During pregnancy, progesterone is primarily produced by which structure later in gestation?

The placenta is the primary structure responsible for the production of progesterone later in gestation. During the early stages of pregnancy, the corpus luteum, which forms after ovulation, produces progesterone to maintain the uterine lining and support the early development of the embryo. However, as pregnancy progresses, particularly around the end of the first trimester, the placenta takes over this role.

This transition is crucial because the placenta not only produces progesterone but also other hormones necessary for sustaining the pregnancy, ensuring the uterine environment is optimal for fetal growth, and preventing uterine contractions that could lead to premature birth. The placental production of progesterone continues throughout pregnancy, highlighting its essential role in ensuring the maintenance and viability of the pregnancy until delivery.

In contrast, while the ovaries and adrenal glands do have roles in hormone production, they are not the primary source of progesterone during the later stages of pregnancy. The corpus luteum is important in the early stages, but its function diminishes as the placenta becomes the dominant hormonal organ.