Low levels of vitamin B12 may put women at a higher risk of giving birth to children with certain birth defects, new research suggests.

Findings published in the journal Pediatrics show that mothers-to-be with the lowest levels of B12 were 2.5 times most likely to have a baby with brain or spinal cord defects, compared to those with the highest levels.

Lead investigator Dr. James L. Mills of the National Institute of Child Health and Development suggested vegetarians and vegans may be most at risk of having low levels of the vitamin.

Because B12 is found primarily in milk, meat, poultry and eggs, it may be necessary for these women to take nutritional supplements before they conceive.

“Our results offer evidence that women who have adequate B12 levels before they become pregnant may further reduce the occurrence of this class of birth defects,” Mills said.

Women of childbearing age are already recommended to take nutritional supplements containing folic acid to help avoid birth defects.