Pituitary hormone that stimulates formation of milk is

Prolactin is the pituitary hormone responsible for stimulating the formation and production of milk in the mammary glands. During pregnancy and after childbirth, prolactin levels increase. It helps prepare the mammary glands for milk production and secretion. After delivery, the drop in other hormones like estrogen and progesterone allows prolactin to exert its effects fully. Prolactin stimulates the alveoli (small sacs in the mammary glands) to produce milk, and it also helps with the transport of milk through the milk ducts.