A nurse is teaching a prenatal patient about pregnancy hormones, Which hormone is primarily responsible for maintaining the uterine lining and preventing contractions during pregnancy?

A. Estrogen is incorrect because, while estrogen promotes uterine growth, blood flow, and development of the mammary glands, it does not primarily maintain the uterine lining or prevent contractions. Estrogen actually increases toward the end of pregnancy and can help sensitize the uterus to oxytocin, promoting labor. B. Progesterone is correct because it maintains the endometrial lining, supporting implantation and early fetal development, and inhibits uterine contractions throughout pregnancy. By relaxing smooth muscle in the uterus, progesterone helps prevent premature labor and miscarriage. Its levels remain high during most of pregnancy and decrease near term to allow labor to begin. C. Human Chorionic Gonadotropin (hCG) is incorrect because hCG’s primary role is to signal the corpus luteum to continue producing progesterone during early pregnancy. While essential in the first trimester, it does not directly maintain the uterine lining or prevent contractions throughout pregnancy. D. Relaxin is incorrect because relaxin primarily relaxes the ligaments of the pelvis and softens the cervix to prepare for labor. It does not maintain the endometrium or inhibit uterine contractions.