Ferrara A, Hedderson MM, Zhu Y, et al. Perinatal complications in individuals in California with or without SARS-CoV-2 infection during pregnancy. JAMA Intern Med. 2022;182:503-512. doi:10.1001/jamainternmed.2022.0330
Expert Commentary
SARS-CoV-2 infection is associated with several adverse outcomes, with the magnitude of specific risks varying by population studied and study design used. Early Centers for Disease Control and Prevention (CDC) data demonstrated that pregnant women were at increased risk for severe illness, including risks of intensive care unit (ICU) admission, invasive ventilation, and extracorporeal membrane oxygenation, compared with non–pregnant women.1 Since then, other groups have confirmed the increased risks of severe COVID-19, and also identified pregnancy-specific risks, such as preeclampsia, cesarean delivery (CD), prematurity, venous thromboembolic (VTE) disease, and stillbirth.2-6
The recent study by Ferrara and colleagues adds more granular data to help refine understanding of COVID-19 in pregnancy and counsel patients.
Details of the study
The authors conducted a retrospective cohort study between March 1, 2020, and March 16, 2021, using the electronic health records (EHRs) from Kaiser Permanente Northern California, an integrated managed care organization that serves 4.5 million patients annually. Universal testing for SARS-CoV-2 upon admission for delivery began December 1, 2020; prior to this date, asymptomatic pregnant women were tested only for certain criteria (such as being a health care worker or having high-risk medical conditions).
Pregnant women were identified with SARS-CoV-2 based on 1) a positive polymerase chain reaction test result between 30 days prior to the last menstrual period up to 7 days after delivery or 2) an ICD-10 diagnosis of SARS-CoV-2 infection. Pregnant women not meeting these criteria were classified as SARS-CoV-2 negative. Women were followed through pregnancy to understand if they experienced preterm birth (spontaneous and medically indicated), gestational hypertension, preeclampsia/eclampsia, VTE disease, gestational diabetes, severe maternal morbidity (as defined by the CDC), hospitalization, and livebirth (or stillbirth), in order to consider the timing of SARS-CoV-2 infection relative to each of these outcomes (and ascertain whether SARS-CoV-2 infection preceded any of these outcomes more commonly than not). Management of pregnancies with COVID-19 across this large organization and multiple hospitals was not specified.
Identified perinatal risks
Among 43,886 pregnant women included in the cohort, 1,332 (3.0%) were diagnosed with SARS-CoV-2, with the vast majority of positive tests in the third trimester. Significant sociodemographic differences were noted between those with and without SARS-CoV-2, including differences in age, self-reported race/ethnicity, neighborhood deprivation index, and pre-pregnancy body mass index; no differences were noted for other pre-existing comorbidities, gestational week at delivery, or smoking in pregnancy.
In multivariable models, SARS-CoV-2 infection in pregnancy was associated with severe maternal morbidity, preterm birth, and VTE disease. It was not associated with stillbirth, any hypertensive disorder of pregnancy, CD, or any neonatal complication.
The prevalence of SARS-CoV-2 was 1.3% prior to and 8.0% after implementation of universal testing in pregnancy for SARS-CoV-2. No differences were noted in the risks of severe maternal morbidity or preterm birth relative to the implementation of universal testing, with risks remaining comparably high even after universal testing.
A total of 307 of the 1,332 pregant women with SARS-CoV-2 were admitted to the hospital for symptomatic infection; 3 required noninvasive positive-pressure ventilation, and 1 required mechanical ventilation.
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