The ovarian sensitivity index (OSI) is predictive of live birth chances after IVF in infertile patients with relative poor prognosis

Abstract

The ovarian sensitivity index (OSI), defined as the amounts of gonadotropins utilized per oocyte retrieved, was recently introduced to account for different gonadotropin requirements among high, normal and poor responders and demonstrated superiority to oocyte numbers in predicting pregnancy potential in younger patients undergoing FSH stimulation 1. We here evaluated whether the OSI is also superior to age and oocyte yields in predicting embryo quality, pregnancy potential and live births in an older, more unfavourable patient population undergoing combined FSH/hMG stimulation for IVF. Retrospective cohort study in academically affiliated private fertility center. We retrospectively investigated the relationship between baseline characteristics, total gonadotropin dosages, OSIs, oocyte yields, embryo development, pregnancy rates and live births in 1934 fresh IVF cycles in 1282 women. According to ovarian function, patients received a daily gonadotropin dosage of up to 600IU of gonadotropins in 3:1 FSH/hMG distribution. Cancelled cycles and those without oocytes at retrieval were excluded. Oocyte numbers, total gonadotropin dosages and OSIs were not normally distributed and, therefore, log converted. OSIs were grouped into tertiles to compare low, medium and high gonadotropin requirement per oocyte retrieved. Patients presented at 39.3±5.3 years, with AMH levels of 1.3±1.7ng/mL, received a total gonadotropin dosage of 5357±2411IU and produced 7.6±6.5 oocytes. Pregnancy and live birth rates were 22.0% and 16.5%, respectively. Women in with low, medium and high OSIs were 36.4±5.6, 40.3±4.4 and 41.1±4.5 years old (P=0.001). After controlling for age and egg numbers, patients with lower OSIs (less gonadotropin requirement per oocyte retrieved) produced significantly more high-quality embryos than patients with medium and high OSIs (5.1±4.3 vs. 2.3±1.8 vs. 1.0±1.01, P=0.001) and also demonstrated higher pregnancy (30.9% vs. 20.4% vs.12.8%) and live birth rates (24.7% vs. 14.3% vs. 8.8%) than their counterparts (P=0.005 and P=0.02, respectively). This study demonstrates that the ovarian sensitivity index is predictive of embryo quality, pregnancy potential and live birth in infertile patients after FSH/hMG stimulation for IVF. Patients’ gonadotropin response, reflected in the OSI, may thus aid in counselling patients about their pregnancy potential in the course of IVF.