Which of the following hormones is crucial for the maintenance of pregnancy?

Progesterone plays a vital role in maintaining pregnancy by preparing the endometrium (the lining of the uterus) for the implantation of a fertilized egg and supporting the early stages of pregnancy. After conception, progesterone production increases, which helps to maintain the uterine lining and prevent its shedding, thus creating a suitable environment for the developing embryo. Additionally, progesterone inhibits uterine contractions, which is essential to prevent the premature onset of labor.

In contrast, other hormones listed have different functions. Oxytocin is primarily involved in stimulating labor and milk ejection during breastfeeding but does not play a significant role in the initial maintenance of pregnancy. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are key players in regulating the menstrual cycle and ovulation but do not have a direct role in sustaining pregnancy after fertilization occurs. Overall, progesterone is essential for the successful continuation of pregnancy.