What is the role of progesterone in pregnancy selection and maintenance?

Progesterone plays a crucial role in maintaining pregnancy, primarily by supporting the uterine lining. After conception, progesterone is secreted by the corpus luteum and later by the placenta. Its main function is to thicken and sustain the endometrium (the inner lining of the uterus), creating a suitable environment for the implanted embryo. This supportive role is vital; without appropriate progesterone levels, the uterine lining may not be adequately maintained, which can lead to a miscarriage.

In contrast, while blood pressure regulation, fetal brain development, and enhanced maternal circulation are important processes during pregnancy, they are not the direct roles of progesterone. Other hormones, such as estrogen, contribute to those aspects. Thus, the focus on progesterone's role in maintaining the uterine lining illustrates its essential function in ensuring the continuation of a healthy pregnancy.