Pre-Birth Exposure to 1918 Flu Raised Heart Risks, Study Finds

Oct. 2 -- THURSDAY, Oct. 1 (HealthDay News) -- People exposed to the deadly 1918 Spanish flu pandemic while still in their mother's womb were about 20 percent more likely to have heart disease 60 years later, a new study has found.

The flu outbreak in 1918 killed 20 million to 40 million people worldwide, including 500,000 in the United States. That flu, like the current H1N1 swine flu pandemic, began as a mild disease, but it then came back in a much more lethal form. What the current H1N1 flu will do is unknown, but so far its genetics have not changed and there is a vaccine to protect against it, researchers say.

That's especially good news for pregnant women.

"There are long-term effects of being exposed prenatally to flu," said lead researcher Caleb Finch, director of the Gerontology Research Institute at the University of Southern California. "There is a danger to the fetus from exposure to maternal flu that has shown up 60 years later from the 1918 influenza epidemic."

Why exposure to flu in the womb has this effect is not known, Finch said, but he added that it's "a likely outcome of maternal stress."

Maternal stress increases a number of developmental problems, including the risk for autism and schizophrenia, Finch said.

Whether these same effects can be traced to other flu strains also is unknown, he said. "Each flu is different, and the 1918 epidemic remains the most virulent," he said. "Subsequent epidemics have not been as severe. This could have been something unique to that, but we can't tell. It took 60 years to find this out."

The findings are reported in the Oct. 1 issue of the Journal of Developmental Origins of Health and Disease.

For the study, Finch's team collected data on 101,068 people born around the time of the 1918 flu pandemic -- specifically, between 1915 and 1923. Information came from national surveys conducted from 1982 to 1996, when most participants were 63 to 78 years old.