What is the role of Prolactin produced by the anterior pituitary?

Prolactin is a hormone produced by the anterior pituitary gland primarily responsible for stimulating the production of breast milk, also known as lactation, in postpartum women. After childbirth, prolactin levels rise significantly, which promotes the development of the mammary glands and the synthesis of milk. This role is crucial for breastfeeding, as it encourages the mother to produce milk necessary for the nourishment of her infant.

Additionally, prolactin plays a role in reproductive health and can inhibit ovulation while a woman is breastfeeding, contributing to natural spacing of pregnancies. This hormone’s action is facilitated by suckling, which prompts the anterior pituitary to release more prolactin in response to the infant's feeding cues.

In contrast, the other options do not accurately describe the primary role of prolactin. Thyroid hormone synthesis is stimulated by thyroid-stimulating hormone (TSH), metabolism regulation is mainly under the influence of hormones like insulin, glucagon, and thyroid hormones, and muscle growth is influenced by hormones like testosterone and growth hormone. Therefore, the choice that identifies prolactin's role in milk production highlights its significance in the reproductive and lactation processes.