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SARS-CoV-2 Infection Among Hospitalized Pregnant Women: Reasons for Admission and Pregnancy Characteristics — Eight U.S. Health Care Centers, March 1–May 30, 2020

Our take —

This descriptive study of 105 pregnant women hospitalized with COVID-19 at eight U.S. surveillance sites demonstrated a significantly higher risk profile among pregnant cases admitted for non-obstetric reasons compared to those hospitalized for obstetric reasons, underscoring the need to consider the relative proportion of these sub-populations when interpreting and comparing hospital-based studies of COVID-19 in pregnancy. Though preterm birth and stillbirth were more prevalent among this small sample of pregnant women with COVID-19 than among all births at the facilities, this study does not establish whether this crude difference may be attributable to COVID-19 or to higher levels of other established risk factors among those with COVID-19 (e.g. 10% of the sample had a history of preterm birth).

Study design

Case Series

Study population and setting

This study used data from the US Vaccine Safety Datalink surveillance system to describe the characteristics and outcomes of pregnant women hospitalized with COVID-19 in 8 health care systems. Among the 4,408 people hospitalized with COVID-19 at surveillance sites from March 1 to May 30, 2020, 105 were pregnant (median age 30 years; 62% Hispanic/Latina; median gestational age 38 weeks). Data were abstracted from medical records and the reasons for hospital admission were adjudicated by a physician.

Summary of Main Findings

During the study period, 41% (43) of the pregnant women were hospitalized for COVID-19 without an obstetric indication, while the remaining 59% (62) were admitted for labor or other obstetric reasons. Among the latter, 80% (50) were asymptomatic. Compared to the women hospitalized for obstetric reasons, women hospitalized for COVID-19 were earlier in pregnancy, had a higher prevalence of pre-pregnancy obesity and gestational diabetes, and accounted for all but one Intensive Care Unit admission. Overall, 14 (15%) of the 93 women with completed pregnancies delivered preterm (labor was induced because of respiratory distress in 3 of these cases), and there were 3 (3%) stillbirths, one with placental abruption and two without known etiology. The prevalence of preterm birth and stillbirth were similar regardless of indication for hospitalization or the presence of symptoms but were higher than the overall prevalence at the same facilities among all pregnant women in the Vaccine Safety Datalink surveillance system during the same period of 8.9% preterm birth and 0.6% stillbirth.

Study Strengths

The reason for hospital admission was adjudicated by a clinician, enabling the authors to appropriately stratify outcomes and characteristics of pregnant women with COVID-19. There was much less data missing for this sample in comparison to previous studies of COVID-19 in pregnancy using other surveillance systems. This allowed the authors to characterize important risk factors for COVID-19 severity and adverse birth outcomes for all 105 pregnant women hospitalized with COVID-19 at the surveillance sites during the study period.

Limitations

The study did not include a comparison group of pregnant women without COVID-19 to evaluate whether COVID-19 was associated with adverse birth outcomes. The surveillance system captured a relatively small number of pregnant women, and it is unclear how the population at the surveillance sites compares to the population of pregnant women in the US.

Value added

This study documented that pregnant women with COVID-19 who are hospitalized for non-obstetric reasons differ significantly from cases who are hospitalized for obstetric reasons, with the former group including more women in earlier stages of pregnancy, having a higher prevalence of underlying and gestational comorbidities, and a higher prevalence of COVID-19 disease severity. COVID-19 screening policies in antenatal and maternity care have varied between health systems and over time, and many existing studies of COVID-19 in pregnancy have been unable to differentiate between these subpopulations.

This review was posted on: 9 October 2020