Measles is making a comeback in the United States, and this time it's hitting adults harder than ever. Nearly one-third of measles cases in 2025 occurred in adults aged 20 and older, and that trend continued into 2026 with about one-quarter of cases in this age group. For pregnant women, this shift is particularly concerning because pregnancy changes how the body fights infections, making expectant mothers more vulnerable to serious measles complications.

Why Is Measles Suddenly a Threat for Pregnant Women?

Measles is a highly contagious virus that spreads through the air when someone coughs or sneezes. The numbers are staggering: up to nine out of 10 unvaccinated people who come into close contact with someone who has measles will become infected. During 2025, about one in 10 people with measles required hospitalization.

Pregnancy fundamentally changes how a woman's immune system works, and these changes increase the risk of serious illness from measles. If you're pregnant and contract measles, you face a higher chance of being hospitalized, developing pneumonia, and in rare cases, death. Beyond the mother's health, measles during pregnancy can harm the developing baby in several ways.

• Pregnancy Loss: Measles infection during pregnancy can lead to miscarriage or stillbirth.
• Preterm Birth: Babies may be born earlier than expected, requiring intensive care.
• Low Birthweight: Infected pregnancies often result in smaller babies who face additional health challenges.
• Newborn Illness: If measles passes from mother to baby during pregnancy, newborns can develop serious illness and hearing loss.
• Long-Term Brain Condition: Very rarely, a fatal brain condition called subacute sclerosing panencephalitis (SSPE) can develop years after birth.

Even after birth, unvaccinated babies too young to receive the measles vaccine remain at high risk if exposed to the virus.

How Can Pregnant Women Protect Themselves and Their Babies?

The best defense against measles is the MMR (measles-mumps-rubella) vaccine. However, timing matters significantly for pregnant women. The MMR vaccine is a live vaccine, meaning it contains a weakened form of the virus, so it's not recommended during pregnancy. Instead, the ideal time to get vaccinated is at least one month before becoming pregnant.

If you're already pregnant and unsure about your immunity, talk with your healthcare provider. They can test whether you have protection against measles. If you're not immune and weren't vaccinated before pregnancy, the vaccine can be given after delivery, even while breastfeeding.

Steps to Prepare for Measles Protection During Pregnancy

• Check Your Vaccination Status: Before becoming pregnant, confirm with your healthcare provider whether you received the MMR vaccine and have immunity to measles.
• Get Vaccinated Early: If you're not immune, receive the MMR vaccine at least one month before trying to conceive.
• Protect Your Household: Encourage partners, family members, and caregivers to be up to date on MMR vaccination to create a protective barrier around you and your baby.
• Monitor Local Outbreaks: If a measles outbreak is occurring in your area, follow local health recommendations and avoid crowded public settings when possible.
• Know the Symptoms: Watch for fever, cough, runny nose, red eyes, and rash, especially if you've traveled or live in an outbreak area.

What Should You Do If You're Exposed to Measles While Pregnant?

If you believe you've been exposed to measles during pregnancy, call your healthcare provider's office immediately. For pregnant women who are not immune to measles or unsure of their immunity status, healthcare providers may administer immune globulin (IG) after an exposure. This treatment provides antibodies that can help prevent or reduce the severity of measles infection.

If you develop symptoms of measles while pregnant, such as fever and rash, contact your healthcare provider right away, especially if you live in an area with measles activity or have recently traveled. Be sure to mention your vaccination history and travel details. Managing fever during early pregnancy is important, as prolonged fever can pose risks to the developing baby. However, high-dose vitamin A supplements are not recommended during pregnancy because they can increase the risk of certain birth defects.

After delivery, measles is not transmitted through breast milk, so breastfeeding can continue safely. Your healthcare team may recommend precautions such as wearing a mask during close contact with your newborn or having another healthy person feed your expressed breast milk to minimize transmission risk.

"If you are pregnant or breastfeeding and unsure about your immunity to measles or worried about exposure, you are not the only one with these questions. Your healthcare provider and MotherToBaby are here to help answer any questions you may have," noted experts from the Centers for Disease Control and Prevention.

Centers for Disease Control and Prevention, MotherToBaby

The resurgence of measles among adults underscores the importance of vaccination before pregnancy. If you're planning to become pregnant or are already expecting, having an open conversation with your healthcare provider about measles immunity should be part of your prenatal care. The protection you gain through vaccination doesn't just safeguard your own health; it also shields your baby from a potentially serious infection during one of the most vulnerable periods of life.