A 2017 CDC study links miscarriage to flu vaccines, particularly in the first trimester. Pregnant women vaccinated in the 2010/2011 and 2011/2012 flu seasons had two times greater odds of having a miscarriage within twenty-eight days of receiving the vaccine. In women who had received the H1N1 vaccine in the previous flu season, the odds of having a miscarriage within twenty-eight days were 7.7 times greater than in women who did not receive a flu shot during their pregnancy.80
