Influenza Vaccine Protects Pregnant Women and Their Fetuses

Questions about the safety of influenza vaccine during pregnancy linger. Using nationwide registries before, during, and after the 2009 H1N1 pandemic, investigators in Norway evaluated risk for influenza infection in vaccinated and unvaccinated pregnant women as well as risk for fetal death after 12 weeks' gestation in vaccinated women and those infected during pregnancy.

Among the 113,331 women who became pregnant during the pandemic, 492 fetal deaths occurred compared with 410 fetal deaths among 99,539 women who conceived outside the pandemic period (4.3 vs. 4.1 fetal deaths/1000 births). Risk for fetal death among women with clinical diagnoses of influenza was almost twice that among uninfected women (hazard ratio, 1.90). Risk for influen…