COVID-19 Vaccination During Pregnancy Significantly Reduces Preeclampsia Risk

COVID-19 infection during pregnancy is linked to a substantially increased risk of preeclampsia, a serious pregnancy complication. However, recent research indicates that vaccination against COVID-19, particularly with a booster dose, offers significant protection against developing this condition. A major study by the INTERCOVID Consortium found a 33% reduction in preeclampsia risk among vaccinated pregnant women, with even greater benefits – a 42% reduction – observed in those with pre-existing health conditions like diabetes, hypertension, or thyroid disorders.

Understanding Preeclampsia and COVID-19

Preeclampsia affects 3-8% of pregnancies globally and is a leading cause of maternal and neonatal illness and death. Research demonstrates that contracting COVID-19 whereas pregnant increases the risk of developing preeclampsia. In fact, unvaccinated pregnant women with COVID-19 face a 78% higher risk compared to a 45% increased risk for those who are infected but vaccinated. The origins of preeclampsia remain unclear, but inflammation and vascular dysfunction are known contributing factors – mechanisms that also play a role in COVID-19 infection.

Key Findings from the INTERCOVID Consortium Study

Researchers from the INTERCOVID Consortium analyzed data from 6,527 pregnant women across 18 countries between 2020 and 2022. Their findings, published in eClinicalMedicine, revealed:

• COVID-19 infection during pregnancy was associated with a 45% increased risk of preeclampsia, rising to 78% among unvaccinated women.
• Vaccination reduced the overall odds of preeclampsia amongst women receiving a booster dose by 33% (statistically significant).
• Among women with pre-existing health conditions, vaccination with a booster cut preeclampsia risk by 42% (statistically significant).
• The protective effect of vaccination remained consistent even after accounting for other factors, suggesting benefits beyond preventing COVID-19 infection itself.
• Vaccinated women also experienced lower rates of preterm delivery, maternal and perinatal morbidity, and mortality.
• A booster dose was associated with a 33% reduction in preterm birth, a 32% reduction in maternal morbidity and mortality, and a 29% reduction in severe perinatal morbidity and mortality – all statistically significant.

Beyond Infection Prevention: Broader Benefits of Vaccination

The study suggests that COVID-19 vaccination may influence the biological pathways involved in preeclampsia development, potentially offering a broader immunological or vascular benefit. Researchers, including experts from Northwestern University Feinberg School of Medicine and the University of Oxford, believe this aligns with growing evidence that some vaccines may have beneficial “non-specific” effects on immune regulation.

Implications for Maternal Health

“These results go beyond the known benefits of COVID-19 vaccination in pregnancy,” said Professor José Villar, senior co-author of the study and Principal Investigator of the INTERCOVID consortium from the Nuffield Department of Women’s & Reproductive Health, University of Oxford. “We now have evidence that maternal vaccination may influence pathways involved in preeclampsia development, suggesting a broader immunological or vascular benefit of vaccination.”

According to Jagjit S. Teji, MD, a neonatologist at Lurie Children’s and Clinical Assistant Professor of Pediatrics at Northwestern University Feinberg School of Medicine, “Our results support the importance of strengthening COVID vaccination programs during pregnancy, emphasizing boosters and ensuring that pregnant people across the world have equitable access to the vaccine.”

Staying Informed and Protected

The Preeclampsia Foundation and leading medical societies like the American College of Obstetricians and Gynecologists continue to recommend COVID-19 vaccination for pregnant individuals. Prevention remains the best strategy, and vaccination is a crucial tool in protecting both maternal and infant health.