Embryological Characteristics and Clinical Outcomes of Oocytes with Heterogeneous Zona Pellucida During Assisted Reproduction Treatment: A Retrospective Study

BACKGROUND: The condition of the zona pellucida can be used to predict human oocyte quality. This study investigated the embryological characteristics and clinical outcomes of oocytes with heterogeneous zona pellucida (HZP) during in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). MATERIAL/METHODS: This was a retrospective study of IVF and ICSI cycles undertaken at The First Affiliated Hospital of Wenzhou Medical University between June 2006 and March 2016. Cycles involving oocytes with HZP (HZP group) were compared with those involving non-HZP oocytes retrieved on the same day (non-HZP group). Embryological characteristics and clinical outcomes were compared. RESULTS: There were 29 IVF and 46 ICSI cycles in the HZP group, and 521 IVF and 206 ICSI cycles in the non-HZP group. In ICSI cycles, the rates of MII oocyte and high-quality embryo were lower in the HZP group (p<0.05 vs. non-HZP). In IVF cycles, the MII oocyte (p<0.001), normal fertilization (p<0.001), and cleavage (p<0.001) rates were lower, while the abandoned transfer rate (p<0.001) was higher in the HZP group compared with the non-HZP group. The positive human chorionic gonadotropin (HCG), implantation, pregnancy, and miscarriage rates were similar between groups. Multivariate analysis revealed that the woman’s age (OR=0.916 95% CI 0.873–0.962; p<0.001) and the number of D3 high-quality embryos (OR=1.120 95% CI 1.004–1.249; p=0.043) were associated with pregnancy in IVF cycles, but no significant factors were found in ICSI cycles. CONCLUSIONS: ICSI may help increase the number of viable embryos in cycles with oocytes showing HZP. However, both IVF and ICSI cycles can achieve pregnancy.