Which hormone is secreted by the ovaries and prepares the uterus for pregnancy?

• A. Progesterone
• B. Estrogen
• C. Testosterone
• D. Sperm

Answer: (A)

Progesterone from the ovaries plays the key role in preparing the uterine lining for pregnancy. After ovulation, the corpus luteum releases progesterone, which thickens the endometrium and shifts it into a secretory state rich in nutrients, making it receptive to a fertilized egg. It also helps maintain the lining and reduces uterine contractions to protect early pregnancy. If there is no fertilized egg, progesterone levels fall, and the lining is shed during menstruation. Estrogen helps build the lining earlier in the cycle, but the essential preparation for implantation is driven by progesterone. Testosterone is not the primary ovarian hormone for this process, and sperm is not a hormone.