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

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 (<37 weeks), higher than the reported 10.2% among the general U.S. population in 2019 (4). Among 610 infants (21.3%) with reported SARS-CoV-2 test results, perinatal infection was infrequent (2.6%) and occurred primarily among infants whose mother had SARS-CoV-2 infection identified within 1 week of delivery. Because the majority of pregnant women with COVID-19 reported thus far experienced infection in the third trimester, ongoing surveillance is needed to assess effects of infections in early pregnancy, as well the longer-term outcomes of exposed infants. These findings can inform neonatal testing recommendations, clinical practice, and public health action and can be used by health care providers to counsel pregnant women on the risks of SARS-CoV-2 infection, including preterm births. 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 or if there is a person within the household who has had exposure to COVID-19.^†

SET-NET conducts longitudinal surveillance of pregnant women and their infants to understand the effects of emerging and reemerging threats.^§ Supplementary pregnancy-related information is reported for women with SARS-CoV-2 infection (based on detection of SARS-CoV-2 in a clinical specimen by molecular amplification detection testing^¶) during pregnancy through the day of delivery. As of October 14, 2020, 16 jurisdictions** have contributed data. Pregnancy status was ascertained through routine COVID-19 case surveillance or through matching of reported cases with other sources (e.g., vital records, administrative data) to identify or confirm pregnancy status. Data were abstracted using standard forms^††; sources include routine public health investigations, vital records, laboratory reports, and medical records. Chi-squared tests were performed to test for statistically significant (p<0.05) differences in proportion of outcomes between women reported to have symptomatic infection and those reported to have asymptomatic infection using SAS (version 9.4; SAS Institute). This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.^§§

Jurisdictions reported 5,252 pregnant women with SARS-CoV-2 infection. Among these women, 309 (5.9%) were presumed to have ongoing pregnancies (no outcome reported and not past their estimated due date plus 90 days for reporting lag), and 501 (9.5%) did not have pregnancy outcomes reported and were either missing an estimated due date or presumed lost to follow-up. This report focuses on the 4,442 women with known pregnancy outcomes (84.6% of 5,252 women).

The median age of women was 28.9 years, and 46.0% were Hispanic or Latina (Hispanic) ethnicity (Table 1). At least one underlying medical condition was reported for 1,564 (45.1%) women, with prepregnancy obesity (body mass index ≥30 kg/m²) (35.1%) being the most commonly reported. Most (84.4%) women had infection identified in the third trimester (based on date of first positive test result or symptom onset). Symptom status was known for 2,691 (60.6%) women, 376 (14.0%) of whom were reported to be asymptomatic.

Among 4,527 fetuses and infants, the outcomes comprised 4,495 (99.3%) live births (including 79 sets of twins and one set of triplets), 12 (0.3%) pregnancy losses at <20 weeks’ gestation, and 20 (0.4%) losses at ≥20 weeks’ gestation (Table 2). Among 3,912 infants with reported gestational age, 506 (12.9%) were preterm, including 149 (3.8%) at <34 weeks and 357 (9.1%) at 34–37 weeks. Frequency of preterm birth did not differ by maternal symptom status (p = 0.62), including among women hospitalized at the time of infection (p = 0.81, Fisher’s exact test). Among 3,486 (77.6%) live births with weight, gestational age, and sex reported, 198 (5.7%) were small for gestational age.^¶¶ Twenty-eight (0.6%) infants were reported to have any birth defect; among 23 infants for whom timing of maternal SARS-CoV-2 infection during pregnancy was known, 17 (74%) were born to mothers with infection identified in the third trimester. Nine (0.2%) in-hospital neonatal deaths were reported. Among term infants (≥37 weeks’ gestation), 9.3% were admitted to an intensive care unit (ICU); however, reason for admission was often missing.

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.

Eight of the infants with positive test results were born preterm (26–35 weeks); all were admitted to a neonatal ICU (NICU) without indications reported. Among the eight term infants with positive test results, one was admitted to a NICU for fever and receipt of supplemental oxygen, one had no information on NICU admission, and the remaining six were not admitted to a NICU. No neonatal immunoglobulin M or pregnancy-related specimen (e.g., placental tissue or amniotic fluid) testing was reported; thus, routes of transmission (in utero, peripartum, or postnatal) could not be assessed.

Acknowledgments

State, local, and territorial health department personnel; U.S. clinical, public health, and emergency response staff members; CDC Epidemiology Studies Task Force, CDC Data Analytics and Modeling Task Force; Olga Barer, Valorie Eckert, Richard Olney, Barbara Warmerdam, California Department of Public Health; Cynthia Carpentieri, Chickasaw Nation Industries, Georgia Department of Public Health; Reynaldo J. Pérez Alicea, Camille Delgado-López, Mariam Marcano Huertas, Marangeli Olan-Martinez, Glorimar Melendez-Rosario, Leishla Nieves-Ferrer, Hilcon Agosto Rosa, G2S Corporation, Puerto Rico Department of Health; J. Michael Bryan, Amanda Feldpausch, Skip Frick, Cristina Meza, Rochelle Minter, Victoria Sanon, Anam Syed, Teri’ Willabus, Georgia Department of Public Health; Ifrah Chaudhary, Patrick Nwachukwu, Houston Health Department; Emily Barnes, Caleb Lyu, Nina Mykhaylov, Van Ngo, Lisa V. Smith, Los Angeles County Department of Public Health; Catherine Brown, Eirini Nestoridi, Hanna Shephard; Massachusetts Department of Public Health; Alexandra Gold, Michigan Department of Health and Human Services; Emily Holodnick, Minnesota Department of Health; Tyler Faulkner, Ericka Fuchs, Samir Koirala, Shannon Lawrence, Celeste Liana, Robin M. Williams, Nebraska Department of Health and Human Services; Joy Rende, New Jersey Department of Health; Zahra S. Alaali, Dierdre Depew, Elizabeth Dufort, Clair McGarry, Cori J. Rice, Amy Robbins, Jamie N. Sommer, Nadia Thomas, New York State Department of Health; Megan Meldrum, NYS Immunization Information System, New York State Department of Health; Bethany Reynolds, Pennsylvania Department of Health; Stephany I. Perez-Gonzalez, Puerto Rico Department of Health; Lindsey Sizemore, Heather Wingate, Tennessee Department of Health.

Corresponding author: Kate Woodworth, eocevent397@cdc.gov.

¹CDC COVID-19 Response; ²New Jersey Department of Health; ³Massachusetts Department of Public Health; ⁴Tennessee Department of Health; ⁵New York State Department of Health; ⁶Georgia Department of Public Health; ⁷Michigan Department of Health and Human Services; ⁸Minnesota Department of Health; ⁹Nebraska Department of Health and Human Services; ¹⁰Oklahoma State Health Department; ¹¹Los Angeles County Department of Public Health; ¹²Puerto Rico Department of Health; ¹³Pennsylvania Department of Health; ¹⁴California Department of Public Health; ¹⁵North Dakota Department of Health; ¹⁶Houston Health Department; ¹⁷Vermont Department of Health.

References

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Abbreviations: BMI = body mass index; COVID-19 = coronavirus disease 2019.
*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.
^† Latest known insurance during pregnancy or at delivery.
^§ Includes all listed for all women, and gestational diabetes mellitus and pregnancy induced hypertension for women with infection identified in the third trimester. Pregnancy itself is not considered an underlying condition.
^¶ Includes either type 1 or type 2 diabetes, does not include gestational diabetes.
** Other conditions include neurologic conditions or disabilities, chronic renal disease, chronic liver disease, psychiatric disorders, and autoimmune disorders.
^†† Among women with SARS-CoV-2 infection in third trimester.
^§§ Calculated as either date of specimen collection for first positive test, or symptom onset if exact date of specimen collection was missing.

Abbreviations: ICU = intensive care unit; IQR = Interquartile range; RT-PCR = reverse transcription–polymerase chain reaction.
* Chi-squared tests of association was performed to compare outcomes between women with symptomatic and asymptomatic infection for induction of delivery, cesarean delivery, pregnancy loss, preterm birth, infant ICU admission, and birth defects and was found to be statistically nonsignificant (p>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.

Abbreviations: ICU = intensive care unit; IQR = interquartile range; RT-PCR = reverse transcription–polymerase chain reaction.
*Including California [excluding Los Angeles County], Houston, Los Angeles County, Michigan, Minnesota, Nebraska, New Jersey, North Dakota, Oklahoma, Pennsylvania [excluding Philadelphia], Puerto Rico, Tennessee, and Vermont.
^† A total of 313 (10.9%) live births were reported as not tested during birth hospitalization, the remainder had no testing results reported.
^§ First positive test result occurred on the second day of life for 11 infants, on the third day for four, and on the fourth day for one.
^¶ Defined as either date of specimen collection for first positive test or symptom onset if exact date of collection was missing.
**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.