WEDNESDAY, Feb. 25, 2026 (HealthDay News) -- COVID-19 vaccination, especially with a booster dose, is associated with reduced odds of preeclampsia (PE), according to a study published online Feb. 18 in eClinicalMedicine.
Paolo Ivo Cavoretto, M.D., Ph.D., from IRCCS San Raffaele Hospital in Milan, and colleagues analyzed individual-level data from pregnant women prospectively enrolled from 18 countries in two consecutive cohorts between 2020 and 2022 during the COVID-19 pandemic to examine whether vaccination affects the risks for PE.
Of 6,527 pregnant women, 2,166 (33.2 percent) and 3,753 (57.5 percent) were diagnosed with COVID-19 and were unvaccinated, respectively. Overall, 64.7 percent of the 2,774 vaccinated women received mRNA vaccines; 848 (30.6 percent) received a booster dose in addition to the initial regimen. The researchers observed an independent association between COVID-19 and PE (adjusted odds ratio, 1.45), especially in unvaccinated women (adjusted odds ratio, 1.78). Vaccination had a protective effect against PE during the index pregnancy, after adjustment for confounders (adjusted odds ratio, 0.85), which was stronger with a booster dose (adjusted odds ratio, 0.67). The odds were reduced among women with preexisting morbidities who received a booster dose (adjusted odds ratio, 0.42), which was mainly seen in women diagnosed with COVID-19. The magnitude of the effect was not altered with adjustment for study site and cohort year.
"We now have evidence that maternal vaccination may influence pathways involved in preeclampsia development, suggesting a broader immunological or vascular benefit of vaccination," senior coauthor José Villar, M.D., M.P.H., Ph.D., from the University of Oxford in the United Kingdom, said in a statement.