Which hormone is primarily responsible for stimulating milk production in the breasts?

Prolactin is the hormone that plays a critical role in stimulating milk production in the breasts. It is produced by the anterior pituitary gland and is essential for lactation during and after pregnancy. The presence of prolactin leads to the development of mammary glands and the production of milk, ensuring that nursing mothers can feed their infants.

During pregnancy, elevated levels of prolactin prepare the breasts for milk production, and after childbirth, the release of this hormone is further stimulated by suckling, reinforcing its importance in breastfeeding. This unique function highlights how prolactin is specifically designed to support maternal-infant bonding through milk provision.

Other hormones, such as ghrelin and leptin, are involved in appetite regulation and energy homeostasis rather than directly in milk production. Luteinizing hormone primarily regulates functions in the reproductive system, particularly ovulation and testosterone production, further demonstrating why prolactin is the key hormone for breast milk synthesis.