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Your Baby's Developing Immune System: what you need to know
Your Baby's Developing Immune System: what you need to know
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Written by Emily Greenberg
Updated over 2 weeks ago

Our immune systems consist of white blood cells, antibodies, and other components that fight off harmful invaders like bacteria, viruses, and pathogens. With such an important function, it can be scary for new parents to realize their baby has an underdeveloped immune system. Here's everything you need to know about your baby's immunity.

What is my baby's immune system like at birth?

Newborns are most vulnerable to germs since their immune systems will take time and maturity to build. This vulnerability is exacerbated for premature babies, whose immune systems are even weaker than a full-term baby.

However, the mother-baby dynamic has built-in boosters that give babies immunity before their immune systems work effectively. This is known as "passive immunity" instead of "active immunity."

  • Before birth,your placenta delivers antibodies (special proteins that fight pathogens) to your baby through the placenta. How many and what kind of antibodies your baby gets will depend on your immune system.

  • During childbirth,good bacteria in the birth canal get passed on to the baby during vaginal deliveries, bolstering their immune system. This is referred to as "microbial transfer." What about C-section babies? There is emerging research to identify a way to remedy this missed transfer.

  • After birth,initiating breastfeeding will deliver more passive immunity as more antibodies are in your colostrum and breast milk.

How long will it take for baby's immune system to develop?

Passive immunity from birth can help young babies for the first 3-6 months, and continuing to breastfeed will extend passive immunity benefits.

Babies build active immunity shortly after birth as they are exposed to germs and begin immunizations. Both natural and vaccine-induced exposures help the immune system learn to identify and fight pathogens directly.

However, it takes about 7-8 years for the immune system to strengthen. This is why young children are often sick, too. It takes time!

How to support your baby's developing immunity

Supporting your baby's immune system entails proper nutrition, breastfeeding if possible, ensuring they receive necessary vaccinations, and maintaining good hygiene to reduce exposure to harmful pathogens.

How cautious is too cautious?

Some exposure to germs is normal and what helps their immune system develop. Being overly cautious may hinder the natural strengthening of their immune system. Consult your pediatrician to discuss risk tolerance if you feel anxious or unsure.

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