Human chorionic gonadotrophin (hCG for short) is the unique pregnancy hormone that is produced by the cells of the placenta. hCG is needed to maintain the pregnancy and it also aids with fetal development. Experts theorize that this special hormone also plays a role in suppressing a pregnant woman’s immune system (so that her body doesn’t reject the developing baby as an “intruder.”)
Over-the-counter home pregnancy tests work by checking for the presence of hCG in a woman’s urine. If there’s any hCG in a woman’s body, she is indeed pregnant. Although hCG has been building up since conception, a urine pregnancy test won’t be able to pick up any hCG levels until 12 to 14 days after conception – around the time of a woman’s missed period.