Birth and Infant Outcomes Following Laboratory-Confirmed SARS-CoV-2 Infection in Pregnancy

SET-NET, 16 Jurisdictions, March 29-October 14, 2020

Kate R. Woodworth, MD; Emily O'Malley Olsen, PhD; Varsha Neelam, MPH; Elizabeth L. Lewis, MPH; Romeo R. Galang, MD; Titilope Oduyebo, MD; Kathryn Aveni, MPH; Mahsa M. Yazdy, PhD; Elizabeth Harvey, PhD; Nicole D. Longcore, MPH; Jerusha Barton, MPH; Chris Fussman, MS; Samantha Siebman, MPH; Mamie Lush, MA; Paul H. Patrick, MPH; Umme-Aiman Halai, MD; Miguel Valencia-Prado, MD; Lauren Orkis, DrPH; Similoluwa Sowunmi, MPH; Levi Schlosser, MPH; Salma Khuwaja, MD; Jennifer S. Read, MD; Aron J. Hall, DVM; Dana Meaney-Delman, MD; Sascha R. Ellington, PhD; Suzanne M. Gilboa, PhD; Van T. Tong, MPH


Morbidity and Mortality Weekly Report. 2020;69(44):1635-1640. 

In This Article


In this analysis of COVID-19 SET-NET data from 16 jurisdictions, the proportion of preterm live births among women with SARS-CoV-2 infection during pregnancy (12.9%) was higher than that in the general population in 2019 (10.2%),[4] suggesting that pregnant women with SARS-CoV-2 infection might be at risk for preterm delivery. These data are preliminary and describe primarily women with second and third trimester infection, and findings are subject to change pending completion of pregnancy for all women in the cohort and enhanced efforts to improve reporting of gestational age. This finding is consistent with other CDC reports describing higher proportions of preterm births among women hospitalized at the time of SARS-CoV-2 infection[2,3] and includes outcomes for women hospitalized as well as those not hospitalized at the time of infection (representing a population including persons with less severe illness). Increased frequency of preterm births was also described in a living, systematic review of SARS-CoV-2 infection in pregnancy.[5] In contrast, a prospective cohort study of 253 infants found no difference in proportion of preterm birth or infant ICU admission between those born to women with positive SARS-CoV-2 test results and those born to women with suspected SARS-CoV-2 but negative test results,[6] although the difference in findings between these two studies might be attributable to differences in case ascertainment, methodology, data collection, and sample size. Studies comparing pregnant women with and without COVID-19 are needed to assess the actual risk of preterm birth.

Non-Hispanic Black and Hispanic women were disproportionally represented in this surveillance cohort. Racial and ethnic disparities exist for maternal morbidity, mortality, and adverse birth outcomes,[7–9] and the higher incidence and increased severity of COVID-19 among women of color might widen these disparities.*** Further surveillance efforts, including reporting by additional jurisdictions to improve representativeness, and careful analysis of outcomes by race and ethnicity, will permit more direct and targeted public health action.

Information regarding the frequency and severity of perinatal (potentially including in utero, peripartum, and postnatal) infection is lacking. The American Academy of Pediatrics and CDC recommend testing all infants born to mothers with suspected or confirmed COVID-19.††† However, testing results were infrequently reported in this cohort. Perinatal infection was uncommon (2.6%) among infants known to have been tested for SARS-CoV-2 and occurred primarily among infants born to women with infection within 1 week of delivery. Among the infants with positive test results, one half were born preterm, which might reflect higher rates of screening in the ICU. These findings also support the growing evidence that although severe COVID-19 does occur in neonates the majority of term neonates experience asymptomatic infection or mild disease§§§; however, information on long term outcomes among exposed infants is unknown.

The findings of this report are subject to at least six limitations. First, completeness of variables, particularly those ascertained through interviews or medical record abstraction, varied by jurisdiction. Statistical comparisons by maternal symptom status should be interpreted with caution given that symptom status was missing for a substantial proportion. Ongoing efforts to increase matching reported information with existing data sources has improved case ascertainment and completion of critical data elements. Testing and reporting might be more frequent among women with more severe illness or adverse birth outcomes. Second, these data are not nationally representative and include a higher frequency of Hispanic women compared with all women of reproductive age in national case surveillance data.[1] Third, ascertainment of pregnancy loss depends on linkages to existing data sources (e.g., fetal death reporting), and potential underascertainment of this outcome limits comparison with national estimates. Fourth, few women with first trimester infection and completed pregnancy have been reported to date, limiting ability to evaluate adverse outcomes that might be more likely to be affected by infection earlier in pregnancy, such as birth defects. Fifth, risk factors (e.g., history of previous preterm birth) and clinical details associated with preterm delivery (e.g., spontaneous versus iatrogenic for maternal or fetal indications) were not assessed. Finally, a large proportion of infants had no testing reported. Positive SARS-CoV-2 RT-PCR results are reportable, and this percent positivity is likely an overestimate if negative testing was less often reported. Despite these limitations, this report describes a large population-based cohort with completed pregnancy outcomes and some infant testing.

These data can help to inform and counsel persons who acquire COVID-19 during pregnancy about potential risk to their pregnancy and infants; however, the risks associated with infection early in pregnancy and long-term infant outcomes remain unclear. SET-NET will continue to follow pregnancies affected by SARS-CoV-2 through completion of pregnancy and infants until age 6 months to guide clinical and public health practice. Longer-term investigation into solutions to alleviate underlying inequities in social determinants of health associated with disparities in maternal morbidity, mortality, and adverse pregnancy outcomes, and effectively addressing these inequities, could reduce the prevalence of conditions and experiences that might amplify risks from COVID-19. It is important that health care providers counsel pregnant women that SARS-CoV-2 infection might increase the risk for preterm birth and that infants born to women with infection identified >14 days before delivery might have a lower risk of having test results positive to SARS-CoV-2. Pregnant women and their household members should follow recommended infection prevention measures, including wearing a mask, social distancing, and frequent handwashing when going out or interacting with others. In addition, pregnant women should continue measures to ensure their general health including staying up to date with annual influenza vaccination and continuing prenatal care appointments.