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

Our take —

Obstetric and infant outcome data for pregnant women with SARS-CoV-2 infection in 16 jurisdictions in the United States between March and October 2020 indicated that 12.9% of infants were born preterm, and that there were no statistically significant differences in frequency of preterm birth by mother’s symptom status. Though neonatal testing for SARS-CoV-2 was found to be incomplete, seropositivity was 2.6% among those with results, and these data are consistent with evidence from many studies that have found neonatal infections to be extremely rare. These data should be interpreted as preliminary, as there are missing data for pregnancy outcomes, symptom status of the mother and known gestational age.

Study design


Study population and setting

Between March 29 and October 14th 2020, information on pregnancy and infant outcomes was collected through the Surveillance for Emerging Threats and Babies Network (SET-NET) for 5252 pregnant women with confirmed SARS-CoV-2 infection. These women resided in 16 jurisdictions across the United States, and among them, pregnancy outcomes were reported for 4442 (84.6%). Infant perinatal outcomes were reported and statistically significant differences between those born to mothers with symptomatic and asymptomatic infection were examined.

Summary of Main Findings

A majority of women with known pregnancy outcomes were infected with SARS-CoV-2 in the third trimester (2794/4442). An underlying condition was reported for 1567 of 4442 women (e.g. pre-pregnancy obesity, chronic hypertension, diabetes). In total there were 4495 (99.3%) live births and 32 (0.7%) pregnancy losses. Among infants with known gestational age 12.9% (506/3912) were preterm, and there were no statistically significant differences in the prevalence of preterm birth by maternal symptom status. Among those infants with SARS-CoV-2 testing information (n=923), close to one third were not tested (313/923). For those infants who were tested during the perinatal period (n=610), 16 (2.6%) were positive. Half of the infants with a positive test result (8/16) were born preterm and admitted to a neonatal ICU.

Study Strengths

Collection of diagnosis data through a surveillance network among pregnant women and follow-up to prospectively assess infant outcomes is a study strength.


There is a substantial amount of missing data for the different outcomes (e.g. pregnancy outcomes, underlying conditions, known gestational age, infant testing), which is common in surveillance datasets. Due to missing data at these different levels, it is difficult to assess who these results apply to; there is a possibility that those in the sample may not be representative of the original target population. Additionally, testing for neonatal immunoglobulin M, placental tissue, or amniotic fluid was not reported and therefore the study was unable to distinguish between intra- and post-partum infection. SARS-CoV-2 infection was primarily reported in the third trimester, and further research is needed on infection in early pregnancy and long-term outcomes of infants. Finally, there is no comparison group of similar pregnant women without SARS-CoV-2 infection, and data on risk factors for preterm birth were not described for the sample; therefore, the ability to compare preterm birth outcomes with other samples is limited.

Value added

This report provides descriptive data on birth outcomes among women with SARS-CoV-2 infection during pregnancy, assesses perinatal infections among infants, and examines differences by symptom status of the mother.

This review was posted on: 9 February 2021