Study details

For the study, researchers from Massachusetts General Hospital examined the medical records of more than 18,100 women who gave birth between March 1, 2020, and May 31, 2021.

Among 861 women who tested positive for COVID-19 during pregnancy, 140, just over 16%, gave birth to a child who later received a neurodevelopment diagnosis by the age of three such as autism or delays in speech and motor development. Meanwhile, fewer than 10% of the remaining children from pregnancies that did not have COVID-19 received a similar diagnosis.

According to the researchers, having a COVID-19 infection during pregnancy was associated with a 29% increased risk of a neurodevelopmental condition in children, after adjusting for other risk factors.

The researchers noted that very few of the women in the study had received a COVID-19 vaccine, as they were not widely available at the time.

The researchers also cautioned that the findings don't prove a causal relationship between COVID-19 and the neurodevelopmental conditions diagnosed in children but instead signal an association between maternal infection and those outcomes.

Discussion

Scientists say it's rare for respiratory viruses like the flu or COVID-19 to cross the placental barrier, and that the impact on the fetus could be because of a mother's immune response. One possible cause could be inflammation, which results in the release of signaling molecules that could influence how neurons in the brain grow, connect, and migrate.

"If the fetus's immune system gets really revved up, that could have downstream consequences, not just for the developing brain, but also for the metabolic system, the liver, the pancreas, the heart, the adipose tissue," said Andrea Edlow, a physician scientist at Massachusetts General Hospital, associate professor of obstetrics and gynecology at Harvard Medical School, and a coauthor on the study.

The American College of Obstetricians and Gynecologists recommends that pregnant people get vaccinated against COVID-19, and federal officials currently say that all Americans should consult a medical provider about getting a COVID-19 vaccine, regardless of their risk factors.

Mary Ann Comunale, an associate professor at Drexel University's College of Medicine, said the study provides important evidence-based information for discussions between clinicians and patients.

"This is particularly important in the current climate of vaccine hesitancy," she said.

"Parental awareness of the potential for adverse child neurodevelopmental outcomes after COVID-19 in pregnancy is key," said Lydia Shook, a maternal-fetal medicine specialist at Massachusetts General Hospital and lead author of the study. "By understanding the risks, parents can appropriately advocate for their children to have proper evaluation and support."

Some experts also noted limitations to the study. Lisa Croen, senior research scientist at the Kaiser Permanente Northern California Division of Research, said that maternal conditions like obesity, hypertension, and gestational diabetes were not controlled for in any of the analyses, "so findings could be confounded by these factors," she said.

Croen said that more research is needed but added that the results of the study do "provide additional, strong rationale for supporting COVID-19 vaccination in pregnancy."