HCG trigger (Pregnyl)

This hormone is similar to the luteinizing hormone or LH. Its job is to prepare the follicle for rupture. The triggers starts an important phase of division of the egg needed for it to mature. HCG is typically given 35 or 36 hours before the proposed time of egg collection. Each follicle larger than 17 m or 18 mm in size are good enough to give an egg. HCG traditionally came from human placenta (hence its name Human Chorionic gonadotrophin). This the very hormone we check in your pregnancy test. If there are excessive follicles then the trigger injection can cause the precipitation of ovarian hyper stimulation syndrome. This in turn gets worse if the woman gets pregnant wherein the implanted embryo starts secreting its own hCG. Some clinics use hCG to support the corpus luteum which produces progesterone needed for the embryo to survive.