Which hormone helps soften ligaments and widen the pelvic joints during birth?

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

Answer: (D)

Relaxin is the hormone that softens ligaments and widens the pelvic joints to prepare for birth. It’s produced during pregnancy and acts on connective tissue to increase the flexibility of ligaments, especially around the pelvis, allowing the pubic symphysis and sacroiliac joints to relax and widen the birth canal. This pelvic loosening helps create more space for the baby to pass through during labor. Other hormones have different roles—estrogen supports tissue elasticity and uterine changes, progesterone maintains pregnancy and relaxes the uterus, and prostaglandins promote cervical ripening and contractions—but the specific widening of pelvic joints and ligament loosening is primarily due to relaxin.