Pregnant women, already urged to take multivitamins to prevent birth defects such as spina bifida, may also be protecting their babies against cancer, researchers said Friday.
They found that women who took vitamins during pregnancy cut their children's risk of neuroblastoma, a kind of nervous system tumor, by 30 percent to 40 percent.
The U.S. and Canadian researchers could not pinpoint which vitamin was responsible, but said other studies have suggested vitamin use during pregnancy may protect against childhood leukemias and brain tumors.
"Neuroblastoma ... is the most common tumor diagnosed in infants and is usually diagnosed in children under age 3," Dr. Andrew Olshan, a professor of epidemiology at the Univeristy of North Carolina who led the study, said in a statement.
"Typically, fewer than 50 percent of affected patients live five years following diagnosis."
In the United States, 9.1 out of every 1 million children develop neuroblastoma.
Olshan's team, working with colleagues at the M.D. Anderson Cancer Center at the University of Texas in Houston, the U.T. Health Science Center in San Antonio and the University of Minnesota, looked at 538 children with neuroblastoma in 139 U.S. and Canadian hospitals already taking part in a cancer registry.
They compared them to 504 comparable children without neuroblastoma, and asked the mothers about whether they took vitamins before, during and after pregnancy and looked at other possible health-related factors. They took into account education and income and other possible influences.
Olshan said the findings clearly suggest women who took vitamins were less likely to have children who developed neuroblastoma. He said more study needs to be done, especially to pinpoint which vitamins may be responsible.
Pregnant women or women who may conceive are advised to take a daily vitamin containing folic acid, which can protect against spina bifida and related defects of the spinal cord.
Many multivitamins contain high levels of vitamin A which, if too much is taken, can cause birth defects, so women are advised to study labels carefully and consult their doctors.