Fetal Safety of the H1N1 Influenza Vaccine

Given the high complication rates of influenza in pregnant women, vaccination is recommended during pregnancy. To assess whether monovalent AS03-adjuvanted H1N1 influenza vaccine is associated with excess risk for congenital malformations, investigators examined medical records of >40,000 Swedish pregnant women (including >14,000 vaccinated during the first trimester and 7500 during the first 8 weeks of pregnancy) who received pandemic H1N1 influenza vaccine between 2009 and 2011 compared with >19,000 women who were not vaccinated.

Adjusted risk for congenital anomalies was similar among offspring of vaccinated and unvaccinated women (4.97% and 4.78%), regardless of timing of vaccination during pregnancy. A second analysis assessing risk for…