OOCYTE MATURITY AS A PREDICTOR OF IVF OUTCOME

Abstract

Oocyte maturity after retrieval during IVF can vary significantly and is important in fertilization and development of embryos. Our purpose was to determine if low oocyte maturity from a retrieval cycle is a predictor of poor outcomes from IVF. Secondary objectives were; to identify factors predictive of low oocyte maturity, to assess oocyte maturity across cycles, and to determine if oocyte maturity is affected by the length of ovarian follicular stimulation or the total dose of gonadotropins used. Retrospective cohort study. A total of 1451 autologous IVF cycles from 1/2016- 7/2019 at our center were evaluated. Oocyte maturity was initially assessed upon retrieval (M1 + M2 oocytes/total oocytes). The final oocyte maturity assessment was made 5 hours post retrieval, prior to ICSI (oocytes inseminated at ICSI/total oocytes). As the maturity score at the time of retrieval was correlated with score at ICSI (Pearson’s r=.848, p ≤.001), we used maturity at retrieval as our measure of maturity, allowing inclusion of all cycles. Maturity designation as suboptimal vs. optimal was derived from previously established classifications (1). Statistical tests utilized included Pearson’s correlation, independent samples t-tests, and generalized estimating equations. There was no correlation between female age at retrieval and oocyte maturity (Pearson’s r= .131, p ≤.001). A diagnosis of polycystic ovarian syndrome (PCOS) was associated with a slightly reduced maturity (81.9% ± 14.6 vs. 85.5% ± 14.0, p=.002). There was no association with diminished ovarian reserve (defined as AFC< 10; DOR) and oocyte maturity (p=.172). Increasing oocyte maturity was associated with increased clinical pregnancy rates, age adjusted odds ratio (AOR) 2.5 (1.1-5.8). Oocyte maturity was not found to be associated with miscarriage rates. When cycle 1 was compared to cycle 2 in the same patient, there was a fair correlation between oocyte maturity scores (Pearson’s r=.339, p≤.001) with 44% of those classified as suboptimal maturity also classified as suboptimal maturity within their second cycle. In contrast, only 22% of cycles classified as optimal maturity in cycle 1 had suboptimal maturity if a second cycle was performed. There was no evidence of correlation between days of stimulation prior to the trigger shot or total gonadotropins used and maturity scores (Pearson’s r=0.43, p=0.149). There is no correlation between oocyte maturity and female age or diagnosis of DOR. The diagnosis of PCOS is associated with a slight but statistically significant reduced oocyte maturity at retrieval; however this is unlikely to be clinically significant given that these patients most often have an increased number of total oocytes retrieved. Low oocyte maturity was associated with decreased clinical pregnancy rates but did not impact miscarriage rates. Cycles complicated by low oocyte maturity can be repetitive, and maturity did not appear to correlate with the duration of ovarian stimulation or total gonadotropin dosage used.