If you had COVID-19 during your pregnancy, you have likely wondered what that means for your baby’s immunity. Mothers can transfer protective elements to their babies through a natural process called passive immunity. This provides a temporary defense for the newborn in their earliest months of life.
How Immunity Is Transferred Before Birth
Your body produces proteins called antibodies in response to an infection or vaccination. These antibodies circulate in your bloodstream to fight specific pathogens, like the virus that causes COVID-19. During pregnancy, the placenta acts as a selective gateway between your circulatory system and your baby’s.
This organ facilitates the transfer of nutrients and oxygen, and it also allows certain antibodies to pass to the developing fetus. The primary type of antibody that crosses the placental barrier is Immunoglobulin G (IgG). This transfer is not unique to COVID-19; it is how a mother passes on immunity to diseases like measles and influenza.
The baby’s immune system doesn’t produce these antibodies itself; it receives a pre-made defense system from the mother. This equips the newborn with immediate protection against pathogens it may encounter shortly after birth. The presence of these maternal antibodies is a key part of this in-utero preparation for life.
The Strength and Duration of Newborn Immunity
The level of protection a newborn receives is not absolute and depends on several factors. A primary determinant is the timing of the mother’s infection. Mothers who contract COVID-19 in their third trimester tend to transfer a higher concentration of antibodies because IgG transport across the placenta is most active then.
The immunity your baby receives is temporary. These maternal antibodies degrade over time, with levels declining during the first six months of life. While this passive immunity may not prevent an infection, it can reduce the severity of the illness if the baby is exposed. This provides a buffer while the infant’s own immune system matures.
The concentration of antibodies in the cord blood of newborns is positively correlated with the levels in the mother’s blood. Symptomatic mothers often have higher antibody concentrations, which leads to higher antibody levels in their babies. However, not all babies will have detectable antibodies, especially if the mother’s own antibody levels were low.
Comparing Immunity from Infection vs. Vaccination
A mother can pass on antibodies through two main routes: natural infection or vaccination. Both result in the transfer of protective antibodies to the baby, but there can be differences in the resulting immunity. Immunity from a natural infection can be variable, depending on the illness’s severity and timing.
COVID-19 vaccination during pregnancy also leads to the transfer of protective antibodies. Research suggests vaccination may generate a more robust immune response than a natural infection. Vaccine-induced antibodies can be present in higher, more consistent levels, which could lead to a greater transfer of these proteins to the fetus. This provides a way for mothers to offer newborns protection without experiencing the illness of COVID-19 itself.
The Role of Breastfeeding in Passing Antibodies
After birth, another layer of immune protection can be transferred from mother to baby through breastfeeding. This process is distinct from the antibody transfer during pregnancy. Breast milk, particularly colostrum, is rich in a different type of antibody called Immunoglobulin A (IgA).
Unlike IgG antibodies that circulate in the baby’s bloodstream, IgA antibodies work on a localized level. They coat the mucous membranes in the baby’s nose, throat, and gastrointestinal tract. This coating acts as a protective barrier, neutralizing pathogens at their point of entry.
Even after the placentally-transferred antibodies wane, breastfeeding can continue to provide immune support. The antibodies in breast milk reflect the mother’s current immune status, offering protection against recent pathogens.
Recommended Steps for Protecting Your Newborn
Passive immunity from the mother is beneficial but does not provide complete protection for your newborn. You should take additional steps to create a safe environment for your baby. One strategy is “cocooning,” which involves ensuring all caregivers and close family members are up-to-date on their vaccinations.
Practicing good hand hygiene is another effective measure. Anyone who handles the baby should wash their hands thoroughly with soap and water. Limiting your newborn’s exposure to large crowds and sick individuals can also reduce their risk of infection.
Follow the guidance of your pediatrician, who can provide personalized advice based on your family’s circumstances. They can offer the most current recommendations for keeping your baby safe and healthy. These measures, combined with passive immunity, help safeguard your newborn.