The exact cause of IgA deficiency is unknown and may result from infection and environmental exposures and also has a familial component. IgA is critically important for mucosal immunity, particularly in the sinopulmonary and gastrointestinal systems. Recurrent infection, allergic reactions, and autoimmunity are common complications. Autoantibodies to IgA could result in severe allergic transfusion reactions, which could pose a major risk to the pregnant woman with IgA deficiency.