Study examines prevalence of COVID-19 infections in pregnant women

Universal testing of pregnant women admitted to labor and delivery units is part of a multipronged approach to reducing transmission of the virus that causes the novel coronavirus (COVID-19) in hospitals and clinics. A team led by investigators at Massachusetts General Hospital has now provided a report on the prevalence of infections with the virus in women admitted to such units in several Boston hospitals. The findings are published in Infection Control & Hospital Epidemiology.

Universal testing in the labor and delivery units began more than 30 days after physical distancing orders were placed in Massachusetts. Over 18 days of universal testing in units at the four major hospitals affiliated with Mass General Brigham Health, which provides maternity care to approximately 14,750 women per year, 757 women were tested. Of those tested, 139 had symptoms possibly consistent with COVID-19.

Among symptomatic women, 7.9 percent tested positive for SARS-CoV-2, the virus that causes COVID-19. Among asymptomatic women, 1.5 percent tested positive. Thus, nine of the 20 women, or 45 percent, who tested positive at admission had no symptoms of COVID-19. Across the four hospitals, none of the positive asymptomatic women developed COVID-19 symptoms during their hospitalization, and all 9 newborns tested negative for the SARS-CoV-2, according to the study.

"Although our results indicate a low prevalence of SARS Cov-2 in an asymptomatic pregnant population,” said said Ilona Telefus Goldfarb, MD, MPH, lead author of the study and maternal-fetal medicine specialist at Mass General and Harvard Medical School in a statement, “my coauthors and I believe that universal testing of this population can provide a window into the community prevalence of infection, which can in turn help guide decision-making about moving between mitigation versus containment measures in the hospital and in the community.”

The researchers noted that universal testing in this specific patient population is an especially important public health priority given the potential dangers of COVID-19 for maternal and newborn care during and after birth.

"Our findings underscore the importance of understanding the local prevalence of disease, which varies across geographical areas and will change over time due to many factors,” said Erica Shenoy, MD, PhD, co-senior author and associate chief of Mass General's Infection Control Unit, in a statement. “Tracking prevalence prospectively can inform public health interventions and our approaches to testing.”

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