The Lifesaving Shield: How Maternal Antibodies Protect Babies from Measles
Measles is one of the most contagious viral infections, spreading rapidly among unvaccinated individuals and posing a significant threat to infants too young to receive the measles, mumps, and rubella (MMR) vaccine. Fortunately, nature has a built-in defense: maternal antibodies, passed from mother to baby, provide essential protection in the early months of life. These antibodies cross the placenta during pregnancy and continue to be delivered through breast milk after birth, helping to safeguard newborns until they can be vaccinated.
Understanding how maternal antibodies work—and how mothers can ensure they provide the best protection for their babies—can make a critical difference in preventing measles outbreaks and reducing infant vulnerability.
How Do Maternal Antibodies Work?
Maternal antibodies are specialized proteins produced by the immune system that help recognize and neutralize infectious diseases. When a woman has immunity to measles—either through vaccination or past infection—her body produces measles-specific antibodies. These protective proteins can be transferred to her baby in two key ways:
Through the Placenta: During pregnancy, antibodies travel across the placenta to the baby, providing passive immunity that lasts for several months after birth. This transfer process is most effective in the third trimester, ensuring that babies born to immune mothers have some level of protection against measles immediately after birth.
Through Breast Milk: After birth, breastfeeding continues to provide immune support. Breast milk contains additional antibodies that help protect the baby from infections, including measles. While these antibodies do not provide as strong or long-lasting protection as those transferred through the placenta, they still play a vital role in supporting the infant’s developing immune system.
However, these maternal antibodies gradually wane, typically disappearing between 6 to 12 months of age, leaving a window of vulnerability before the baby can receive the first dose of the MMR vaccine at 12 months old.
The Dangers of Congenital Measles
Measles is particularly dangerous for pregnant women and their babies. If a mother contracts measles during pregnancy, the consequences can be severe. Measles infection in pregnancy can lead to:
Miscarriage
Premature birth
Low birth weight
Stillbirth
In rare cases, the virus can pass directly to the baby, leading to congenital measles—a serious condition that can cause severe respiratory infections, brain inflammation, and long-term developmental problems. Babies born with congenital measles are at high risk of complications, including pneumonia and long-term neurological damage.
Because measles is so contagious—spreading through respiratory droplets and remaining airborne for hours—unvaccinated individuals, including mothers and caregivers, can unknowingly expose vulnerable infants to the virus. Ensuring maternal immunity before or soon after pregnancy is one of the most effective ways to protect newborns.
How Can Mothers Ensure Their Babies Are Protected?
There are several proactive steps mothers can take to ensure their babies receive strong immunity against measles:
1. Testing for Immunity During Pregnancy
Pregnant women who are unsure of their measles immunity can get tested to check for protective antibodies. This simple blood test helps determine if the mother is already immune or if she will need the MMR vaccine after giving birth.
2. Postpartum Vaccination and Breast Milk Protection
Women who are not immune can receive the MMR vaccine immediately after giving birth. While this vaccination does not directly protect the newborn at birth, it prevents the mother from contracting and spreading measles to her baby. Additionally, the antibodies generated by the vaccine can be passed through breast milk, offering some level of immune protection to the breastfeeding baby.
Breastfeeding after receiving the MMR vaccine provides another layer of defense, helping to reduce the baby’s risk of infection in the months before they receive their own vaccination.
3. Keeping Close Contacts Vaccinated
Since newborns rely on passive immunity, it is essential that those around them—parents, siblings, caregivers, and extended family members—are fully vaccinated. This strategy, known as cocooning, helps reduce the risk of exposure and keeps the infant protected until they are old enough to receive their own MMR vaccine.
4. Prioritizing Infant Vaccination
Maternal antibodies are temporary, and the best long-term protection against measles comes from vaccination. Babies should receive their first dose of the MMR vaccine at 12 months of age, followed by a second dose between 4 to 6 years old. In areas where measles outbreaks are common, an early first dose at 6 months old may be recommended, though this should be followed by the routine two-dose schedule for full immunity.
Building a Strong Foundation for Baby’s Health
Measles remains a global threat, but maternal immunity offers newborns a crucial first line of defense. By ensuring that mothers are immune—either before pregnancy or through postpartum vaccination—we can help protect infants during their most vulnerable months.
If you are pregnant or planning to become pregnant, talk to your healthcare provider about measles immunity testing and postpartum vaccination options. By staying informed and proactive, we can collectively work to eliminate measles transmission and keep our babies safe.
