Oral folic acid should be started before pregnancy. Women should take oral folic acid routinely 3 months prior to pregnancy preparation with the aim of preventing the occurrence of fetal neural tube abnormalities. A folic acid bioavailability test can be performed before taking folic acid, and the amount of oral folic acid and the duration of folic acid intake can be decided based on the test results. In case of mild deficiency, folic acid should be taken at normal dose starting 3 months before pregnancy and also at normal dose after pregnancy, and after 13 weeks of pregnancy folic acid should be stopped and can be supplemented from food. For moderate or severe folate deficiency, take additional oral folic acid before pregnancy, and after pregnancy, also at regular doses, and reduce the dose appropriately until 13 weeks of pregnancy, until the full term of pregnancy.