What is the role of human chorionic gonadotropin (hCG) during pregnancy?

Human chorionic gonadotropin (hCG) plays a pivotal role early in pregnancy, primarily by helping to maintain the corpus luteum. After the ovary releases an egg, the corpus luteum forms and is responsible for producing progesterone, which is crucial for establishing and maintaining the uterine lining for embryo implantation.

When conception occurs, hCG is produced by the developing embryo and later by the placenta. The presence of hCG signals the corpus luteum to continue its production of progesterone beyond its normal lifespan, which is essential to prevent the menstrual cycle from continuing and to support early pregnancy. This increased progesterone secretion helps maintain the uterine lining, providing a stable environment for the growing fetus.

In contrast, while fetal development is vital during pregnancy, hCG does not directly promote fetal growth; this task is primarily managed by other hormones. Additionally, while hCG does have some indirect effects on maternal physiology, it is not primarily responsible for stimulating uterine contractions or increasing maternal blood volume—these processes are regulated by different hormones and mechanisms during pregnancy.