So far, step-down protocols are described in anovulatory patients (WHO group II anovulation) for ovulation induction (23) and in ovarian stimulation for IVF/ICSI they are mainly used in high-responder patients to prevent ovarian hyperstimulation syndrome (OHSS), in patients with polycystic ovarian syndrome (PCOS) or to mimic the physiologic FSH course of a natural cycle in an ovarian stimulation cycle (24, 25). Here, BRD2 is linked to ovarian hyperstimulation syndrome.