Which hormone is produced by the placenta to maintain pregnancy?

Progesterone is the hormone primarily produced by the placenta to maintain pregnancy. Its main role is to prepare the uterine lining for the implantation of the fertilized egg and to help sustain the pregnancy once implantation has occurred. Progesterone works by inhibiting uterine contractions, thus preventing premature labor. It also promotes the growth of blood vessels in the uterine lining and supports the developing fetus by creating a suitable environment for growth.

While estrogen also plays a crucial role in pregnancy by promoting uterine growth and stimulating breast tissue development, its primary function is often seen in conjunction with progesterone. Oxytocin is mainly involved in labor and delivery, triggering uterine contractions during childbirth. Lactogen is produced to ensure that the baby has adequate nutrition, but it does not play a primary role in maintaining pregnancy. Therefore, progesterone is the key hormone that directly supports the continuation and maintenance of a healthy pregnancy.