HCG, Chorionic gonadotropin is a hormone found in the female body during the early months of pregnancy (it is produced in the placenta). It is in fact the pregnancy indicator looked at by the over the counter pregnancy test kits, as due to its origin it is not found in the body at any other time. Blood levels of this hormone will become noticeable as early as seven days after ovulation. The level will rise evenly, reaching a peak at approximately two to three months into gestation. After this point, the hormone level will drop gradually until the point of birth.