Inactivated influenza vaccine is recommended for routine use in high-risk individuals in the United States, including women who will be in the second or third trimesters of pregnancy. The basis for this recommendation is the high risk of exposure and disease due to influenza viruses in pregnant women, as well as the impact of influenza virus infection on the fetus and infant. Historical data from the influenza pandemics of 1918 and 1957 illustrate the potential risks of this infection in pregnant women and their fetuses. Prospective studies have demonstrated higher cord antibody levels to influenza in babies born to mothers immunized during pregnancy, and a delay in the onset and decrease in severity of babies born with higher antibody levels. Increased influenza vaccine use during pregnancy has the potential to benefit both the woman and her infant.