COVID-19 Vaccine During Pregnancy Cuts Preeclampsia Risk: Study

Catching COVID-19 during pregnancy significantly raises the risk of preeclampsia – a dangerous blood pressure disorder – but new research finds that vaccination offers substantial protection against this serious complication. The findings, published in February 2026 in eClinicalMedicine, add to a growing body of evidence supporting COVID-19 vaccination for pregnant individuals.

Researchers analyzed data from over 6,500 pregnant women across 18 countries between 2020 and 2022. They found that COVID-19 infection increased the risk of preeclampsia by 45% compared to those who remained uninfected. However, for unvaccinated women who contracted the virus, the risk jumped by a concerning 78%. This underscores the heightened vulnerability of unvaccinated pregnant people to severe outcomes from COVID-19.

A Protective Effect, Especially with Boosters

The study revealed that vaccination significantly lowered this risk. Completing an initial COVID-19 vaccine series and receiving an updated booster dose was associated with a 33% overall reduction in preeclampsia risk. The benefit was even more pronounced for individuals with pre-existing medical conditions like diabetes, where a booster dose led to a 58% decrease in risk. This suggests that vaccination not only provides a baseline level of protection but also strengthens immunity for those who are more vulnerable.

Preeclampsia affects approximately 3% to 8% of pregnancies, typically developing in the latter half of pregnancy or shortly after childbirth. The World Health Organization describes it as a condition marked by persistent high blood pressure and often, protein in the urine, indicating potential kidney damage. Other symptoms can include vision problems, severe headaches, and sudden swelling. It’s a serious condition that can lead to complications for both mother and baby, including liver and kidney damage, heart strain, and placental disruption, and in severe cases, can progress to eclampsia – a life-threatening condition involving seizures.

While the exact cause of preeclampsia remains unknown, research suggests it may be linked to abnormal placental development. Some studies propose that placental dysfunction either drives the condition or is a consequence of it. Increasingly, evidence points to a role for viral infections, like COVID-19, in triggering changes in the immune system and causing blood vessel dysfunction – a key process in the development of preeclampsia symptoms. Recent research supports this connection.

Dr. José Villar, a professor of perinatal medicine at the University of Oxford and co-lead author of the study, told Live Science that these findings could be a “breakthrough” in understanding the potential links between viruses and preeclampsia. The team theorized that COVID-19 vaccines might protect against preeclampsia by reducing the likelihood of infection and severe illness, and by generally boosting the immune system.

The study’s findings align with separate research published in 2024, which demonstrated that women who received at least one dose of a COVID-19 vaccine were less likely to experience preterm birth or stillbirth. Dr. Elena Raffetti, an assistant professor at the Karolinska Institute in Sweden and first author of that report, emphasized that vaccinations are safe and protective against several risks, and did not increase the risk of preeclampsia.

The American College of Obstetricians and Gynecologists currently recommends that pregnant individuals receive an updated COVID-19 vaccine as soon as possible – whether planning a pregnancy, during any trimester, or while breastfeeding or postpartum.

Study Limitations and Future Research

It’s important to note that this study, like all research, has limitations. While researchers accounted for factors like age, smoking history, and pre-existing conditions, there may be other differences between vaccinated and unvaccinated groups that influenced the results. The study authors acknowledge this and call for further research to investigate the complex interplay between the immune system, viral infections, and preeclampsia.

Specifically, future studies should focus on understanding how viral infections may contribute to preeclampsia by triggering changes in the immune system and causing blood vessel dysfunction. Unraveling these mechanisms could lead to new prevention strategies and improved care for pregnant individuals at risk.

The findings reinforce the importance of staying up-to-date with recommended vaccinations during pregnancy. As public health recommendations evolve based on emerging evidence, it’s crucial to consult with a healthcare provider for personalized guidance. Ongoing surveillance and research will continue to refine our understanding of COVID-19’s impact on pregnancy and the protective benefits of vaccination.