Maternal safety outcomes of respiratory syncytial vaccination during pregnancy with a large-scale database

This retrospective cohort study evaluated the risk of maternal safety outcomes, including preterm birth, following prefusion F protein (RSVpreF) during pregnancy compared with an unvaccinated cohort using large-scale real-world data. Propensity score matching was performed to compare the risks of preterm delivery, hypertensive disorder of pregnancy (HDP), gestational diabetes (GDM), oligohydramnios, placental abruption, intrauterine growth restriction (IUGR), and intrauterine fetal death (IUFD) to calculate the odds ratio (OR). Following the propensity score matching, 11,265 and 11,265 pregnant women with and without RSVpreF vaccination were included, respectively. After matching, the ORs in the vaccinated group compared with the unvaccinated group were 0.98 [0.84-1.14], p = 0.789; 1.01 [0.96-1.08], p = 0.644; 0.98 [0.90-1.06], p = 0.570; 0.77 [0.63-0.95], p = 0.015; 0.99 [0.77-1.27], p = 0.949; 0.94 [0.86-1.03], p = 0.189; and 0.68 [0.38-1.22], p = 0.189 for pre-term delivery, HDP, GDM, oligohydramnios, placental abruption, IUGR, and IUFD, respectively. Maternal RSV vaccination did not increase the risk of selected maternal outcome events. However, further safety monitoring with larger sample size is required to detect rare events or small risk differences.