After ovulation, the corpus luteum is responsible for secreting progesterone, which is critical for maintaining the endometrial lining and creating a suitable environment for potential embryo implantation. Progesterone stabilizes the uterine lining, preventing menstruation during early pregnancy. Without sufficient progesterone from the corpus luteum, the endometrium breaks down, leading to menstruation. Thus, the corpus luteum’s primary role is hormonal support, particularly through progesterone production, until the placenta takes over later in pregnancy.

Reference: Gray's Anatomy, Susan Standring, 42nd Edition.