Intensive care unit admissions for pregnant and nonpregnant women with coronavirus disease 2019

To the Editors:

We enjoyed reading the article by Blitz et al¹ entitled “Intensive care unit admissions of pregnant and nonpregnant women with coronavirus disease 2019,” recently published in the American Journal of Obstetrics & Gynecology. The researchers did not find an increased risk for intensive care unit (ICU) admission in hospitalized pregnant women diagnosed with coronavirus disease 2019 (COVID-19) compared with those who were not pregnant and concluded that the results were reassuring as they indicated that pregnant women infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may not experience more severe disease progression than nonpregnant women.

This is in variance with a recent report from the Public Health Agency of Sweden.² This report was based on a comprehensive analysis of all pregnant or postpartum women and nonpregnant women with laboratory-confirmed SARS-CoV-2 infection who had been treated in ICUs in Sweden between March 19, 2020 and April 20, 2020. Cases were identified in a special reporting module within the Swedish Intensive Care Registry (SIR). Overall, 53 women aged 20 to 45 years with SARS-CoV-2 infection were reported in the SIR, and 13 of them either were pregnant or had recently given birth. The results indicated that the risk of being admitted to the ICU was higher in pregnant and postpartum women with COVID-19 in Sweden than in nonpregnant women of similar age. The incidence of requiring intensive care in Sweden in conjunction with laboratory-confirmed SARS-CoV-2 infection during the study period was 14.4 per 100,000 (95% confidence interval [CI], 7.3–23.4) for pregnant or postpartum women compared with 2.5 per 100,000 (95% CI, 1.8–3.5) for nonpregnant women in the same age group (relative risk [RR], 5.39; 95% CI, 2.89–10.08). The incidence of requiring invasive mechanical ventilation in the ICU among pregnant or postpartum women and nonpregnant women with laboratory-confirmed SARS-CoV-2 was 7.4 per 100,000 and 1.8 per 100,000, respectively (RR, 3.48; 95% CI, 1.86–6.52).

Obviously, these 2 studies were carried out in different settings, and there could be differences with regard to population characteristics, prevalence of risk factors, or even thresholds for ICU admissions, which may partly explain the differences in findings. However, most importantly, in the New York study, the denominator consisted of hospital cohorts, whereas in the Swedish study, the denominator consisted of all pregnant and nonpregnant women aged 20 to 45 years. These 2 studies illustrate an inherent problem associated with lack of a common denominator in many reported studies on COVID-19, which has resulted in conflicting and sometimes misleading conclusions.

Increasingly, more serious outcomes, including maternal mortalities, have been reported among pregnant women from both low- and high-resource settings.³ Therefore, we believe that the reporting should be transparent, and the risk of COVID-19 in pregnancy should not be downplayed.⁴