Association between COVID-19 by variant period and delivery-related outcomes in the United States

COVID-19 has been associated with adverse obstetric outcomes, but the magnitude of maternal and fetal risk may have varied across viral variant periods.

To assess the association between COVID-19 infection and delivery-related in-hospital and 90-day mortality, severe maternal morbidity (SMM), fetal outcomes (fetal death and preterm birth), and a set of utilization measures (including cesarean delivery, ICU admission, costs, and hospital length of stay [LOS]) in the United States.

A retrospective cohort study was conducted using delivery-related hospitalizations discharged between April 1, 2020, and March 31, 2023, from the Premier Healthcare Database. Regression modeling was conducted to evaluate variant-period-specific associations between COVID-19 exposure and key outcomes while controlling for a broad set of maternal risk factors.

Of the 2,561,615 evaluated delivery-related discharges, 53,226 (2.08%) were diagnosed with COVID-19. COVID-19 was associated with higher adjusted odds of in-hospital mortality across the Pre-Alpha, Alpha, Delta, and first Omicron phases (aOR [p-adj]: 13.11 [<.001], 13.03 [<.001], 29.47 [<.001], and 3.55 [.04]), respectively. Maternal COVID-19 infection was further associated with increased odds of fetal death at 20 or more weeks of gestation across the Pre-Alpha (aOR: 1.53 [1.28-1.83, < .001]) and Delta (3.37 [2.95-3.84, < .001]) phases. The odds of experiencing any SMM, ICU admission, or preterm birth were significantly higher across all phases of the pandemic, whereas the odds of cesarean delivery were significantly higher during all but the Alpha and first Omicron phases. COVID-19 infection was associated with increased LOS and hospital costs throughout all variant phases.

COVID-19 infection during delivery was associated with higher odds of maternal, fetal, and utilization outcomes at varying stages of the pandemic, with the most notable effect during the Delta period. These findings provide insight into the variant-dependent obstetric burden of COVID-19 and for maternal health surveillance and clinical preparedness during future infectious disease outbreaks.