Beta-Human Chorionic Gonadotropin is a glycoprotein hormone produced in pregnancy, regardless of the site of implantation, by the developing embryo soon after conception and later by the syncytiotrophoblast (part of the placenta). During the early weeks of pregnancy, hCG is important in maintaining the function of the corpus luteum, and thereby maintains progesterone production. It also affects the immune tolerance of the pregnancy. This test is used to confirm or rule out pregnancy. It is also ordered to help diagnose an ectopic pregnancy, monitor a pregnancy that may be failing, or to monitor a woman after miscarriage. Multiple pregnancies like twins, triplets, or multiples are also identified by high hCG levels. b-hCG can be detected at one week after conception. Production increases steadily during the first trimester (8-10 weeks) 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. Therefore, an INCREASE of b-hCG levels are associated with pregnancy, and as a rule, it should double every 36 to 48 hours. A DRAMATIC DECREASE in the levels may indicate a miscarriage. A level that STAYS THE SAME, OR FALLS WELL BELOW THE NORMAL RANGE may indicate an ectopic pregnancy.