The report could fill major gaps about a condition doctors have rarely seen for decades.

Federal health scientists are trying to alert doctors to the risks of measles during pregnancy as U.S. cases surge, but how quickly that information will reach clinicians — and where it will be published — remains uncertain amid internal conflict, according to five people familiar with the discussions.

Centers for Disease Control and Prevention scientists sought to notify clinicians on the rising threat about a month ago through its Health Alert Network and provide guidance for care, according to two people briefed on the process who, like others, spoke on the condition of anonymity to share internal deliberations.

State health officials had been seeking more information, one of the people said, because clinicians are seeing unvaccinated women of childbearing age with measles for the first time, the person said. The CDC typically uses this network to rapidly convey urgent public health information to clinicians, laboratories and public health professionals.

But the alert, which usually requires sign-off from the CDC director’s office, was not approved, according to two people familiar with the matter, who did not know why.

Unable to send it out through that rapid distribution network, scientists then turned to preparing this information for a report in the agency’s flagship weekly scientific journal, the Morbidity and Mortality Weekly Report (MMWR), where reports go through an extensive internal review and take longer to publish.

A spokesperson with the Department of Health and Human Services (HHS) did not address questions about why the earlier alert was not approved. The CDC is closely tracking measles, and providing clinicians and public health officials with guidance to protect mothers and babies, the spokesperson said, adding that the report is moving through the CDC’s scientific review and clearance process, “which informs publication decisions and timing.”But in recent weeks, other vaccine-related reports that already had cleared the MMWR process have been delayed, according to three people familiar with the process.

Against that backdrop, discussions have turned to publishing the measles information in an outside scientific journal, multiple people familiar with the discussions said. Publishing outside the agency would make clearance less onerous and reduce the potential for political interference or further delays, they said.

Because measles during pregnancy has been so uncommon after the United States eliminated continuous spread of the virus in 2000, many doctors have limited experience recognizing it or treating it. It can cause pneumonia and death in the mother and increase the risk of losing the pregnancy, giving birth prematurely and having a baby with low birth weight. The virus can also pass to a fetus and cause congenital measles, which can lead to severe complications, including brain inflammation and death.

The report would be the first national accounting of measles in pregnancy during the current resurgence of the virus, two of the people familiar with the matter said.

“These are unprecedented knowledge gaps. Who on earth would have thought we needed to know this stuff?”Marrazzo said. “The fact that no national authority has been tracking the numbers and trying to come up with optimal management speaks to the profound vacuum that we’re in in terms of any guidance.”The number of measles cases has reached a 35-year high for the country, with the United States recording 4,852 cases so far this year, more than twice the number reported in all of 2025, according to the CDC. Pennsylvania, home to the country’s largest current outbreak, had recorded nearly 1,400 cases as of Wednesday, accounting for almost one-third of all U.S. cases this year.

“We don’t have data on this part. The experience is limited,” Barton said. “When I’m dealing with this situation, I’m dealing with not just Jane who’s pregnant, but the baby or babies inside her womb.”Doctors also have to consider family members and other susceptible mothers and babies who could be exposed in obstetric units and neonatal intensive care.

Caring for a pregnant woman with measles can quickly become complicated, she said. A mother can have measles without developing the telltale rash. Premature babies are particularly vulnerable because even those born to vaccinated mothers may be born too soon to receive enough protective antibodies from the mother.

Pennsylvania health officials last week took the unusual step of issuing a statewide health alert specifically addressing measles in pregnancy and congenital measles. The notice urged doctors to immediately report suspected infections and said women should be vaccinated against measles before becoming pregnant. The measles, mumps and rubella vaccine (MMR) cannot be given during pregnancy.

The department said 77 pregnant women in Pennsylvania had been diagnosed with measles since the state’s outbreak began in late April.

It’s unclear how many women have miscarried or delivered babies with congenital measles. The department said that state law prohibits it from releasing details of the outcomes of those pregnancies. There is no national database that tracks cases. True numbers may also be higher because the outbreak has been centered in the Amish community, where families often do not seek preventive or conventional medical care.

The CDC report is being prepared as the outbreak has ignited political fights. Health Secretary Robert F. Kennedy Jr., a longtime vaccine critic, has clashed with Pennsylvania officials over the state’s handling of the outbreak and its measles deaths.

After Pennsylvania reported its first two measles-associated deaths in August, CDC Director Erica Schwartz directed the agency to exclude them from its national tally, The Washington Post previously reported, departing from CDC’s long-standing practice of relying on data from state health departments. The CDC subsequently changed how it counts measles deaths, turning instead to federal death records, which can take weeks to arrive and are not designed to provide real-time information needed to control an ongoing outbreak. As of Thursday, Pennsylvania has reported five measles-related deaths, but the CDC website has recorded three. Local officials have said two deaths were babies.

The pregnancy concern is drawing broader attention from pediatric and infectious-disease specialists. The American Academy of Pediatrics recently issued guidance on congenital measles, and the Infectious Diseases Society of America devoted a session at its annual meeting this month on pregnancy and measles.

Declining measles vaccination rates have helped create the conditions for the highly contagious disease to spread again in the United States. MMR vaccination among U.S. kindergartners has declined over several years and has fallen below the 95 percent needed to prevent outbreaks and protect the vulnerable.

At a Nov. 10-13 meeting, an independent commission convened by the Pan American Health Organization is expected to review whether the United States has maintained the measles elimination status it achieved in 2000, a landmark public health accomplishment.

That status means no continuous transmission of the virus for at least 12 months. Infectious-disease experts say prolonged transmission that began with the West Texas outbreak in early 2025 and continued through outbreaks in Utah and Arizona has put that status in serious jeopardy.

Other CDC research on vaccine-preventable diseases has also encountered publication delays. Two reports on pertussis, or whooping cough, scheduled for publication this week in the MMWR — on Tuesday and Thursday — were postponed, according to two other people familiar with the reports, who spoke on the condition of anonymity to share internal discussions.

The reports examine the rise and severity of pertussis cases in recent years. One looks at the trend of pertussis cases over a period of years and found that most babies who died were born to mothers who did not get the Tdap vaccine during pregnancy, which protects infants, who face the greatest risk of severe disease. A second report looked at the severity of cases, and found that almost half of hospitalized patients of all ages had no underlying conditions and most hospitalized young infants had no underlying conditions. Both reports had already been cleared for publication when their release was pushed last Thursday to the second week of November, the people said.

The HHS spokesperson said the CDC is closely tracking pertussis and providing guidance to protect mothers and babies, and that the reports are moving through scientific review and clearance, which informs publication decisions and timing.

Pertussis cases have risen sharply in recent years. After falling during the pandemic, they surged from 7,063 cases in 2023 to more than 35,000 in 2024. Cases remained elevated in 2025, with nearly 29,000 reported, but preliminary data show infections declining in 2026, according to the CDC.