TOPLINE

Pregnant patients who received the maternal bivalent prefusion F subunit-based respiratory syncytial virus (RSVpreF) vaccine late in pregnancy did not have higher risks for preterm birth, stillbirth, or small-for-gestational-age birth weight but had a slightly higher risk for hypertensive disorders of pregnancy.

METHODOLOGY

• Researchers emulated a target trial using data from multiple US health systems to assess whether maternal RSVpreF vaccination in pregnancy affected birth and pregnancy outcomes.
• They included pregnant patients aged 16-49 years with singleton pregnancies between September 2023 and February 2024.
• A total of 13,966 pregnant patients who received the vaccine between 32 and less than 37 weeks of pregnancy were propensity score-matched with an equal number of unvaccinated pregnant patients.
• Researchers compared the risks for preterm birth, stillbirth, small-for-gestational-age birth weight, and hypertensive disorder of pregnancy that occurred during pregnancy and up to 14 days postpartum.

TAKEAWAY

• The risks for preterm birth, stillbirth, and small-for-gestational-age birth weight did not differ between vaccinated and unvaccinated patients.
• Vaccinated pregnant patients had a higher risk for any hypertensive disorder of pregnancy than unvaccinated peers (adjusted risk ratio, 1.13; 95% CI, 1.07-1.19), with higher risks for gestational hypertension and preeclampsia.
• When the analysis was limited to the 21 days after vaccination, the risk for any hypertensive disorder of pregnancy did not differ significantly between groups.

IN PRACTICE

“Our initial RSVpreF safety surveillance shows a largely favorable safety profile for vaccination during pregnancy. This information can be used to counsel pregnant patients as they decide which RSV-prevention strategy to use to protect their newborns and infants,” the researchers of the study wrote.

SOURCE

The study was led by Malini DeSilva, MD, HealthPartners Institute, Bloomington, Minnesota. It was published online on June 18 in Obstetrics & Gynecology.

LIMITATIONS

The study was underpowered to detect the risks for rare outcomes. Data on parity were missing for 9.4% of the patients. Hypertensive disorders were identified using diagnosis codes and were not confirmed with blood pressure readings.

DISCLOSURES

The study received support from the CDC. One author disclosed receiving research support from Pfizer for vaccine-related studies and from many other companies for unrelated work. Another author disclosed receiving research support from AbbVie and Sanofi for unrelated work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.