Two New CDC MMWR Studies Highlight Important Developments Regarding Impact of COVID-19 During Pregnancy

The following has been shared by the CDC National Center on Birth Defects and Developmental Disabilities for our members' information. Please share with colleagues as you see fit.


Two new CDC MMWR studies, published this week, that highlight important developments regarding the impact of COVID-19 during pregnancy on both pregnant women and their infants. The findings from both studies underscore the need for continued monitoring of illness severity and evaluating birth and infant outcomes among pregnant women with COVID-19. Details of both studies are below.

The study on birth and infant outcomes was possible because of CDC’s Surveillance for Emerging Threats to Mothers and Babies Network (SET-NET), which is housed in the Division of Birth Defects and Infant Disorders. SET-NET is a surveillance approach that detects the effects of new health threats on pregnant women and their babies by collecting data from pregnancy through early childhood. SET-NET was established in FY 2019 and was able to quickly pivot to address COVID-19 and scale up with support from one-time supplemental and emergency appropriations.  

Key questions remain about the full impact of COVID-19 on pregnancy, including possible transmission to the infant. SET-NET will continue to collect data on the effects of COVID-19 on pregnant women and infants up to 6 months of age to guide clinical and public health practice. 


MMWR “Update: Characteristics of Symptomatic Women of Reproductive Age with Laboratory-Confirmed SARS-CoV-2 Infection by Pregnancy Status — United States, January 22–October 3, 2020”

The first study found that pregnant women with COVID-19 are at increased risk for severe illness, compared with non-pregnant women with COVID-19. Markers for severe illness included admission to an intensive care unit, receipt of invasive ventilation, receipt of extracorporeal membrane oxygenation (or ECMO, an advanced life support technique used for patients with life-threatening heart and/or lung problems), and death. Although the absolute risks of severe illness are low overall, pregnant women are at increased risk compared with nonpregnant women with COVID-19, and risk of severe outcomes were highest among women in the oldest age group (ages 35 – 44). Hispanic or Black women were found to be disproportionately affected by COVID-19 during pregnancy. Further, pregnant Hispanic women were more likely to die compared to nonpregnant women relative to other subgroups, and non-Hispanic Black women were disproportionately represented in the total number of deaths among women with COVID-19, regardless of pregnancy status. 

MMWR “Birth and Infant Outcomes Following Laboratory-Confirmed SARS-CoV-2 Infection in Pregnancy — SET-NET, 16 Jurisdictions, March 29–October 14, 2020”

The second study found that pregnant women with COVID-19 may be at increased risk of having a preterm infant (born before 37 weeks), which may lead to serious health problems for the infant.  Infants born to mothers with COVID-19 during pregnancy were rarely found to have positive COVID-19 test results, and those who did have a positive test result were primarily born to mothers who had COVID-19 within one week of delivery. Pregnant women and their families should continue to follow key mitigation measures to reduce their risk of becoming ill with COVID-19.


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