Human chorionic gonadotropin (HCG, Novarel, Ovidrel, Pregnyl) is a polypeptide hormone produced by the human placenta. It has been used by some avian veterinarians to help stop chronic egg-laying in poultry. HCG has demonstrated to be a safer alternative with significantly fewer side effects when compared to other hormone therapy drugs. However, its effects at stopping ovulation (egg laying) have not been consistently effective. How HCG Works: The use of this hormone is linked to it s primarily luteinizing hormone (LH) alpha sub-unit activity, which results in an increase in progesterone (and some increase of estrogen and testosterone) in female birds. The theory behind it s effectiveness is that high levels of progesterone supplied to the developing follicles causes atresia and stops the development of future developing follicles.