Mothers-to-be who have influenza during pregnancy may increase the risk of bipolar disorder in their offspring, researchers in South Africa said. Raveen Parboosing of Albert Luthuli Central Hospital in Durban, South Africa, and colleagues used the Child Health and Development Study, Kaiser Permanente and county healthcare databases, which included 92 confirmed cases of bipolar disorder confirmed 214 study participants and 722 control participants. The study, published in the journal Psychiatry, found a nearly four-fold increase in the risk of bipolar disorder after exposure to maternal influenza at any time during pregnancy. "The findings suggest gestational infection with the influenza virus confers a nearly four-fold increased risk of bipolar disorder in adult offspring," the researchers wrote in the study. "If confirmed by studies in other birth cohorts, these findings may have implications for prevention and identification of pathogenic mechanisms that lead to bipolar disorder. Further work, including serologic -- blood serum -- studies for maternal influenza antibody in archived specimens from this cohort is warranted." Bipolar disorder or bipolar affective disorder, also known as manic-depressive disorder or manic depression, is a psychiatric diagnosis for individuals who experience episodes of a frenzied state known as mania, typically alternating with episodes of depression.