Effects of M II stage oocytes zona pellucida birefringence on pregnancy outcome.

Objective: To explore the effects of different M II stage oocytes zona pellucida birefringence on pregnancy outcome.

Methods: A total of 46 couples with infertile which induced by single cause received in-vitro fertilization treatment were analyzed retrospectively, and randomly divided into the high zona birefringence (HZB)/HZB group, HZB/low zona birefringence (LZB) group and LZB/LZB group according to different oocytes zona pellucida birefringence. Intracytoplasmic sperm injection outcome was analyzed and compared.

Results: The proportion of HZB oocytes, implantation rate and the pregnancy rate were decreased in three groups (HZB/HZB group>HZB/LZB group>LZB/LZB group) (P<0.05). But there was no significantly different between the number of oocytes and fertilization rate of these groups (P>0.05). Logistic regression analysis showed that factors affect M II stage oocytes zona pellucida birefringence were age, basal FSH level and the LH level on the day of HCG injection. Age and FSH levels were negatively correlated with the single oocyte zona pellucida birefringence; While the LH level on the day of hCG injection was positively correlated with the single oocyte zona pellucida birefringence.

Conclusions: The primary influence factors on M II stage oocytes zona pellucida are age, basal FSH level and the LH level on the day of hCG injection. The birefringence value of zona pellucida can affect the pregnancy outcome.