Physiology of Breastfeeding
Physiology of Breastfeeding

When your baby suckles on the nipple, your pituitary gland secretes a hormone known as prolactin, which then stimulates milk gland cells to produce milk in the breast. Next, the hormone oxytocin is released, causing the cells around the milk gland to squeeze milk out of the nipples, causing the ‘let-down’ which is often characterised by:

  • Tingling 
  • A feeling of fullness in the breasts 
  • A warm sensation in the upper body

Let-downs can also be caused by:

  • Hearing your baby, or any baby, cry 
  • Thinking of your baby when you’re away, or looking at a picture of your baby - this is one of the most amazing examples of “mind over matter” your body will ever experience 
  • Seeing or smelling other babies 
  • Manual expression or expressing your breast milk with a breast pump 
  • Warm water (although this typically only occurs in the early days of breastfeeding)

Related breastfeeding stories:

Benefits of breastfeeding 
Breast milk supply 
Find out more about the let down

This article was written for Kidspot, New Zealand's leading pregnancy and parenting resource.

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