Factors inducing decreased oocyte maturation rate: a retrospective analysis of 20,939 ICSI cycles

Decreased oocyte maturation rate (OMR) is associated with worse clinical outcomes in IVF/ICSI cycles. The clinical features inducing decreased OMR remain unknown. The study is designed to explore the factors influencing the incidence of decreased OMR and its effects on clinical outcomes.

This is a retrospective case-control study analyzing data from 20,939 ICSI cycles in a reproductive center of university affiliated hospital from January 2015 to December 2017. Patients with a decreased OMR (< 30%) were characterized as Group A and those with an OMR ≥ 30% constituted Group B. Candidate factors of decreased OMR and clinical outcomes were compared between the two groups.

There were 1.3% cycles with an OMR < 30% and 22.16% of all oocytes retrieved (12.87 per cycle in average) were immature. Primary infertility, longer duration of infertility, larger BMI, more previous assisted reproductive times, less oocytes retrieved were risk factors for decreased OMR. Compared with long agonist protocol, patients received antagonist protocol for COH had a higher incidence of decreased OMR. The fertilization rate and subsequent embryo development of oocytes in Group A were worse than Group B. Implantation rate and clinical pregnancy rate were both lower in Group A than Group B.

Primary infertility, duration of infertility, BMI, previous assisted reproductive times, number of oocytes retrieved and COH protocol were found to be factors inducing decreased OMR. Patients with decreased OMR had worse clinical outcomes.