What stimulates the lobules and the letdown reflex to secrete milk during breastfeeding?

The letdown reflex, which is crucial for breastfeeding, is primarily stimulated by oxytocin. This hormone is released from the posterior pituitary gland in response to suckling by the infant. When a baby latches onto the breast and suckles, sensory nerves in the nipple send signals to the brain, prompting the release of oxytocin. This hormone then acts on the myoepithelial cells surrounding the milk-producing lobules in the breast, causing them to contract and push milk into the ducts, facilitating its flow to the nipple.

In addition to the letdown reflex, oxytocin also plays a role in maternal bonding and can help with uterine contractions post-delivery. Understanding the role of oxytocin in this process highlights its importance in ensuring that breastfeeding can effectively occur, providing essential nutrition for the infant. Other hormones, like prolactin, are involved in the production of milk, but it is the action of oxytocin that directly triggers the release of milk during breastfeeding.