On November 2, 2020, this report was posted online as an MMWR Early Release. Pregnant women with coronavirus disease 2019 (COVID-19) are at increased risk for severe illness and might be at risk for preterm birth ( 1 – 3 ). The full impact of infection with SARS-CoV-2, the virus that causes COVID-19, in pregnancy is unknown. Public health jurisdictions report information, including pregnancy status, on confirmed and probable COVID-19 cases to CDC through the National Notifiable Diseases Surveillance System.* Through the Surveillance for Emerging Threats to Mothers and Babies Network (SET-NET), 16 jurisdictions collected supplementary information on pregnancy and infant outcomes among 5,252 women with laboratory-confirmed SARS-CoV-2 infection reported during March 29–October 14, 2020. Among 3,912 live births with known gestational age, 12.9% were preterm ( 0.1) for all. † Inclusive of women reported as symptomatic on the COVID-19 case report form (https://www.cdc.gov/coronavirus/2019-ncov/php/reporting-pui.html) or who had any symptoms reported on the COVID-19 case report form regardless of completion of the symptom status variable. § Pregnancy outcomes include 79 sets of twins and one set of triplets; therefore, number exceeds the number of women. ¶ Among term (≥37 weeks) infants only, reason for admission could include need for isolation of an otherwise asymptomatic infant based on possible SARS-CoV-2 exposure. ** Includes congenital heart defects (seven), cleft lip and/or palate (four), chromosomal abnormalities (four), genitourinary (four), gastrointestinal (two), cerebral cysts (one), talipes equinovarus (one), developmental dysplasia of the hip (one), supernumerary digits (one) and five had no birth defects specified. Total exceeds 28 because some infants had multiple birth defects reported. Information on infant SARS-CoV-2 testing was reported from 13 jurisdictions; among 923 infants with information, 313 (33.9%) were not tested. Among 610 (21.3%) infants for whom molecular test results were reported, 16 (2.6%) results were positive (Table 3), including 14 for whom the timing of the mothers’ infection during pregnancy was reported. The percent positivity was 4.3% (14 of 328) among infants born to women with documentation of infection identified ≤14 days before delivery and 0% (0 of 84) among those born to women with documentation of infection identified >14 days before delivery. TABLE 3 Characteristics of laboratory-confirmed infection among infants born to pregnant women with laboratory-confirmed SARS-CoV-2 infection — SET-NET, 13* jurisdictions, March 29–October 14, 2020 Characteristic No. of infants (%)[Total no. of infants with available information] Total Not tested or missing data† RT-PCR positive results RT-PCR negative results N = 2,869 (100.0) N = 2,259 (78.7) N = 16 (0.6)§ N = 594 (20.7) Maternal symptom status [1,871] [1,475] [13] [383] Asymptomatic 231 (12.3) 127 (8.6) 4 (30.8) 100 (26.1) Symptomatic 1,640 (87.7) 1,348 (91.4) 9 (69.2) 283 (73.9) Timing of maternal infection¶ [1,851] [1,440] [14] [398] ≤7 days before delivery 740 (40.0) 456 (31.7) 11 (84.6) 273 (68.6) 8–10 days before delivery 77 (4.2) 56 (3.9) 1 (7.7) 20 (5.0) >10 days before delivery 1,034 (55.9) 928 (64.4) 1 (7.7) 105 (26.4) Median (IQR) days from mother’s first positive test to delivery 17 (2–53) 28 (3–63) 1 (0–4) 2 (0–12) Maximum days from mother’s first positive test to delivery 191 191 12 132 Gestational age at birth [2,692] [2,085] [16] [591] Term (≥37 wks) 2,349 (87.3) 1,849 (88.7) 8 (50) 492 (83.2) Late preterm (34–36 wks) 237 (8.8) 168 (8.1) 3 (18.8) 66 (11.2) Moderate to very preterm ( 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. Summary What is already known about this topic? Pregnant women with SARS-CoV-2 infection are at increased risk for severe illness compared with nonpregnant women. Adverse pregnancy outcomes such as preterm birth and pregnancy loss have been reported. What is added by this report? Among 3,912 infants with known gestational age born to women with SARS-CoV-2 infection, 12.9% were preterm (<37 weeks), higher than a national estimate of 10.2%. Among 610 (21.3%) infants with testing results, 2.6% had positive SARS-CoV-2 results, primarily those born to women with infection at delivery. What are the implications for public health practice? These findings can inform clinical practice, public health practice, and policy. It is important that providers counsel pregnant women on measures to prevent SARS-CoV-2 infection.
