Anna Wald, MD, MPH reviewing Ludvigsson JF et al. Ann Intern Med 2016 Sep 20.

Even when influenza vaccine was administered during the first 8 weeks of pregnancy, no excess risk for congenital malformations was seen in this Swedish cohort study.

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 malformations in children born to women who received the vaccine compared with risk for malformations in unexposed siblings showed similar results. Analyses focused on congenital heart disease, limb deficiency, and oral cleft defects also did not show an elevated risk in offspring born to women vaccinated during pregnancy.

CITATION(S):

Ludvigsson JF et al. Risk for congenital malformation with H1N1 influenza vaccine: A cohort study with sibling analysis. Ann Intern Med 2016 Sep 20; [e-pub]. 

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