Breastfeeding and the Infant Immune System
Many parents want their baby to be breastfed because of the protection it offers the immature immune system. Yet most people have little understanding of what this protection is or how it works.
During pregnancy, the foetus has the protection of the placenta, where the mother's blood supply passes close enough to that of the unborn baby that there can be an exchange between the two.
During breastfeeding, a similar process occurs during every feed. The vacuum created by the baby’s suckling releases milk from the breast in one direction but the reverse action draws the baby's saliva back into the breast ducts! And this is where the magic happens.
The breast tissue receives any bacteria or viruses the baby has been exposed to, even before they show symptoms of infection. The mother’s immune system then produces specific antibodies and sends them back to the baby through the breastmilk. This happens multiple times a day, every time the baby feeds directly at the breast. The milk also passes on the mother's existing antibodies and any she develops after her own exposure to infection.
Breastfeeding also helps the development of the infant’s own immune system. Breastfed babies have a larger thymus gland than babies who are not breastfed. The thymus gland develops white blood cells which fight infections.
This constant support from the mother's immune system is why babies who are not breastfed are much more likely to be admitted to hospital with common infections of the respiratory and digestive systems. Breastfed babies may still become unwell but are less likely to need hospitalisation in the first year of life. Their mother's immune system helps the baby fight infection.
This process relies on the baby feeding at the breast. Babies who are mostly or exclusively fed expressed breastmilk from a bottle probably don't have quite the same protection. More research needs to be done in this area.
The immune support continues throughout the breastfeeding season, whether it is measured in months or years. The child’s immune system matures around 7-8 years of life, peaking in function around puberty before gradually declining over a lifetime. Breastfeeding builds the foundation of a healthy immune system from the very first feed.
