COVID-19 infection in pregnancy may raise baby's risk of respiratory illness

Babies born to COVID-infected mothers have triple the risk of developing a breathing disorder that normally affects preemies, a new study shows.

Researchers found that exposure to the coronavirus while in the womb increased a newborn's risk of respiratory distress syndrome by sparking an "inflammatory cascade" in the infants that affected their breathing.

"We found unusually high rates of respiratory distress shortly after birth in the full-term babies born to mothers who had COVID-19 during pregnancy," senior study author Dr. Karin Nielsen, a professor of pediatrics in the division of pediatric infectious diseases at the David Geffen School of Medicine at UCLA, said in a university news release.

The research team also found that the risk was significantly lower if moms infected during pregnancy had been vaccinated, according to findings published Wednesday in the journal Nature Communications.

Respiratory distress syndrome most commonly afflicts premature babies born with underdeveloped lungs, according to the Children's Hospital of Philadelphia.

Babies with the syndrome breathe rapidly and struggle to catch their breath. They also can have blue coloring, flaring of the nostrils and make grunting sounds while breathing.

For the new study, researchers enrolled 221 mothers, of whom 68% were unvaccinated prior to infection. All babies included in the study were born at full term.

Severe COVID-19 infections occurred in 23 of the unvaccinated mothers, compared to 3 vaccinated moms.

Researchers found that 17% of 199 infants exposed to COVID-19 in the womb developed respiratory distress - far higher than the 5% to 6% of babies that typically suffer respiratory distress in the general population.

About 21% of babies with respiratory distress were born to moms who had severe COVID-19, while only 6% of babies without respiratory distress had been exposed to severe COVID-19.

Researchers also found more cases of respiratory distress at later ages than expected in the infants, when their lungs should have developed enough to minimize their risk.

Of the 34 infants with respiratory distress, only five were born to moms vaccinated prior to infection, results show.

On the other hand, 63 babies born to vaccinated moms didn't have the breathing disorder, indicating that vaccination protected their lungs.

Researchers said even a single dose of mRNA COVID-19 vaccine prior to infection significantly reduced the risk that a full-term infant would develop respiratory distress.

Researchers also came up with a potential reason why COVID-19 might increase this risk.

In the lab, they observed that whip-like hairs called motile cilia that help clear mucus from the respiratory tract did not function normally in babies with respiratory distress linked to COVID-19 exposure.

The babies also had higher levels of immunoglobulin E, an antibody linked to allergic response.

More information

The Children's Hospital of Philadelphia has more about respiratory distress syndrome.