Aug. 2, 2004 -- Babies whose mothers are exposed to the flu virus during pregnancy may face a higher risk of developing schizophrenia in later life, a new study suggests.

Although many previous studies have linked prenatal exposure to influenza with adult schizophrenia, researchers say this is the first study based on laboratory evidence of flu exposure during pregnancy.

The study showed that the risk of schizophrenia was three times higher among adult children exposed to influenza during the first half of pregnancy compared with those who had not been exposed. But there was no increase in risk associated with influenza exposure during the second half of pregnancy.

"These findings represent the strongest evidence thus far that prenatal exposure to influenza plays a role in schizophrenia," says researcher Ezra Susser, MD, DrPH, chairman of the department of epidemiology at the Mailman School of Public Health at Columbia University, in a news release. "Although the findings may ultimately have implications for prevention, we strongly caution against making any public health policy recommendations until these links have been confirmed through further study."

Schizophrenia is a severe mental disorder that affects about 1% of the population. The exact cause is unknown, but it's likely caused by a combination of factors such as heredity, problems in the way the brain develops before birth, and problems experienced during pregnancy that may affect the development of the baby's nervous system, including exposure to a virus.