Which hormone is primarily responsible for stimulating milk production in females?

Prolactin is the hormone primarily responsible for stimulating milk production in females. It is produced by the anterior pituitary gland and plays a crucial role in lactation. After childbirth, increased levels of prolactin promote the production of breast milk, ensuring that nursing mothers can provide adequate nutrition to their infants.

While estrogen, oxytocin, and progesterone have important roles in reproductive health and pregnancy, they do not directly stimulate milk production to the same extent as prolactin. Estrogen prepares the breasts for lactation and helps with breast tissue growth, progesterone supports pregnancy, and oxytocin is involved in the milk ejection reflex, helping to release milk during breastfeeding. However, none of these hormones directly induce the synthesis of milk as prolactin does. Thus, prolactin's primary function in promoting milk production is why it is the correct answer.