Effect of Stimulation Duration on Oocyte Maturation in Patients With Normal Ovarian Reserve Undergoing a Gonadotropin-Releasing Hormone Agonist Protocol: A Propensity Score Matched Study

Background: This study aimed to investigate the effect of gonadotropin (Gn) stimulation duration on the oocyte maturation rate in patients with normal ovarian reserve undergoing a gonadotropin-releasing hormone agonist (GnRHa) protocol. Methods: Data were retrospectively collected from patients with normal ovarian reserve who underwent a GnRHa protocol at the Reproductive Center of Changzhou Maternity and Child Health Care Hospital between January 1, 2017, and December 31, 2022. A total of 2840 cycles were included and categorized into three groups based on stimulation duration: <7 days, 7–10 days, and >10 days. Results: The results showed that patients with a Gn stimulation duration of ≥7 days exhibited significantly higher metaphase II (MII) oocyte rates, clinical pregnancy rates, and live birth rates compared with those with a stimulation duration of <7 days. Correlation and linear regression analyses identified Gn stimulation duration as an independent predictor of the MII oocyte rate. Curve fitting analysis demonstrated that when the stimulation duration was <7 days, the MII oocyte rate increased with longer Gn stimulation. Conclusions: For patients with normal ovarian reserve undergoing a GnRHa regimen, the optimal Gn stimulation duration is at least 7 days. Gn stimulation duration was positively correlated with the MII oocyte rate and independently predicted oocyte maturation. These findings provide valuable evidence for optimizing clinical management in this patient population.