Pre-Delta, Delta, and Omicron Periods of the Coronavirus Disease 2019 (COVID-19) Pandemic and Health Outcomes During Delivery Hospitalization.

Objective: To examine the relationship between coronavirus disease 2019 (COVID-19) diagnosis at delivery and adverse maternal health and pregnancy outcomes during pre-Delta, Delta, and Omicron variant predominance, with a focus on the time period of Omicron variant predominance.

Methods: We conducted a cross-sectional observational study with data from delivery hospitalizations in the Premier Healthcare Database from February 2020 to August 2023. The pre-Delta (February 2020-June 2021), Delta (July 2021-December 2021), and Omicron (January 2022-August 2023) periods of variant predominance were examined. Exposure to COVID-19 was identified by having a diagnostic code for COVID-19 during the delivery hospitalization. Adjusted prevalence ratios (aPRs) were calculated to compare the risks of adverse maternal and pregnancy outcomes for women with and without COVID-19 diagnoses at the time of delivery for each variant period.

Results: Among 2,990,973 women with delivery hospitalizations, 1.9% (n=56,618) had COVID-19 diagnoses noted at delivery admission discharge, including 26,053 during the Omicron period. Across all variant time periods, the prevalence of many adverse maternal and pregnancy outcomes during the delivery hospitalization was significantly higher for pregnant women with COVID-19 compared with pregnant women without COVID-19. In adjusted models, COVID-19 during the Omicron period was associated with significant increased risks for maternal sepsis (COVID-19: 0.4% vs no COVID-19: 0.1%; aPR 3.32, 95% CI, 2.70-4.08), acute respiratory distress syndrome (0.6% vs 0.1%; aPR 6.19, 95% CI, 5.26-7.29), shock (0.2% vs 0.1%; aPR 2.14, 95% CI, 1.62-2.84), renal failure (0.5% vs 0.2%; aPR 2.08, 95% CI, 1.73-2.49), intensive care unit admission (2.7% vs 1.7%; aPR 1.64, 95% CI, 1.52-1.77), mechanical ventilation (0.3% vs 0.1%; aPR 3.15, 95% CI, 2.52-3.93), in-hospital death (0.03% vs 0.01%; aPR 5.00, 95% CI, 2.30-10.90), stillbirth (0.7% vs 0.6%; aPR 1.17, 95% CI, 1.01-1.36), and preterm delivery (12.3% vs 9.6%; aPR 1.28, 95% CI, 1.24-1.33).

Conclusion: Despite the possibility of some level of immunity due to previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, vaccination, or testing differences, risks of adverse outcomes associated with COVID-19 diagnosis at delivery remained elevated during the Omicron variant time period.