Which factor most commonly contributes to delayed involution?

• A. Retained products of conception.
• B. Active mobilization and early ambulation.
• C. Adequate nutrition.
• D. Regular follow-up visits.

Answer: (A)

Involution is the uterus returning to its pre-pregnant size after birth, which depends on complete placental separation and strong uterine contractions to compress blood vessels. Retained products of conception—placental tissue left inside the uterus after delivery—are the most common reason involution is delayed. When tissue remains, the uterus cannot contract effectively, so it stays larger and boggy, with prolonged lochia and a higher risk of postpartum hemorrhage or infection. The other factors listed—early mobilization, adequate nutrition, and routine follow-up—support recovery but don’t cause the uterus to fail to involute. If retained tissue is present, evaluation and removal (often with dilation and curettage) are typically needed.