Identifying women who might benefit from higher doses of folic acid in pregnancy

Question: One of my epileptic patients who takes carbamazepine is planning to become pregnant. She told me that Motherisk advised her to take 5 mg of folic acid daily until the end of the first trimester. Are there other women who need more than the regular dose of folic acid included in prenatal vitamins? Answer: Women who are at high risk of having babies with neural tube defects and who would benefit from higher doses of folic acid include those with certain folate-enzyme genotypes, previous pregnancies with neural tube defects, diabetes, malabsorption disorders, or obesity, or those who take antifolate medications or smoke. Such women should take 5 mg/d of folic acid for the 2 months before conception and during the first trimester.