Contracting COVID-19 while pregnant could lead to a higher risk of obesity for the child: study

A small study is presenting evidence suggesting a strange possible outcome of a COVID-19 infection during pregnancy: higher risk of obesity for the child.

Specifically, researchers observed a pattern of U.S. women who had COVID-19 at some point during their pregnancy and gave birth to infants with a lower initial weight, who then gained weight much faster than other babies.

“Our findings suggest that children exposed in utero to maternal COVID-19 have an altered growth pattern in early life that may increase their risk of obesity, diabetes and cardiovascular disease over time,” Lindsay T. Fourman, a doctor with Massachusetts General Hospital and one of the study authors, said in a press release. “There is still a lot of research needed to understand the effects of COVID-19 on pregnant women and their children.”

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While previous studies have looked into the impacts of COVID-19 on pregnant people and found that they are more likely to experience severe disease compared to non-pregnant people with COVID-19, the impacts of the virus on the infant is still largely unknown.

In order to assess the impacts of COVID-19 during pregnancy on the infants, researchers looked at just under 280 infants who were born during the pandemic prior to June 2021 and had received care at the Massachusetts General Hospital.

Infants were not included in the study if their mother had received a vaccination during pregnancy or had unclear vaccination status.

Around 150 infants in the study had mothers who contracted COVID-19 at some point in their pregnancy, while around 130 infants were carried by mothers with a COVID-free pregnancy. All were at least 12 months of age when researchers carried out data collection and analysis.

Most of the mothers in the study who had contracted COVID-19 had a mild disease in their third trimester.

Exposure to COVID-19 in-utero was associated with a lower birth weight even when researchers controlled for aspects such as maternal age, ethnicity and socioeconomic factors such as insurance status. The same was true for the infants’ patterns of weight gain over the first year of their lives, with in-utero exposure to the virus associated with a different pattern than the control group, along with more weight gain.

The absolute difference in the weight gain between infants with in-utero exposure to the virus and those without was small, but researchers say a trend was still clear.

It’s unclear what impact this early weight gain will have for this cohort of children and whether it will be consequential or not, although the study noted that “lower birth weight and accelerated postnatal weight gain are risk factors for cardiometabolic disease.”

It’s important to note that this research is constrained by the short amount of time that has passed since the first relevant study group was born, meaning that it’s also going to be unclear for a while whether this trend continues into childhood or whether larger studies will find the same results.

But as countries leave behind public health measures, more pregnant people are being exposed to COVID-19, leaving unknown impacts that call for further monitoring and research in the future.

Pregnant women made up around nine per cent of reproductive-aged women with SARS-CoV-2 infections in the U.S., according to a 2020 study referenced by researchers.

Although data is limited across Canada, there had been at least 9,000 instances of a pregnant person contracting COVID-19 in Canada as of January 2022, according to a tracker run by the University of British Columbia.

These figures together suggest that thousands of babies worldwide may be born to parents who had the virus at some point during pregnancy.

“Our findings emphasize the importance of long-term follow-up of children exposed in utero to maternal COVID-19 infection, as well as widespread implementation of COVID-19 prevention strategies among pregnant individuals,” Andrea G. Edlow, a doctor with the Massachusetts General Hospital and another study author, said in the release. “Larger studies with longer follow-up duration are needed to confirm these associations.”