Flu in pregnancy 'may raise bipolar risk for baby'

Flu during pregnancy may increase the risk of the unborn child developing bipolar disorder later in life, research suggests.

A study of 814 expectant women, published in JAMA Psychiatry, showed that infection made bipolar four times more likely, BBC reports.

The overall risk remained low, but it echoes similar findings linking flu and schizophrenia.

Experts said the risks were small and women should not worry.

Bipolar leads to intense mood swings, which can last months, ranging from depression and despair to manic feelings of joy, overactivity and loss of inhibitions.

Researchers at the Columbia University Medical Center identified a link between the condition, often diagnosed during late teens and twenties, and experiences in the womb.

In their study looking at people born in the early 1960s, bipolar disorder was nearly four times as common in people whose mothers caught flu during pregnancy.

The condition affects about one in 100 people. The lead researcher, Prof Alan Brown, estimated that influenza infection during pregnancy could lead to a 3-4% chance of bipolar disorder in the resulting children.

However, in the vast majority of cases of bipolar disorder there would no history of flu.