The biggest culprit is white flour. Hulling the wheat to make it 'pretty' also makes it nutritionally terrible.

Specific neural cord defects that occur early in the first few weeks of pregnancy, before women are aware they are pregnant, are believed to be due to low B9 - folate.

Certainly I believe that pollutants in general are likely involved too.

Vaccines, easiest way to turn a mother antivax? Nearly losing a child to a hep b vaccine.