During pregnancy, what does progesterone mainly maintain?

Progesterone plays a crucial role during pregnancy, primarily by maintaining the thickness of the uterine lining, also known as the endometrium. This hormone is secreted by the corpus luteum in the early stages of pregnancy and later by the placenta once it is formed. The thickened uterine lining is essential as it provides a suitable environment for the implantation of the fertilized egg and supports the developing embryo in the early stages of gestation.

By ensuring that the uterine lining is retained and not shed during menstruation, progesterone helps establish and sustain a healthy pregnancy. This hormonal support is vital for creating a protective and nourishing environment for the growing fetus throughout its development.

While progesterone does have various effects in the body, its primary and most critical function during pregnancy is to maintain the integrity and thickness of the uterine lining to support fetal development.