abnormal fertilization rate was 27%. [corrected] Ninety five and 14.6% of the 2Pn zygotes reached the 2-cell and 8-cell stage at day-2 and day-3, respectively. Embryo quality assessment on day-3 at transfer revealed that only 9% of the embryos were of very good quality. Most embryos showed developmental delay. An average of 3.29 embryos were transferred per patient resulting in implantation and clinical gestation rates of 16% and 32%, respectively. Overall 14 healthy babies were born and there is one ongoing pregnancy.

Results show a significant rate of abnormal fertilization and poor embryo quality after IVM, which is reflected in a higher than average number of embryos being transferred. However, pregnancy, implantation and birth rates are reasonably high and allow us to consider IVM a valuable approach for the treatment of infertility in PCO or PCOS patients.