Prolactin levels during pregnancy?

Prolactin levels during pregnancy?

• A. Released from the anterior pituitary is inhibited during pregnancy by high estrogen, but stimulated after delivery by the placenta and suckling of the infant
• B. Prolactin levels are greatly increased during pregnancy and stay high postpartum
• C. Prolactin levels are decreased during pregnancy and remain low postpartum
• D. Prolactin levels are unaffected by pregnancy

Answer: (A)

Prolactin production by the anterior pituitary rises during pregnancy, priming the mammary glands for milk. But the high estrogen (and progesterone) environment of pregnancy blocks the actual secretion of milk, so lactation isn’t initiated yet even though prolactin is elevated. After delivery, the placenta is expelled, so those placental hormones fall dramatically, lifting the block on milk production. At the same time, nipple stimulation from the infant promotes prolactin release, supporting ongoing milk synthesis. In short, prolactin is inhibited during pregnancy by high estrogen, and postpartum signals—loss of placental hormones plus nipple stimulation—stimulate prolactin to drive lactation.

Prolactin production by the anterior pituitary rises during pregnancy, priming the mammary glands for milk. But the high estrogen (and progesterone) environment of pregnancy blocks the actual secretion of milk, so lactation isn’t initiated yet even though prolactin is elevated. After delivery, the placenta is expelled, so those placental hormones fall dramatically, lifting the block on milk production. At the same time, nipple stimulation from the infant promotes prolactin release, supporting ongoing milk synthesis. In short, prolactin is inhibited during pregnancy by high estrogen, and postpartum signals—loss of placental hormones plus nipple stimulation—stimulate prolactin to drive lactation.