The different impact of stimulation duration on oocyte maturation and pregnancy outcome in fresh cycles with GnRH antagonist protocol in poor responders and normal responders.

To study the impact of stimulation duration on intracytoplasmic sperm injection (ICSI) - embryo transfer (ET) outcome in poor and normal responders during controlled ovarian stimulation using gonadotropin-releasing hormone (GnRH) antagonist protocol. This is a retrospective cohort study. There were 1481 women undergoing ICSI-ET cycles. Women with ovum pick-up number ≤3 were defined as poor responders (n = 235), and those with a number ≥4 were normal responders (n = 1246). The mean stimulation duration was shorter in poor responders with pregnancy group as compared with normal responders with pregnancy group (7.8 ± 2.2 vs. 9.2 ± 1.6 days, p < 0.01). Poor responders with a shortest stimulation duration (≤6 days) appeared a higher live birth rate (≤6 days: 33.3%, 7-8 days: 20.0%, 9-10 days: 15.9%, and ≥11 days: 11.1%, p = 0.18). Normal responders with a shortest stimulation duration (≤6 days) appeared a lowest live birth rate (≤6 days: 28.6%, 7-8 days: 35.8%, 9-10 days: 33.6%, and ≥11 days: 29.3%, p = 0.61). Oocyte maturation rate was significantly lower at stimulation durations ≤6 days group (≤6 days: 67%, 7-8 days: 80%, 9-10 days: 85%, and ≥11 days: 87%, p = 0.02) in normal responders. In ICSI-ET cycles, stimulation duration appears to have different impact on oocyte maturation, clinical pregnancy rates and live birth rates in both poor and normal responders.