GNRH1 and ovarian hyperstimulation syndrome: Using low gonadotropin dose (75IU) in the start of COH, reducing the dose of trigger, changing the trigger time and freeze-all approach are commonly used in our center for those people with high risks of OHSS except GnRH antagonist protocol, and all of those strategies had been proved by researches (Nargund et al., 2007; Howles et al., 2010; Chen et al., 2016; Nelson, 2017; Shi et al., 2018; Zhang et al., 2018).