Influenza and pregnancy in the United States: before, during, and after 2009 H1N1.

Because pregnant women were recognized to be at increased risk for influenza-associated complications, special considerations for this population were included as part of preparedness efforts before the 2009 H1N1 pandemic. We review data available before the pandemic on influenza and its treatment and prevention during pregnancy. We also review pandemic preparedness efforts aimed at pregnant women and how these efforts served as a foundation for recommendations during the pandemic. Data on 2009 H1N1 influenza in pregnant women and their infants are summarized, and the application of these data to recommendations for pregnant women in future influenza seasons and pandemics is discussed.