Berlin – New research published this week offers compelling evidence that COVID-19 vaccination during pregnancy, particularly with booster doses, significantly reduces the risk of preeclampsia, a serious and potentially life-threatening complication of pregnancy. The findings, stemming from a large multinational study, provide unprecedented insight into preeclampsia prevention, independent of whether a woman contracts the SARS-CoV-2 virus. This is particularly encouraging news for expectant mothers and healthcare providers as they navigate ongoing public health considerations.
Preeclampsia, characterized by high blood pressure and signs of damage to another organ system, typically affects between 3% and 8% of pregnancies globally. While the exact cause remains elusive, it’s understood to involve inflammation and dysfunction of blood vessels – pathways similarly impacted by COVID-19 infection. The study, published in eClinicalMedicine on February 18, 2026, analyzed data from over 6,500 pregnant women across 18 countries, offering a robust and geographically diverse dataset.
The research team, part of the INTERCOVID Consortium led by researchers at the University of Oxford, meticulously compared vaccinated and unvaccinated women, both with and without SARS-CoV-2 infection, to determine the influence of vaccination status on preeclampsia rates. The results demonstrate a clear protective effect, especially when vaccination is up-to-date with booster doses. This adds to the growing body of evidence supporting the safety and benefits of COVID-19 vaccination during pregnancy.
COVID-19 Infection and Preeclampsia Risk
The study unequivocally demonstrated a heightened risk of preeclampsia associated with COVID-19 infection during pregnancy. Researchers found that contracting COVID-19 increased the overall risk of developing preeclampsia by 45%. However, this risk was substantially higher – soaring to 78% – among pregnant women who remained unvaccinated. This underscores the vulnerability of unvaccinated expectant mothers to severe complications from the virus.
Vaccination Offers Significant Protection
Crucially, the study revealed that vaccination offered a significant degree of protection against preeclampsia. Women who received a booster dose experienced a 33% reduction in the odds of developing the condition, a statistically significant finding. This protective effect was even more pronounced among women with pre-existing health conditions, such as diabetes, hypertension, or thyroid disorders, where a booster dose cut preeclampsia risk by 42%, also statistically significant. These findings suggest that vaccination may be particularly beneficial for those with underlying health vulnerabilities.
Researchers emphasize that the protective effect of vaccination remained consistent even after adjusting for key factors, suggesting benefits independent of COVID-19 infection status. This is a critical observation, implying that vaccination may offer broader benefits for preeclampsia prevention, even in the absence of exposure to the virus. The study also noted that vaccinated women experienced lower rates of preterm delivery, maternal morbidity, and perinatal mortality, further highlighting the positive impact of vaccination on pregnancy outcomes.
Understanding the Mechanism: Beyond COVID-19 Infection
The INTERCOVID Consortium’s research suggests that the benefits of vaccination extend beyond simply mitigating the risks associated with COVID-19 infection. Dr. José Villar, principal investigator of the INTERCOVID Consortium and professor of perinatal medicine at the University of Oxford, explained that the findings indicate vaccination may influence the pathways involved in preeclampsia development. “Now we have evidence that maternal vaccination can influence the pathways involved in the development of preeclampsia, suggesting a broader immunological or vascular benefit of vaccination,” he stated. This suggests that the vaccine may “train” the immune system to better manage inflammation, contributing to healthier placental function and blood vessel health throughout pregnancy.
The Role of Inflammation and Vascular Health
Preeclampsia is characterized by widespread inflammation and impaired vascular function. COVID-19 infection is also known to trigger significant inflammation and can damage blood vessels. The researchers hypothesize that vaccination may help to modulate the immune response, reducing inflammation and protecting vascular health, thereby lowering the risk of preeclampsia. This is an area of ongoing investigation, but the current findings provide a strong rationale for further research into the immunological mechanisms underlying the protective effect of vaccination.
Study Details and Methodology
The study, published in eClinicalMedicine, involved a retrospective analysis of data from 6,527 pregnant women admitted to 40 hospitals across 18 countries between 2020 and 2022. Researchers carefully matched women with a documented COVID-19 diagnosis to control groups without the infection within the same hospital setting. Of the 2,774 vaccinated women included in the analysis, 1,795 (64%) received mRNA vaccines, and 848 (31%) also received a booster dose, with 67% of those boosters being mRNA-based. This detailed analysis allowed researchers to isolate the effects of vaccination while accounting for the confounding factor of COVID-19 infection.
Dr. Jagjit Teji, a neonatologist at the Ann &. Robert H. Lurie Children’s Hospital of Chicago and co-author of the study, emphasized the importance of strengthening COVID-19 vaccination programs during pregnancy, particularly focusing on booster doses and ensuring equitable access to vaccines worldwide. “Our results support the importance of strengthening COVID-19 vaccination programs during pregnancy, emphasizing boosters and ensuring equitable access to vaccines globally,” he said in a press statement released on February 11, 2026.
Implications for Public Health and Future Research
These findings have significant implications for public health recommendations regarding COVID-19 vaccination during pregnancy. The Centers for Disease Control and Prevention (CDC) currently recommends that pregnant people receive an updated 2024-2025 COVID-19 vaccine, regardless of prior vaccination status. The CDC provides detailed guidelines on COVID-19 vaccines during pregnancy and breastfeeding. This new research reinforces that recommendation and highlights the added benefit of booster doses.
Further research is needed to fully elucidate the mechanisms underlying the protective effect of vaccination against preeclampsia. Investigating the specific immunological pathways involved could lead to the development of novel strategies for preeclampsia prevention and treatment. Ongoing surveillance of pregnancy outcomes in vaccinated and unvaccinated populations will be crucial to monitor the long-term impact of vaccination on maternal and infant health.
Key Takeaways
- COVID-19 infection significantly increases the risk of preeclampsia during pregnancy.
- COVID-19 vaccination, especially with booster doses, substantially reduces this risk.
- Vaccination appears to offer protection even in the absence of COVID-19 infection, potentially by improving immune function and vascular health.
- The findings underscore the importance of COVID-19 vaccination during pregnancy for both maternal and infant health.
The INTERCOVID Consortium continues to analyze data and conduct research to further understand the complex interplay between COVID-19, vaccination, and pregnancy outcomes. The next phase of their research will focus on identifying specific biomarkers associated with preeclampsia risk and evaluating the effectiveness of different vaccine regimens. Expectant mothers are encouraged to discuss their vaccination status with their healthcare providers to make informed decisions about their health and the health of their babies.
This research provides a vital piece of the puzzle in understanding and mitigating the risks associated with pregnancy during the ongoing pandemic. Continued vigilance, vaccination, and ongoing research will be essential to protect the health of mothers and newborns worldwide. We encourage readers to share this information and engage in respectful discussion about the importance of vaccination during pregnancy.