Which hormone stimulates milk production in the postpartum period?

• A. Oxytocin stimulates milk production.
• B. Prolactin stimulates milk production.
• C. Estrogen stimulates milk production.
• D. Progesterone stimulates milk production.

Answer: (B)

Milk production after birth is driven by prolactin, a hormone from the anterior pituitary. After delivery, the placenta is gone, and estrogen and progesterone levels fall, removing their inhibitory effect on the mammary glands. When the baby suckles, nerve signals to the brain reduce dopamine, leading to increased prolactin release and synthesis of milk in the alveolar cells. Oxytocin, while essential for the let‑down reflex to eject milk, does not stimulate its production. Estrogen and progesterone support breast tissue during pregnancy but don’t drive milk production postpartum. Thus, prolactin is the hormone that stimulates milk production in the postpartum period.