This hormone relaxes your uterus during pregnancy, keeping it from contracting too much and also relaxes the blood vessels, walls of the stomach and the bowels.

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

Answer: (A)

Progesterone keeps the uterus calm during pregnancy and prevents it from contracting too much. It also relaxes smooth muscle in other areas, including blood vessels and parts of the digestive tract, which helps maintain steady circulation and slower gut motility. This combination fits progesterone’s role in sustaining pregnancy: lowering uterine excitability and relaxing other smooth muscles to support a stable environment for the developing baby. Other hormones have different primary actions—estrogen promotes uterine growth and can increase readiness for contractions later, relaxin mainly loosens pelvic ligaments and cervix, and prostaglandins promote contractions—so they don’t match all the described effects as directly.