HCG (Human Chorionic Gonadotropin) is a hormone produced by cells that form the placenta after an embryo implants in the uterine lining. It’s the hormone detected by pregnancy tests.
What hCG Does:
The primary role of hCG is to signal the corpus luteum to continue producing progesterone during early pregnancy. Without hCG, the corpus luteum would degenerate, progesterone would drop, and the uterine lining would shed, ending the pregnancy. HCG maintains progesterone production until the placenta develops enough to take over hormone production, usually around 8-10 weeks of pregnancy.
HCG Levels in Pregnancy:
HCG can be detected in blood about 11 days after conception and in urine about 12-14 days after conception (around the time of a missed period). Levels rise rapidly in early pregnancy, typically doubling every 48-72 hours during the first few weeks. They peak around 8-11 weeks of pregnancy, then gradually decline and level off for the remainder of pregnancy.
Why It’s Measured:
Home pregnancy tests detect hCG in urine. Blood tests can measure exact hCG levels to confirm pregnancy, estimate how far along a pregnancy is, or identify potential problems (levels that don’t rise appropriately may indicate miscarriage or ectopic pregnancy, while unusually high levels might indicate twins or other conditions).
