RSV Vaccine in Pregnancy Shows Similar Safety Results
Interim U.S. data from five health plans found comparable maternal and infant safety outcomes for vaccinated and unvaccinated pregnancies.
Updated on Nov. 4, 2026 in Pregnancy
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Interim data presented at IDWeek showed similar maternal and infant safety outcomes for vaccinated and unvaccinated pregnancies across two RSV seasons. Vaccinated pregnancies also showed a slightly lower rate of preterm birth.
Why it matters
The findings add real-world evidence on the safety of maternal RSV vaccination across a large population. Because the interim analysis was not designed to give a definitive safety conclusion, the results will be further evaluated in a final analysis.
Preterm birth occurred in 4.7% of vaccinated pregnancies versus 6.3% of unvaccinated pregnancies, while hypertensive disorders occurred in 16.8% versus 15.8%. The comparison covers 29,486 vaccinated pregnancies matched 1:1 with 17,297 unvaccinated pregnancies.
The players
IDWeek
An annual scientific meeting focused on infectious diseases, where the interim findings were presented.
The details
Researchers matched vaccinated and unvaccinated pregnancies by health plan, gestational age, year and quarter of pregnancy start, evidence of immunocompromise or hypertensive disorders, and propensity score. They compared pregnancy, maternal, and infant outcomes between the matched groups, with pregnancies identified between Sept. 22, 2023, and Aug. 14, 2025.
Timeline
Sept. 22, 2023: Vaccinated pregnancy identification window opens.
Aug. 14, 2025: Vaccinated pregnancy identification window closes.
Nov. 4, 2026: Interim data presented at IDWeek.
Health Landscape
The interim results are part of ongoing monitoring of maternal RSV vaccination, with a final analysis planned using more sophisticated epidemiologic methods. Until that analysis is complete, the study cannot be treated as a definitive safety determination.
Pregnant people weighing RSV vaccination can note that interim data showed similar maternal and infant safety outcomes for vaccinated and unvaccinated pregnancies. The study was not designed to give a definitive safety answer, so decisions should be made with a clinician.
The takeaway
Interim evidence so far is reassuring on maternal and infant safety for vaccinated pregnancies, but a final analysis is still needed before drawing firm conclusions. Pregnant people should discuss RSV vaccination with their healthcare provider.
What happens next
Results will be incorporated into continued monitoring and a final analysis using additional, more sophisticated epidemiologic methods.
Further reading
Explore more on Pregnancy health and safety topics.
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Would you feel comfortable getting an RSV vaccine during pregnancy to protect your baby?
