Birth of FSH Protocol and the HCG Trigger

In IVF a follicle stimulating hormone (FSH) is used to promote growth of multiple follicles for a controlled ovarian hyperstimulation (COH). Common known brand name COH drugs include Gonal F and Follistim, which mimic natural FSH. Follicle growth is monitored, and as follicles approach maturity an injectable Human Chorionic Gonadotropin (HCG) is used as a “trigger” to control the timing of ovulation.