Human chorionic gonadotropin （hCG） is a peptide hormoneproduced in pregnancy， that is made by the embryosoon after conceptionand later by the syncytiotrophoblast（part of the placenta）. Its role is to prevent the disintegration of the corpus luteumof the ovaryand thereby maintain progesteroneproduction that is critical for a pregnancyin humans. hCG may have additional functions， for instance it is thought that it affects the immune tolerance of the pregnancy. Early pregnancy testinggenerally is based on the detection or measurement of hCG.
