The 2009 pandemic influenza A/H1N1 developed as a novel swine influenza which caused more diseases among younger age groups than in the elderly. Severe hypoxemic respiratory failure from A/H1N1 pneumonia resulted in an increased need for ICU beds. Several risk groups were identified that were at a higher risk for adverse outcomes. Pregnant women were a particularly vulnerable group of patients The CDC reported on the first ten patients with severe illness and acute hypoxemic respiratory failure associated with A/H1N1 infection, none of whom were pregnant, but they noticed that half of the patients had a pulmonary embolism.
