More than half of pregnant women admitted to the hospital with COVID-19 were asymptomatic, researchers found.
Of 598 hospitalized pregnant women with COVID-19, about 55% were asymptomatic, while 16% of symptomatic pregnant women were admitted to the intensive care unit (ICU), about 9% required mechanical ventilation, and two women died, reported Miranda Delahoy, PhD, of the CDC, and colleagues, writing in an early edition of the Morbidity and Mortality Weekly Report (MMWR).
Of 458 women who completed pregnancies at hospital discharge, 448 were live births, with 10 pregnancy losses, which occurred among both asymptomatic and symptomatic women. However, there were no ICU admissions, mechanical ventilation, or deaths among asymptomatic women, the authors noted.
“Testing policies based on the presence of symptoms might miss COVID-19 infections during pregnancy,” the researchers wrote. “Surveillance of pregnant women with COVID-19, including those with asymptomatic infections, is important to understand the short- and long-term consequences of COVID-19 for mothers and newborns.”
Current CDC testing policy states that if patients have been in close contact with someone with COVID-19 but do not have symptoms, patients “do not necessarily need a test” unless they are a “vulnerable individual” or at the discretion of their healthcare provider or state/local public health officials.
“Pregnant women account for a substantial proportion of COVID-19–associated hospitalizations among women of reproductive age,” Delahoy and co-authors added.
They examined data from COVID-NET, a population-based surveillance system for laboratory-confirmed COVID-19 infections, in 14 states, 13 of which contributed data to this report.
Among the 7,895 women ages 15-49 who were hospitalized with COVID-19, 598 were pregnant. They were a median age of 29, and among the 577 who reported race/ethnicity, about 43% were Hispanic and about 27% were non-Hispanic Black. About 21% of hospitalized pregnant women with COVID-19 had at least one underlying condition, including 8% with asthma and 4% with hypertension. Most women were hospitalized during the third trimester.
Reason of hospital admission was available for 324 women, and three-quarters were hospitalized for obstetric indications, including labor and delivery. About 20% were hospitalized for COVID-19-related illness, which was the most common reason for admission in the first and second trimester, while obstetric indications was the most common reason in the third trimester.
Among the 445 live births, 87.4% were term births and 13% were preterm. The researchers noted that this is higher than the 10% rate of preterm births in the general population in 2018. Of pregnancies resulting in live births, preterm delivery was reported for 23% of symptomatic pregnant women and 8% of asymptomatic pregnant women.
Two infants died, both born to symptomatic mothers requiring invasive mechanical ventilation.
Higher Rates of Preterm Delivery, Stillbirth
A second report in the MMWR, by Lakshmi Panagiotakopoulos, MD, of the CDC, and colleagues, not only found even higher rates of asymptomatic infection, but also higher preterm delivery prevalence and stillbirths among pregnant women hospitalized with COVID-19 versus baseline rates.
Examining data from the Vaccine Safety Datalink (VSD) surveillance system in eight U.S. healthcare centers from March 1 to May 30, the researchers found 105 hospitalized pregnant women with SARS-CoV-2 infection. The median age of all women was 30, and 62% were Hispanic or Latino.
Of the 62 women admitted for obstetric reasons, 50 (81%) were asymptomatic, similar to the proportion seen in New York City at the beginning of the pandemic.
Among 93 women who delivered, 15% were preterm deliveries, and 3% were stillbirths. The investigators noted that the preterm delivery prevalence was “nearly 70% higher than baseline rates in VSD during the study period” (9% among live births and stillbirths), and stillbirth prevalence “was nearly four times higher among women with SARS-CoV-2” than the VSD baseline rate during the study period (0.6%).
Of 43 women hospitalized for COVID-19 specifically, 30% required admission to the ICU, and 14% required mechanical ventilation. One woman died from COVID-19.
Not surprisingly, a larger proportion of pregnant women hospitalized with COVID-19 had pre-pregnancy obesity versus asymptomatic pregnant women hospitalized for obstetric reasons (44% vs 30%, respectively). Similar results were seen for prevalence of gestational diabetes in those hospitalized for COVID-19 versus those hospitalized for obstetric reasons (26% vs 8%).
Delahoy disclosed no conflicts of interest; co-authors reported relationships with MedImmune, Regeneron, PaxVax, Pfizer, GSK, Merck, Novavax, Sanofi-Pasteur, Micron, Janssen, AbbVie, Kentucky BioProcessing, and VBI Vaccines.
Panagiotakopoulos disclosed no conflicts of interest; co-authors disclosed support from Amgen, Merck & Co, Radius Health, O.N. Diagnostics, Pfizer, Sanofi Pasteur, GlaxoSmithKline, and Protein Science.