Zona pellucida thickness and clinical pregnancy outcome following in vitro fertilization

To investigate possible correlations of ZPT or ZPTV with clinical outcome following in vitro fertilization.

Two hundred forty-six embryos were selected for transfer on day 3 with clear image record from 81 IVF-ET cycles. The laser system measurement software was used to measure the ZTP value of each embryo and the ZPTV was computed. Statistical analysis was done using the ANOVA or Chi-square test.

Both ZPT and ZPTV declined with women's age. The mean ZPTV of embryos from patients between 30 and 34 years old was significantly higher than that from patients older than 35 (P<0.001). The ZPTV in pregnancy group was significantly higher than that in nonpregnancy group (P<0.005). The clinical pregnancy rate in the group with ZPTV more than 20% was significantly higher than that in the group with ZPTV less than 20% (P<0.05). The ZPTV of high grade embryos was significantly higher than that of low grade embryos (P<0.001).

ZPTV rather than ZPT is an effective parameter to evaluate the embryo quality. Increasing the ZPTV may enhance embryo implantation potential.