1. According to the “Guidelines for Preconception and Pregnancy Care (First Edition)” issued by the Obstetrics and Gynecology Branch of the Chinese Medical Association, 1. First trimester: supplementation with 400-800 mcg/day of folic acid, or an evidence-based multivitamin containing folic acid. Pregnant women with previous neurological defects require folic acid supplementation of 4 mg/day. 2. After pregnancy: Continue supplementation with 400-800 mcg/day of folic acid until the third trimester, or a multivitamin containing folic acid if available. 2. If you want to use the medication precisely, you need to do the test of folic acid metabolism gene and assess the specific medication according to the risk: Test result 3 months before pregnancy 12 weeks of pregnancy 13-40 weeks of pregnancy Normal 400 mcg/day 400 mcg/day Dietary supplementation Low risk 400 mcg/day 400 mcg/day 400 mcg/day Moderate risk 400 mcg/day 800 mcg/day 400 mcg/day High risk 800 µg/day 800 µg/day 400 µg/day