[A study on risk factors of neural tube defects].

One hundred and twenty-three cases with neural tube defects collected during 1991 to 1993 from 12 hospitals with birth defect surveillance in Hebei Province, and their pair-matched controls were analyzed with single and multiple conditional logistic regression to study the effects of food and drinking water on occurrence of neural tube defects. Results showed factors contributing to neural tube defects were maternal previous history of birth defects, much consumption of dried and pickled vegetables during pregnancy, too much nitrate content in drinking water (containing more than 10 mg nitrogen per liter of water), less consumption of meat, eggs, and beans in their diet.