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Infant Outcomes Following Maternal Infection with SARS-CoV-2: First Report from the PRIORITY Study

Our take —

This prospective cohort study provides reassuring preliminary data on adverse birth outcomes among infants whose mothers are infected with SARS-CoV-2 during pregnancy. There were no major differences in preterm birth, neonatal intensive care admission, or infant respiratory distress by maternal SARS-CoV-2 history during pregnancy. However, the control group included mothers with suspected SARS-CoV-2 infection who tested negative, many of whom had symptoms. Also, this study did not adjust for any covariates that might confound the observed relationships. More studies are required before reaching conclusions about the risks of adverse infant events after maternal SARS-CoV-2 infection.

Study design

Prospective Cohort

Study population and setting

This prospective study included birth outcomes from 263 infants whose mothers had suspected or confirmed SARS-CoV-2 infection during, or 6 weeks after, pregnancy (the PRIORITY prospective cohort study, including patients from 100 US hospitals). Enrollment began on March 22, 2020, data were collected on additional infant outcomes beginning May 13, and outcomes were assessed through June 22. Most outcomes came from maternal report and a convenience sample of reported outcomes were validated against electronic medical record data from birth hospitals. This study included 179 (68%) infants whose mothers tested positive for SARS-CoV-2 and 84 (32%) infants (32%) whose mother tested negative. Outcome frequencies were compared by maternal SARS-CoV-2 infection status using Fisher’s exact tests and chi-squared tests.

Summary of Main Findings

This study found no statistically significant differences by maternal SARS-CoV-2 infection status in gestational age at birth, preterm birth, vaginal delivery, birth defects, breast milk after birth, neonatal intensive care unit admission, abnormal newborn examination, infant positive for SARS-CoV-2, difficulty breathing, upper respiratory infections, apnea, rooming with the mother, or breast feeding at 6-8 weeks. Two babies tested positive for SARS-CoV-2, both of whom had minimal symptoms and mothers who tested positive for SARS-CoV-2. Infants whose mothers tested positive for SARS-CoV-2 14 or fewer days before delivery were more likely to be born early and require neonatal intensive care unit admission than those whose mothers were infected earlier during pregnancy. Among included mothers, 146 (81.6%) of the 179 who tested positive for SARS-CoV-2 reported symptoms (not described). Among mothers who tested negative, 53 (63.1%) also reported symptoms (also not described). Mothers in both groups had a mean age of approximately 32 years, and reported similar proportions of races/ethnicities, college graduates, and income levels ≥ $100,000. Geographic distributions differed between groups. Finally, mothers who tested positive for SARS-CoV-2 were more likely to report being in the intensive care unit at the time of study enrollment (6 vs. 0 women).

Study Strengths

In a validation subsample (34% of mothers with SARS-CoV-2 infection and 55% of those without), all reported outcomes matched outcomes from medical records. Birth outcomes were prospectively assessed at various stages of pregnancy.


All included mothers had suspected or confirmed SARS-CoV-2 infection; thus, mothers testing negative are not representative of the broader population of mothers without infection. Indeed, false negatives within this group are a concern, given reliance on RT-PCR for diagnosis. This study included 16 women who tested positive for SARS-CoV-2 up to 6 weeks from delivery, which means that some infants were not exposed to SARS-CoV-2 in utero, and thus birth outcomes of interest possibly occurred before exposure. The authors assessed associations for many outcomes, but did not adjust the level of statistical significance for multiple tests or comment on the likelihood of false positive tests. The authors neither measured nor adjusted for variables that may confound the relationship between SARS-CoV-2 exposure in utero and adverse infant birth outcomes such as maternal hypertension, diabetes, or smoking status. They also did not control for measured confounders such as age or geographic region. Finally, this is a small, preliminary analysis of the ongoing PRIORITY study, and it is unclear if these data are representative of future data.

Value added

This is one of the first studies to characterize birth outcomes by maternal SARS-CoV-2 status during pregnancy, and includes women from across the United States.

This review was posted on: 9 October 2020