14 January 2022 - - People who contracted COVID-19 while pregnant were more likely to have poor birth outcomes including preterm birth, small for gestational age, low birth weight, and stillbirth, according to the results of an Institute for Systems Biology-led study.

The poor outcomes of preterm birth and stillbirth were observed primarily with those infected with SARS-CoV-2 during the first or second trimester, whereas increased rates of small for gestational age were driven largely by third trimester infection.

An Institute for Systems Biology-led study examined the electronic health records of more than 18,000 people with SARS-CoV-2 tests during pregnancy.

Researchers compared outcomes of unvaccinated people with a positive test during pregnancy 882 in total to those who tested negative.

The people in the study had mild or moderate SARS-CoV-2 infections. Severity of maternal COVID-19 infection was not correlated with gestational age at delivery.

Additionally, poor birth outcomes were present even if maternal COVID-19 didn't result in severe respiratory problems during infection.

The findings were published in the journal The Lancet Digital Health and are among the first that account for the trimester of SARS-CoV-2 infection on birth outcomes. 

People in the SARS-CoV-2-positive cohort were more likely to have Hispanic ethnicity, race other than Asian or White, Medicaid insurance, lower age, higher BMI, lower education attainment, and other factors known to be associated with negative birth outcomes.

To account for this and to make a true apples-to-apples comparison, researchers used a statistical matching technique that controlled for the confounding variables.

The study was conducted before COVID-19 vaccines were widely available in the United States. There is an opportunity for future studies to examine whether vaccination helps to prevent negative birth outcomes in breakthrough cases.

This research project was a collaboration between ISB and Providence.

Institute for Systems Biology is a Seattle-based non-profit biomedical research organization. We focus on some of the most pressing issues in human health, including aging, autoimmune diseases, brain health, cancer, and many infectious diseases.

ISB is an affiliate of Providence, one of the nation's largest not-for-profit health care systems.