Parenting tip

When your baby starts sucking at your breast, the hormone oxytocin is released, causing the muscle cells around your milk glands to contract and squeeze out breastmilk.

About breastfeeding

This article explains how breast milk is produced by mums and describes various aspects of breastfeeding related to feeding frequency and changes in your milk.

Women produce colostrum, the special early milk, from about halfway through pregnancy and for the first few days after birth.

Colostrum is an amazingly rich mixture of proteins, vitamins (such as vitamin A) growth factors, enzymes and anti-infective agents. With regard to breastfeeding, all of these features of early breast milk help your newborn through the first three to four days of life. Although it is small in quantity, as your baby has a small digestive system, it is packed with nutrients and antibodies that help give your baby more resistance to infections. Colostrum also has a laxative effect which helps your baby get rid of the meconium (black sticky poo) from their gut after birth.

A few days after your baby’s birth, the colostrum gradually becomes mature milk with a different balance of proteins, carbohydrates, fats, vitamins and minerals. Both colostrum and breastmilk contain many special factors to help:

  • absorb nutrients
  • prevent infections
  • your baby’s gut to develop and
  • her immune system to mature.

Breastmilk changes according to your baby’s needs. For instance there are more sleep inducing factors in breastmilk in the evening. During each feed breastmilk also adapts to your baby’s needs. At first it is more thirst quenching; as the feed continues and the milk producing cells are squeezed, creamier milk is released, so that the milk at the end of the feed is more satisfying.

The let-down reflex – making milk available

When your baby starts sucking at your breast, the hormone oxytocin is released, causing the muscle cells around your milk glands to contract and squeeze out breastmilk. This ‘squeezing’ is known as the let-down reflex and this hormone also helps shrink your uterus after birth. Some mums feel the let-down reflex as a tingling in the breast but not everyone does. There may be a number of ‘let downs’ every time you breastfeed, and you may or may not be aware of them.

Breastfeeding frequency

Milk production is stimulated by the removal of milk from the breast, i.e. your baby drinking the milk or expressing. Babies have very small stomachs at first and need to feed frequently to build up your milk supply. After a while, baby and breast start to work in harmony, with your breast milk production matching his needs. Increasing breast milk supply happens naturally in response to increased demand from your baby: the more milk he needs and drinks, the more you make.

Changes in your breast milk

The fat content of your milk increases as the milk is removed, so when breasts are relatively less full, the fat content is proportionately higher; when your breasts are relatively more full, the fat content is proportionately lower. Healthy, effectively feeding babies will get the right milk intake and type of milk for them. This also means you don’t need to worry about whether your baby is getting a certain amount of ‘foremilk’ (the name given to the lower fat milk) and ‘hind milk’ (the name of the higher fat milk).

Further information

NCT supports all parents, however they feed their baby. If you have questions, concerns or need support, you can speak to a breastfeeding counsellor by calling our helpline on 0300 330 0700, whether you are exclusively breastfeeding or using formula milk. Breastfeeding counsellors have had extensive training, will listen without judging or criticising and will offer relevant information and suggestions. You can also find more useful articles here.

National Breastfeeding Line (government funded): 0300 100 0212

UK Association of Milk Banking has information on its network of milk banks across the UK.

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