Babies primarily get immunity from their mothers through the placenta during pregnancy and through breast milk after birth.
Here's a breakdown of how this works:
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During Pregnancy:
- Placental Transfer: A mother's antibodies are actively transported to the baby through the placenta, mainly during the third trimester (the last three months) of pregnancy. These antibodies are IgG antibodies, and they provide what's known as passive immunity to the baby. This means the baby is receiving ready-made antibodies, not producing them themselves. The types of antibodies transferred depend on the mother's own immunity, meaning the baby is protected against diseases the mother has either had or been vaccinated against. This protection is temporary, typically lasting for several months after birth, as the antibodies gradually break down.
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After Birth:
- Breast Milk (Especially Colostrum): Breast milk, especially the first milk produced after birth called colostrum, is rich in antibodies (primarily IgA), white blood cells, and other immune factors. These antibodies coat the baby's digestive tract, providing local protection against infections. This passive immunity helps protect the baby until their own immune system matures. Breastfeeding also helps to stimulate the baby's own immune system.
In summary, babies are born with some immunity passed on from their mothers and continue to gain immunity through breastfeeding. This helps protect them until their own immune system is fully developed and can start producing antibodies on its own through exposure to antigens (either through infection or vaccination).
