Birth defects of the neural tube in humans view available hint(s) birth defects of the neural tube in humans are reduced from about 6% without folic acid supplements in the periconception interval to about 1% when the supplements were taken are not affected by nutritional considerations during pregnancy can be prevented by ingestion of more vitamin a during the periconception interval result from excess sodium in the pregnant woman's diet are typically seen in 10-20% of male babies born in well-developed countries