A multinational study led by researchers at the University of Oxford has found a significant reduction in the risk of preeclampsia, a serious pregnancy complication, among women vaccinated against COVID-19, particularly those who received a booster dose. The findings, published in eClinicalMedicine, analyzed data from 6,527 pregnant women across 18 countries enrolled between 2020 and 2022.
Researchers compared vaccination status among pregnant women, both with and without SARS-CoV-2 infection, to determine the influence of vaccination on preeclampsia rates. The study revealed that COVID-19 infection during pregnancy was associated with a 45% increased risk of preeclampsia, escalating to a 78% increase among unvaccinated women.
Vaccination demonstrated an overall reduction in the odds of preeclampsia, with a 33% decrease observed among women who received a booster dose, a result deemed statistically significant. The protective effect was particularly pronounced for women with pre-existing health conditions, including diabetes, hypertension, and thyroid disorders, where vaccination with a booster cut preeclampsia risk by 42%, also statistically significant.
The study’s findings suggest the protective benefits of COVID-19 vaccination extend beyond mitigating the severity of infection, offering a potential preventative measure against preeclampsia regardless of infection status. Vaccinated women in the study also experienced lower rates of preterm delivery, maternal and perinatal morbidity, and mortality, according to the research.
The INTERCOVID Consortium’s research builds on earlier findings indicating a protective effect of COVID-19 vaccination against preeclampsia. A February 18th publication in eClinicalMedicine similarly pointed to vaccination as protective, with the effect strengthening with booster doses. The University of Oxford announced the latest findings on February 20, 2026, highlighting the unprecedented insight the study provides into preeclampsia prevention.
