Covid-19 in pregnancy linked to delays in babies reaching milestones

The babies of women who caught covid-19 while they were pregnant during the first year of the pandemic were nearly twice as likely to experience delays in reaching developmental milestones, like babbling and grasping for objects, according to a small study.

The overall risk of developmental delays was still small, though. The babies whose mothers were infected had about a 6 per cent chance of such a diagnosis by the time they were a year old, compared with 3 per cent for those whose mothers didn’t catch covid-19.

“We don’t want to frighten people,” says Roy Perlis at Massachusetts General Hospital in Boston. “The vast majority of babies don’t have any delay.”

Also, the study’s findings are preliminary. Out of the 222 women in the study who tested positive for covid-19 while pregnant, only 14 babies had developmental delays. A larger study could find a larger or smaller effect, says Perlis. Transgender men weren’t included in the study.

Whether any developmental delays are temporary and the affected children will eventually catch up to their peers is also unknown. “It will be really important to get larger cohorts and longer follow-up,” says Perlis. “The goal of our study was to get a sense if there might be some risk.”

Previous research has found that infections with viruses such as flu during pregnancy are linked with higher rates of autism, as well as brain conditions such as schizophrenia and attention deficit hyperactivity disorder. The explanation is unclear, but work in animals suggests an infection increases the amount of inflammatory chemicals in the bloodstream, which could affect the developing fetus’s brain.

To better understand the potential impact of covid-19 during pregnancy, Perlis’s team compared the records of 7550 women who didn’t test positive for the infection while pregnant with the 222 women who did, all of whom attended six hospitals in Massachusetts for various reasons in 2020.

The team looked at whether any of the babies had been diagnosed with delays in speech and physical development by their family doctors or paediatricians by the time they turned 1.

Once the team adjusted the data to take into account risk factors such as race and whether the babies were born prematurely, the babies of the infected women had a 1.9-fold higher risk of delays. Prematurity is relevant because covid-19 raises the risk of a pregnant person giving birth prematurely and premature babies may be delayed in reaching milestones.

In 2020, the original covid-19 strain that emerged from Wuhan in China was circulating worldwide. The team doesn’t know if being infected by a different variant or being vaccinated against covid-19 would affect the results.

Women who know they caught covid-19 may be more anxious about their baby’s development, which may prompt them to seek medical help if they suspect any delays, says Chris Gale at Imperial College London.

“This study shows the importance of following up babies, but it’s too early to say if there’s definitely an impact,” he says.

Regardless of the results, anyone who is pregnant or planning to conceive should get vaccinated against covid-19, says Gale. “Pregnant women are clearly an at-risk group, for their health and for the health of their babies.”