Which hormone is primarily responsible for maintaining pregnancy?

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

Answer: (B)

Progesterone is the hormone primarily responsible for maintaining pregnancy. It plays a critical role in preparing the endometrium (the lining of the uterus) to receive and sustain a fertilized egg. After conception, progesterone is produced in high amounts by the corpus luteum and later by the placenta, which helps maintain the uterine lining, preventing its breakdown and supporting the growing embryo.

Progesterone also limits uterine contractions and supports the developing fetus by modulating the immune response, ensuring that the mother's body does not reject the embryo. Thus, its production is essential for the continuation of a healthy pregnancy.

Estrogen does contribute to pregnancy by promoting uterine growth and enhancing blood flow to the uterus, but it is not the hormone that primarily maintains the pregnancy. Testosterone is not involved in the maintenance of pregnancy; it is primarily a male hormone with functions related to male reproductive processes. Relaxin, produced during pregnancy, facilitates childbirth by relaxing the ligaments in the pelvis and softening the cervix, but its role is supportive and not primary in maintaining pregnancy.