Which hormone is crucial for milk ejection during breastfeeding?

Oxytocin is the hormone crucial for milk ejection during breastfeeding. It is produced in the hypothalamus and released by the posterior pituitary gland in response to stimuli such as the baby suckling at the breast. When oxytocin is released, it causes the smooth muscle cells surrounding the milk-producing alveoli in the mammary glands to contract. This contraction leads to the expulsion of milk into the ducts, allowing it to be delivered to the infant.

Understanding the role of oxytocin highlights its importance not only in milk ejection but also in promoting maternal bonding and facilitating the breastfeeding process. This makes it a significant hormone in lactation and maternal-infant interactions. While prolactin is essential for milk production, it does not play a direct role in the ejection of milk; instead, it is more associated with stimulating the mammary glands to produce milk. Estrogen and cortisol have different roles in physiology and are not directly involved in the milk ejection reflex.