During an vitro fertilization (IVF) protocol, your doctor may use leuprolide (Lupron) injection as part of an ovarian stimulation regimen. Leuprolide is a gonadotrophin-releasing hormone (GnRH) agonist. It reduces the amount of hormone that stimulates ovulation. This helps to control your ovulatory cycle and prevent premature ovulation, so that your doctor can have predictable access to your eggs for IVF. The brand name Lupron is no longer available in the U.S., but generic options are available.