Arnold School researchers associated with the South Carolina Smart State Center for Healthcare Quality have published new research in the Annals of Epidemiology regarding the impact of COVID-19 infections on women who were pregnant before and during the pandemic. Led by Maria Sevoyan, a post-doctoral fellow in the Department of Epidemiology and Biostatistics, the team found that mothers who became pregnant after the start of the pandemic, those who experienced moderate-to-severe infections during pregnancy, and those who had infections during the third trimester were more likely to have adverse outcomes (e.g., low birth weight, preterm birth, NICU admission).

“Due to their altered immune system, pregnant women are particularly vulnerable to severe infections,” says Xiaoming Li, professor of health promotion, education, and behavior and director for the Center for Healthcare Quality. “The number of pregnant women who contracted SARS-CoV-2 during the pandemic raised concerns about the possible impacts on perinatal outcomes.”

While some research has shown an unexpected decrease in preterm birth early on in the pandemic, this may be due to mitigation and prevention measures and does not tell the whole story of COVID-19’s effects on pregnancy and birth. Other reports have demonstrated an increased risk of low birthweight and NICU admissions among women who experienced infections during their pregnancies.

With this study, the researchers aimed to expand this knowledge base to include other perinatal outcomes (e.g., breastfeeding initiation, small-for-gestational-age), consider the timing of pregnancies relative to the pandemic and severity of infection, and analyze data from a much larger group compared to previous research. The team analyzed data from electronic health records, including hospital data and the state’s COVID-19 testing registry, to look at the health outcomes of nearly 200,000 births that occurred between 2018 and 2021 in South Carolina.

They found that the infants of women who were pregnant before the pandemic began but who gave birth during the pandemic were less likely to be preterm or low birthweight (likely due to mitigation measures). However, as the pandemic progressed, women whose entire pregnancies occurred after March 2020 were more likely than any other group to experience preterm birth and NICU admissions. They were also less likely to initiate breastfeeding. In addition, moderate-to-severe infections and those that took place during the third trimester were also associated with an increased risk of adverse perinatal outcomes.

“This study revealed that women who became pregnant after the start of the pandemic were more likely to experience preterm birth, low birthweight and the need for NICU services—regardless of whether they had COVID-19 infections during their pregnancy—and that women with more severe infections and who experienced them during the latter stages of pregnancy were also at higher risk,” says Jihong Liu, professor of epidemiology and biostatistics and the corresponding author of the paper.

“These findings suggest that it is important to consider both the infection—including the timing and severity—and other pandemic-related factors, such as mitigation measures and timing of pregnancy, when working to optimize perinatal outcomes.”

Study co-authors include Maria Sevoyan (Epidemiology and Biostatistics), Jihong Liu (Epidemiology and Biostatistics), Yi-Wen Shih (Health Services Policy and Management), Peiyin Hung (Health Services Policy and Management), Jiajia Zhang (Epidemiology and Biostatistics), and Xiaoming Li (Health Promotion, Education, and Behavior).