Cumulative live birth rates according to the number of oocytes retrieved after the first ovarian stimulation for in vitro fertilization/intracytoplasmic sperm injection: a multicenter multinational analysis including ∼15,000 women

Abstract

To evaluate the association between the number of oocytes retrieved and cumulative live birth rates. Retrospective multicenter analysis using individual patient data. Tertiary referral hospitals. In total, 14,469 patients were analyzed. The study included the first cycle of patients stimulated for IVF/intracytoplasmic sperm injection (ICSI) from 2009 to 2014. All patients included in the analysis had either delivered a baby or had used all their embryos after their first stimulated cycle. All patients had vitrification as cryopreservation method. All women were followed up for at least 2years. Ovarian stimulation with GnRH antagonist protocol for IVF/ICSI. The primary outcome was the cumulative live birth rate defined as the delivery of at least one live-born infant (>24weeks of gestation) in the fresh or in the subsequent frozen-thawed cycles in relation to the number of oocytes retrieved. Only the first delivery was considered in the analysis. The secondary outcome was live birth after the fresh IVF/ICSI cycle only. Cumulative live birth rates steadily increased with the number of oocytes, reaching 70% when ≥25 oocytes were retrieved. Interestingly, no plateau in cumulative live birth rates was observed, but a moderate increase of 5.1% on average was detected beyond 27 oocytes. Regarding the fresh cycle outcome, live birth probability increased up to seven oocytes retrieved and remained relatively unchanged (increase or decrease of ≤5%) between seven and 20 oocytes retrieved. However, a drop in fresh live birth rates was identified thereafter, which could be attributed to the progressive increase in "freeze-all" cycle rate with the number of oocytes retrieved, exceeding 20% in patients with >20 oocytes retrieved. This is the largest multicenter study evaluating for the first time the impact of ovarian response on cumulative live birth rate. The significant progressive increase of cumulative live birth rate with the number of oocytes in our study suggests that ovarian stimulation may not have a detrimental effect on oocyte/embryo quality in good-prognosis women less than 40year old. Nevertheless, although very high ovarian response may further increase cumulative live birth rates, ovarian stimulation should be rational and avoid extreme response in terms of oocytes retrieved to preserve patients' convenience and safety and avoid ovarian hyperstimulation syndrome or other iatrogenic complications.