Which hormone is secreted by the pituitary gland for milk production?

The hormone secreted by the pituitary gland that plays a crucial role in milk production is prolactin. Prolactin is primarily responsible for the initiation and maintenance of lactation in breastfeeding mothers. When a woman gives birth, prolactin levels rise, stimulating the mammary glands to produce milk.

Prolactin's action is essential during the postpartum period, as it not only promotes milk production but also works in conjunction with other hormones to facilitate the breastfeeding process. While estrogen and oxytocin also have roles related to lactation—estrogen helps develop breast tissue and oxytocin aids in milk ejection—neither directly stimulates milk production as prolactin does. Testosterone does not have a role in lactation in females and is primarily associated with male reproductive functions. This context reinforces why prolactin is the correct choice for a hormone that directly influences milk production.