Which hormone is primarily responsible for milk production?

Prolactin is the hormone primarily responsible for milk production in the breasts following childbirth. It is produced by the anterior pituitary gland and plays a crucial role in the development of mammary glands during pregnancy and in the initiation and maintenance of lactation after delivery. Prolactin levels rise significantly during pregnancy, preparing the body for breastfeeding.

In contrast, oxytocin is important for the milk ejection reflex, promoting the release of milk during breastfeeding but not its production. Progesterone and estrogen, while significant for breast development and preparing the body for potential lactation, do not have a direct role in producing milk. Estrogen helps with the growth of ducts in the breast, while progesterone is responsible for preparing the lobules for milk production, but it does not stimulate the actual lactation process. Thus, prolactin is essential for the synthesis of milk, affirming its primary role in this physiological process.