How does your body make breastmilk?


The structure of the breast

  • Breasts are made up of lobes, which is where the breast milk is made and stored. The lobes look like bunches of grapes and tiny muscles squeeze milk out of them when it is needed. There are ducts in the nipple and the milk come out of these tiny holes, in response to your baby’s sucking. The rest of the breast is made up of connective tissue, nerves, blood vessels and fatty tissue.
  • The Montgomery Glands on the areola of the nipple become more pronounced in pregnancy and their job is to keep the areola and the nipple lubricated and protected so you don’t need to prepare your nipple for breastfeeding.
  • Throughout pregnancy, your body is changing and your breasts are getting ready to feed your baby. The blood vessels become bigger, ensuring that the breasts have enough blood to make milk.


Making milk

  • From about six months pregnant your breasts will start to make colostrum, which is rich in antibodies and protein and it is normal to leak a little bit of milk.
  • After the birth of your baby, when the placenta is delivered, the progesterone levels will fall but the prolactin levels will remain high and more blood will flows to your breasts in preparation of making more milk. When your milk comes in at around days 3-5 after the birth of your baby, your breasts will produce a lot of milk and it starts to change from colostrum to mature milk. During this first week after the birth of your baby it is important to feed your baby regularly to increase the number of prolactin receptors in your breasts.
  • After a feed, your breast may feel empty but your body keeps producing milk. When your baby sucks at your breast, your body will release oxytocin, which causes the muscle cells around the alveoli to contract, pushing milk down through the ducts to the nipple. This is called the milk-ejection or let-down reflex and you may feel a tingling feeling in the breast. This reflex makes the milk available to your baby at the nipple and your body responds by making more milk.
  • You do not have to wait for your breasts to ‘fill up’ before feeding your baby – there is always milk available for your baby.