Human chorionic gonadotropin (hCG) is a hormone produced by the placenta of a pregnant woman. Early in pregnancy, the level of hCG increases in the blood and is eliminated in the urine. A pregnancy test detects hCG in the blood or urine and confirms or rules out pregnancy.
During the early weeks of pregnancy, hCG is important in maintaining function of the corpus luteum. Production of hCG increases steadily during the first trimester (8-10 weeks) of a normal pregnancy, peaking around the 10th week after the last menstrual cycle. Levels then fall slowly during the remainder of the pregnancy. hCG is no longer detectable within a few weeks after delivery.