[An exploration of contributing factors to the oocyte utility rate of high responders in an in vitro fertilization cycle]

Objective: To figure out the clinical factors contributing to the oocytes utility rate (OUR) of high responders in in vitro fertilization (IVF)-embryo transfer treatment. Methods: OUR was defined by the number of usable embryos for transfer and (or) cryopreservation divided by the number of oocytes retrieved in a freeze-all cycle. The cycles with ≥15 eggs were included from January 2013 to December 2019. Those with OUR at the top 10% (Group A) and the bottom 10% (Group B) were picked and compared for patients' characteristics, parameters relating to ovary stimulation and pregnant outcomes. Multifactorial logistic regression was applied to reveal the risk factors affecting OUR in them. Results: A total of 43 patients were included in Group A (OUR: 77.4%, 601/776) and 47 for Group B (OUR: 11.9%, 104/874). Previous IVF/intracytoplasmic sperm injection (ICSI; OR=0.10, 95%CI: 0.01-0.81) and endometriosis (OR=0.16, 95%CI: 0.03-0.84) were negative factors for OUR (P<0.05); dual suppression protocol (OR=3.74, 95%CI: 1.06-26.86) and longer days of stimulation (OR=3.24, 95%CI: 1.25-8.42) were protective factors in terms of ovarian stimulation (P<0.05), on contrary to that, any decline of estradiol during the stimulation led to poorer OUR (OR=0.16, 95%CI: 0.04-0.64). Although two groups had similar quantities of eggs and metaphase of meiosis Ⅱ (MⅡ) oocytes, distinguished cumulative clinical pregnancy rate and cumulative live birth rate were seen in Group A and group B respectively [95.3% (41/43) vs 40.4% (19/47) and 90.7% (39/43) vs 31.9% (15/47), all P<0.01]. Conclusions: High responders with attempted IVF/ICSI and endometriosis should be considered as risk factors for OUR. Over ovarian stimulation, dual suppression and a slightly longer stimulating duration could be tried; besides, estradiol decline should be prevented for a better OUR.