How does the placenta help maintain pregnancy through hormone production?

The placenta maintains pregnancy by acting as an endocrine organ that secretes essential hormones to support fetal development.1

In early pregnancy, the placenta produces human chorionic gonadotropin (HCG) and human placental lactogen. HCG is critical because it stimulates the corpus luteum to continue secreting progesterone, which is necessary to maintain the uterine environment.12

As pregnancy progresses—typically after two months in humans—the placenta begins to manufacture its own estrogen and progestin. By producing these hormones directly, the placenta eventually renders the corpus luteum unnecessary for the continuation of the pregnancy. This process involves an integrated endocrine complex where the placenta works in conjunction with the fetus, which provides precursor compounds like dehydroepiandrosterone for estrogen synthesis. Through these hormonal pathways, the placenta ensures the uterus remains receptive and stable for the developing fetus.13