Pennsylvania Warns Doctors About Congenital Measles as 66 Pregnant Women Contract the Virus

The Pennsylvania Department of Health has issued a health alert warning doctors about congenital measles, an infection passed from mother to baby in the womb that was once extremely rare in the United States, after dozens of pregnant women in the state contracted measles during the state’s ongoing measles outbreak.

So far, the state says 66 pregnant women have contracted measles while pregnant this year, and at least six babies have been born with measles, according to CIDRAP, which reported the alert. Of six deaths reported in the state, at least two were in infants, though it is not known whether those infants had congenital infections. Releasing information on infant outcomes is illegal under Pennsylvania law, and there is no national database tracking congenital measles, according to the report.

Congenital measles is defined narrowly: only infections that occur in the last two weeks of pregnancy or the first 10 days after delivery count as congenital. Dr. Adam J. Ratner, a member of the American Academy of Pediatrics Committee on Infectious Diseases, told CIDRAP that “we don’t have denominator data on congenital measles,” meaning there is no firm basis for estimating how often infected pregnant women have infants with the condition. He said prenatal measles is likely underreported because mild cases in pregnancy may not be picked up. A 2025 Canadian case series described 51 pregnant women who contracted measles, resulting in nine cases of congenital measles; one of those infants died.

What the state is telling doctors

The alert urges women to get the measles, mumps and rubella (MMR) vaccine before pregnancy. The vaccine is not recommended once pregnancy begins because it contains live virus. If an unvaccinated pregnant woman is exposed to measles, she has a six-day window to receive immunoglobulin therapies; a woman who received the two-dose MMR series in childhood should be well-protected, according to the alert.

The presentation of congenital measles is “highly variable, ranging from asymptomatic, to the classic measles rash, to fulminant, multisystem disease and death,” the state health department said. Treatment is supportive care, plus vitamin A for symptomatic infants unless it is contraindicated. Asymptomatic infants born to mothers with active infections (rash onset within 14 days of birth) could also receive immunoglobulin.

Pennsylvania has confirmed 1,286 measles cases, 109 of them reported in the past week. The state’s dashboard lists five measles deaths; a sixth death, reported in Franklin County, is still under investigation. The state said the death would not be labeled “measles-associated” until there is evidence of a measles infection and a positive laboratory test in the 30 days before death.

Reporting based on coverage by CIDRAP and KFF Health News.