Pennsylvania Reports Rise in Congenital Measles Cases

The Pennsylvania Department of Health alerted doctors Monday to a rise in measles infections among pregnant women and a troubling increase in congenital measles, a condition the state says is rarely, if ever, seen in the United States, according to NBC News.

The alert comes as Pennsylvania's measles outbreak, which began in April, continues to expand. State officials said 66 pregnant women have been diagnosed with measles since the outbreak started, and that the virus carries specific risks for both mother and child, NBC News reported.

How many pregnant women have been infected in Pennsylvania?

Pennsylvania's health department said 66 pregnant women have contracted measles since the outbreak began in April, according to NBC News. A department spokesperson said in an email cited by NBC News that "getting measles while pregnant increases the risk of miscarriage, early labor, and low birth weight."

The department has not disclosed how many of those pregnancies ended in miscarriage or produced infants with congenital measles. State law bars the release of those outcome details, and there is no national database that tracks congenital measles cases, NBC News reported. Health officials also noted that the true case count may be undercounted because the outbreak has been concentrated largely among Amish families who do not always seek conventional medical care.

What is congenital measles and how does a baby contract it?

According to the American Academy of Pediatrics, as reported by NBC News, congenital measles occurs in newborns whose mothers were infected during the two weeks before delivery and who test positive for the virus or develop symptoms within 10 days of birth. The AAP added a frequently-asked-questions page on congenital measles to its website last month in response to the ongoing and growing outbreaks nationwide, per NBC News.

Congenital measles was rare even before widespread vaccination became available, largely because most women of childbearing age had already been infected with measles as children and carried immunity into pregnancy. The condition is now emerging as a threat specifically because measles outbreaks are increasing as vaccination rates decline, NBC News reported.

How many babies have been affected so far?

Doctors have told NBC News anecdotally that at least six babies have been born in Pennsylvania with congenital measles. Symptoms in affected newborns can range from rash and fever to pneumonia, neurological complications, and low blood platelet counts, according to the report. At least two of the babies developed pneumonia severe enough to require admission to an intensive care unit, doctors told NBC News.

The disease can be fatal. NBC News reported that one father in Lancaster County said his wife contracted measles in August and went into labor a month early; their baby died shortly after birth.

How large is Pennsylvania's broader measles outbreak?

Pennsylvania has recorded 1,286 measles cases as of Monday, according to the state health department figures cited by NBC News. Nationally, the Centers for Disease Control and Prevention counted 4,410 measles cases in the U.S. this year as of last Thursday, per the NBC News report. The outbreak in Pennsylvania, now in its seventh month, has been concentrated in communities where vaccination rates are lower, contributing to sustained transmission.

Why is this considered a new kind of risk in the U.S.?

For decades, congenital measles was effectively absent from American medicine because near-universal childhood vaccination, combined with natural immunity from earlier generations' infections, meant pregnant women rarely encountered the virus. The current resurgence reflects falling vaccination coverage in specific communities rather than a change in the virus itself. Pennsylvania's alert to physicians is intended to help doctors recognize and respond to measles symptoms in pregnant patients and newborns that many practicing clinicians have never previously seen in a clinical setting, based on the state's description of the outbreak to NBC News.

The department's inability to publicly detail pregnancy outcomes, combined with the absence of a national tracking system for congenital measles, means the full scope of harm from the outbreak — including miscarriages and infant deaths — is not fully known, NBC News reported. Officials have not indicated when or whether additional outcome data might become available as the outbreak continues.

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