GNRH1 and ovarian hyperstimulation syndrome: Comparing OCP combined with the GnRH-ant protocol to the GnRH-a protocol, insufficient evidence was found to demonstrate differences in OHSS incidence (2 RCTs; OR 0.63, 95% CI 0.20 to 1.96, n = 290; I2 = 0%) or live birth or ongoing pregnancy rates.