We categorized 18,272 cycles into three groups by the number of oocytes retrieved (1–8, 9–17, and ≥ 18) during IVF with the GnRH-a prolonged protocol at the Reproductive Medical Center of Jiangxi Maternal and Child Health Hospital from January 2014 to December 2018 (excluding oocyte donation cycles), analyzing the associations among oocyte number and live birth rates (LBRs) or cumulative LBRs (CLBRs), as well as the rate of moderate-to-severe ovarian hyperstimulation syndrome (OHSS). Here, GNRH1 is linked to ovarian hyperstimulation syndrome.