(798) A multi-state analysis of preterm birth trends by COVID-19 vaccination status in the United States

We performed a population-based cohort study using the Vizient® clinical database, which included data from 192 hospitals in 38 states. We included pregnant persons who delivered between January 2021-April 2022. Pregnant persons were grouped into three categories: unvaccinated; incompletely vaccinated (one dose of Pfizer or Moderna); or completely vaccinated (one dose of Johnson & Johnson or ≥ two doses of Moderna or Pfizer). We examined the association between vaccination status and PTB at < 28, < 34, and < 37 weeks of gestation. Demographics and outcomes were analyzed using standard statistical tests. Multivariable logistic regression models were used to adjust for potential confounders, with adjusted odds ratio (aOR) as the measure of treatment effect.

Results:

Of 403,766 persons who met our inclusion criteria, 41,212 (10.2%) experienced PTB between 20 and 37 weeks. Persons experiencing PTB were older, less likely to be vaccinated against COVID-19, more likely to undergo cesarean delivery, and more likely to have co-morbid conditions (Table 1). Completely vaccinated persons had a 39% reduction in the risk of PTB at < 28 weeks (aOR 0.61, 95% CI 0.40-0.93, p=0.02), a 33% reduction in the risk of PTB at < 34 weeks (aOR 0.67, 95% CI 0.54-0.84, p < 0.001) and a 20% reduction in PTB at < 37 weeks of gestation (aOR 0.80, 95% CI 0.71-0.90, p < 0.001) when compared to unvaccinated persons (Figure 1). In adjusted analyses, PTB was not significantly different between unvaccinated and incompletely vaccinated persons.

Conclusion:

Compared to unvaccinated pregnant persons, complete vaccination against COVID-19 may be associated with lower rates of PTB.