Pregnancy-Related Mortality Resulting From Influenza in the United States During the 2009-2010 Pandemic.

OBJECTIVE To estimate the burden of pregnancy-related mortality resulting from influenza A (H1N1)pdm09 virus infection during the 2009-2010 pandemic influenza season. METHODS Data from the Centers for Disease Control and Prevention's Pregnancy Mortality Surveillance System were used to identify women whose death during or shortly after pregnancy was attributed or likely attributed to the influenza A (H1N1)pdm09 virus from April 15, 2009, through June 30, 2010. We report the characteristics of these women and enumerate cases resulting in death as the pandemic began, peaked, and resolved. RESULTS During the pandemic season, we identified 915 pregnancy-related deaths and 4,911,297 live births. Seventy-five (8.2%) women died as a result of confirmed influenza A (H1N1)pdm09 infection deaths and 34 (3.7%) women as a result of possible influenza A (H1N1)pdm09 infection deaths. The pregnancy-related mortality ratio for confirmed and possible (combined) influenza A (H1N1)pdm09 infection deaths was 2.2 per 100,000 live births. Most deaths occurred during the 2009 calendar year with the peak of the distribution of deaths over time occurring in October 2009. CONCLUSION Twelve percent of pregnancy-related deaths were attributed to confirmed or possible influenza A (H1N1)pdm09 infection during the 2009-2010 pandemic season. Because prediction of pandemics is difficult, planning for prevention of influenza and care for those women affected are critical for preventing associated severe maternal morbidity and mortality. LEVEL OF EVIDENCE III.