Taking multivitamins during pregnancy may protect children from cancer, a study suggests.

Researchers in North America have found that women who take vitamins while pregnant cut their children's risk of neuroblastoma, a kind of nervous system tumour, by one third.

The scientists were unable to say which vitamin in particular protected the children.

[It] is the most common tumour diagnosed in infants

Professor Andrew Olshan

However, they pointed to other studies which have suggested that multi-vitamins during pregnancy protects children from childhood leukaemias and brain tumours.

Professor Andrew Olshan and colleagues at the University of North Carolina and scientists at the University of Texas looked at 538 children with neuroblastoma in 139 hospitals in Canada and the United States.

They compared them to 504 comparable children without neuroblastoma and asked the mothers whether they took vitamins before, during and after pregnancy.

They also examined other possible health-related factors and education and income.

'Clear link'

Professor 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.

But he said neuroblastoma "is the most common tumour diagnosed in infants and is usually diagnosed in children under age three".

He added: "Typically, fewer than 50% of affected patients live five years following diagnosis."

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.

Neuroblastoma accounts for 8% of all childhood cancers, and is usually diagnosed in the first few years of life.

The disease may start in developing cells in the adrenal glands or lymph nodes in the abdomen or chest.

It spreads quickly, and more than half of all patients are not diagnosed until satellite tumours have developed in the bone marrow or bone.

More than 60% of all neuroblastoma patients have an advanced stage, high-risk form of the disease that is often resistant to treatment and usually leads to death within two years.

Despite advances in treatment, only 25% to 30% of children with advanced neuroblastoma can be cured.