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Risk of Severe COVID-19 Symptoms Remains Throughout Pregnancy, UTSW Study Finds

UT Southwestern researchers found no increased risk of adverse outcomes among babies or mothers when mothers were infected with COVID-19.
Photo credit: Getty Images
covid pregnancy

UT Southwestern researchers found no increased risk of adverse outcomes among babies or mothers when mothers were infected with COVID-19. Photo credit: Getty Images

DALLAS – A UT Southwestern study of more than 1,300 pregnant women diagnosed with COVID-19 found that just 1 in 10 developed moderate, severe, or critical illness and that COVID-19 symptoms and severity were similar across all trimesters.   

The findings, which encompass one of the largest single-institution studies on COVID-19 infection during pregnancy, appear in the November issue of the American Journal of Obstetrics and Gynecology MFM.

Rachel Schell, M.D.

Rachel Schell, M.D.

“In the rapidly evolving landscape of the COVID-19 pandemic, this study provides information regarding the natural course of COVID-19 infection in pregnancy,” said Rachel Schell, M.D., Assistant Instructor in Obstetrics and Gynecology at UT Southwestern and first author of the paper. “This may be useful for clinicians to effectively counsel patients and direct care.”

Throughout the pandemic, an estimated 182,000 pregnant women have been diagnosed with COVID-19 in the U.S. Studies have shown that pregnant patients are at an increased risk of severe and critical disease compared with nonpregnant females of similar ages. However, little was known about how the timing of infection during pregnancy might affect these risks.

In the UTSW study, Dr. Schell and colleagues collected data on 1,326 patients who delivered babies at Parkland Health between March 2020 and September 2021 and tested positive for COVID-19 on polymerase chain reaction (PCR) tests at any point during their pregnancies. Of these patients, 103 (8%) tested positive during the first trimester, 355 (27%) tested positive in the second trimester, and 868 (65%) during the third trimester.

When the researchers studied how often the women were admitted to the hospital for COVID-19, the severity of their symptoms, and how their symptoms progressed, they found no statistically significant difference between pregnant patients infected in each trimester. Overall, about 10% of pregnant COVID-19 patients who were asymptomatic went on to develop symptoms, and about 10% of infected patients had symptoms that could be categorized as moderate, severe, or critical.

“Given that patients in all trimesters of pregnancy are susceptible to infection and severe respiratory illness from COVID-19, these findings add urgency to the need for vaccination of all pregnant individuals,” said Dr. Schell. 

Researchers also found no increased risk of adverse outcomes — among either babies or mothers — when mothers were infected with COVID-19. The rates of poor outcomes, including stillbirths, were similar to those in the general population and did not vary by trimester of infection. 

Previous studies focusing on hospitalized pregnant COVID-19 patients suggest that poor outcomes could be correlated with more serious cases. In the UTSW study, the researchers were not able to analyze potential correlations between outcomes and severity of COVID-19 symptoms.

Other UTSW researchers who contributed to this study include Devin A. Macias, W. Holt Garner, Alesha M. White, Donald D. McIntire, Jessica Pruszynski, and Emily H. Adhikari.

The research was supported in part by a pilot project grant via the Seldin Scholars from the UT Southwestern Department of Internal Medicine. Additional funding was provided by the Division of Maternal-Fetal MedicineDepartment of Obstetrics and Gynecology at UTSW.

About Parkland Health

Parkland Health is one of the largest public hospital systems in the country. Premier services at the state-of-the-art Parkland Memorial Hospital include the Level I Rees-Jones Trauma Center, the only burn center in North Texas verified by the American Burn Association for adult and pediatric patients, and a Level III Neonatal Intensive Care Unit. The system also includes two on-campus outpatient clinics – the Ron J. Anderson, MD Clinic and the Moody Outpatient Center, as well as more than 30 community-based clinics and numerous outreach and education programs. By cultivating its diversity, inclusion and health equity efforts, Parkland enriches the health and wellness of the communities it serves. For more information, visit