Which hormone helps prepare and maintain the endometrium?

• A. Estrogen
• B. Progesterone
• C. Luteinizing hormone
• D. Follicle-stimulating hormone

Answer: (B)

This question focuses on how hormones regulate the uterine lining across the menstrual cycle. Estrogen drives the thickening of the endometrium during the proliferative phase, but the hormone that prepares and maintains it after ovulation is progesterone. Secreted by the corpus luteum, progesterone transforms the proliferative lining into a secretory one, promoting glandular development, secretions, and increased vascularity to support potential implantation. If fertilization doesn’t occur, progesterone levels fall and the endometrium sheds. If pregnancy occurs, the embryo’s hCG keeps the corpus luteum producing progesterone to sustain the endometrium in early pregnancy. LH and FSH regulate ovarian function and ovulation, but they don’t directly maintain the endometrium.