Influenza in Pregnant Women and Bipolar Disorder Risk in Offspring

Prenatal infections have been associated with subsequent risk for schizophrenia, and, more recently, up to fourfold increases in bipolar disorder risk have been reported among offspring whose mothers were clinically diagnosed with influenza while pregnant. To more precisely examine these links, investigators used serological evidence of influenza exposure from maternal samples obtained from virtually all pregnant women in the Northern California Kaiser Permanente system who gave birth between 1959 and 1966.

Information on offspring was obtained by follow-up letters mailed in 2009–2011 to 6981 living mothers and 13,009 cohort members and from Kaiser Permanente and Alameda County records. Of the 448 potential cases of major psychiatric disorde…