COVID-19 during pregnancy can lead to changes in infant birth weight and weight gain during the first year of life.

COVID-19 during pregnancy can lead to changes in infant birth weight and weight gain during the first year of life.

What you need to know

From January to June of 2020, about 9 percent of reproductive-aged women who had COVID-19 were pregnant. But very little is understood about how in-utero exposure to SARS-CoV-2, the virus that causes COVID-19, can affect an infant’s health.

In a small study supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), researchers found that babies exposed to COVID-19 in utero showed differences in weight gain over their first year of life. These differences may be an early sign of future health complications.

What did the researchers do?

Using Mass General Brigham’s COVID-19 Pregnancy Biorepository, researchers studied electronic health records to measure babies’ weight from birth to 1 year of age. They compared data from 149 babies who were exposed to COVID-19 in utero with the data for 127 babies who were not exposed.

The researchers found that infants exposed to COVID-19 during pregnancy weighed about 30 percent less at birth than those with no exposure. However, over the course of their first year, babies exposed to COVID-19 showed a nearly 53 percent greater weight gain compared with babies who were not exposed. The researchers suggested that infection with the SARS-CoV-2 virus may have prevented these babies from growing as much in the womb. The accelerated weight gain over their first year of life would then reflect the body trying to “catch up” after birth.

Why is this research important?

The researchers cautioned that such “catch-up” weight gain early in life can be associated with a greater risk for obesity and conditions like hypertension or diabetes in adulthood. Similar trends have been seen in infants exposed to other infections in utero or chronic conditions, even when the infection was not transmitted. The study highlights the importance of protective measures against COVID-19 for pregnant people, including masking and vaccination.

Where can I go to learn more?

Children born to women with COVID-19 could be at risk for heart disease, diabetes later in life

  • Infants weighed less at birth and grew faster in their first year than infants born to mothers without COVID-19.

COVID-19 During Pregnancy and Postpartum

  • NICHD shares more research on the effects of COVID-19 infection and disease during pregnancy, postpartum, during lactation, and in newborns.

COVID-19 Vaccination During Pregnancy Likely Benefits Moms and Babies

  • NIH shares research supporting the safety and efficacy of vaccinations for both mothers and their unborn babies.


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Fourman, L. T., Pan, C. S., Zheng, I., Gerard, M. E., Sheehab, A., Lee, H., Stanley, T. L., & Grinspoon, S. K. (2020). Association of in utero HIV exposure with obesity and reactive airway disease in HIV-negative adolescents and young adults. Journal of Acquired Immune Deficiency Syndromes, 83(2), 126-134.

Ockene, M. W., Russo, S. C., Lee, H., Monthé-Drèze, C., Stanley, T. L., Ma, I. L., Toribio, M., Shook, L. L., Grinspoon, S. K., Edlow, A. G., & Fourman, L. T. (2023). Accelerated longitudinal weight gain among infants with in utero COVID-19 exposure. The Journal of Clinical Endocrinology & Metabolism, dgad130.


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Page last updated: June 8, 2023