Research Summary

COVID-19 Vaccination During Pregnancy Linked to Reduced Preeclampsia Risk in Multinational INTERCOVID Cohort

Edited by:
Kate Young

Key Highlights

  • COVID-19 infection during pregnancy was associated with a 45% increased odds of preeclampsia, rising to 78% among unvaccinated women.
  • COVID-19 vaccination with a booster dose reduced the odds of preeclampsia by approximately 33% overall.
  • Among women with pre-existing morbidities, booster vaccination reduced the odds of preeclampsia by up to 58%.
  • Booster vaccination was also associated with lower maternal and perinatal morbidity, mortality, and preterm birth.

COVID-19 vaccination during pregnancy may reduce the odds of preeclampsia, according to findings from a large multinational cohort study published in eClinicalMedicine. Investigators from the INTERCOVID consortium analyzed data across the pandemic to assess whether vaccination modifies the established association between SARS-CoV-2 infection and hypertensive disorders of pregnancy.

The study confirmed that COVID-19 infection is independently associated with increased odds of preeclampsia and found that vaccination, particularly with a booster dose, was associated with reduced odds of developing the condition during pregnancy.

Researchers conducted a prospective analysis of 6527 pregnant women enrolled across 40 hospitals in 18 countries between March 2020 and June 2022. Participants included women diagnosed with COVID-19 and contemporaneous controls without infection, recruited using standardized protocols.

Vaccination status was categorized as unvaccinated, vaccinated (partial or complete), or boosted. Multivariable logistic regression models adjusted for maternal demographics, comorbidities, and clinical factors were used to estimate the association between vaccination and preeclampsia. Stratified and survival analyses further evaluated outcomes by infection status and pre-existing conditions.

Study Findings

In the cohort, 33.2% of women were diagnosed with COVID-19, and 5.1% developed preeclampsia. SARS-CoV-2 infection was associated with increased odds of preeclampsia (adjusted odds ratio [aOR], 1.45; 95% CI, 1.15–1.84), with a stronger association among unvaccinated women (aOR, 1.78; 95% CI, 1.31–2.42).

Vaccination demonstrated a protective effect. While any vaccination showed a non-significant reduction in odds (aOR, 0.85; 95% CI, 0.65–1.10), receipt of a booster dose significantly reduced preeclampsia odds (aOR, 0.67; 95% CI, 0.45–0.99). Among women with pre-existing morbidities, booster vaccination was associated with a 58% reduction in odds (aOR, 0.42; 95% CI, 0.20–0.87).

Additional findings showed that booster vaccination was associated with reduced maternal morbidity and mortality (aOR, 0.68), perinatal morbidity and mortality (aOR, 0.71), and preterm birth (aOR, 0.67).

Clinical Implications

According to the study authors, the findings suggest that COVID-19 vaccination—particularly with a booster dose—may reduce the odds of preeclampsia and improve maternal and perinatal outcomes, reinforcing recommendations to vaccinate pregnant women, especially those with pre-existing conditions.

The authors noted that the observational design introduces potential selection bias and residual confounding. They also highlighted limited statistical power for subgroup analyses and possible misclassification of COVID-19 status during early phases of the pandemic.

Expert Commentary

“This analysis confirms the association between SARS-CoV-2 infection and [preeclampsia] with an increase of 45% risk during the pandemic and 78% among unvaccinated women during the same period, adjusted for major risk factors,” the study authors concluded. “Importantly, for a disease of uncertain aetiology such as [preeclampsia], we have demonstrated that vaccination with a booster dose, after adjusting for a comprehensive set of possible confounding variables including COVID-19 diagnosis, study site and year of the pandemic, reduced the odds of PE by over 30% in the complete cohort and by about 58% among women with pre-existing morbidities. This protective effect was consistently extended to other severe maternal and perinatal morbidity and mortality indicators.”

Reference
Cavoretto PI, Villar J, Farina A, et al. COVID-19 vaccination status during pregnancy and preeclampsia risk: the pandemic-era cohort of the INTERCOVID consortium. eClinicalMedicine. 2026;103785. doi:10.1016/j.eclinm.2026.103785