But in fact, either slow ovarian response or hyperstimulation would easily occur during ovarian stimulation due to inappropriate ovarian stimulation by exogenous FSH, and the heterogeneity of PCOS patients might enhance the probability of uncertain follicle development, so the flexible protocol seems to be more beneficial for PCOS women in clinical outcome, which is also recommended for PCOS women and poor ovarian responders by the clinical consensus on GnRH antagonist protocol in China [13]. This evidence concerns the gene GNRH1 and polycystic ovary syndrome.