Different populations have different supplementation methods. The Guidelines for the Prevention of Neural Tube Defects through Folic Acid Supplementation in the Periconceptional Period (2017) published in China recommend the following: 1. Women without risk factors: 0.4 mg or 0.8 mg of folic acid daily from the time of potential pregnancy or at least 3 months before conception until the third month of pregnancy. 2. Women with a history of neural tube defects: It is recommended to take 4mg of folic acid daily starting from at least 1 month before possible pregnancy or conception until the 3rd month of pregnancy. Since 4mg is not available in China and 5mg is available, 5mg of folic acid can also be given daily. 3. Women with one spouse suffering from neural tube defects or with previous history of neural tube defects in the male partner: It is recommended to take 4mg of folic acid daily from the time of potential pregnancy or at least 1 month before pregnancy until the 3rd month of pregnancy. Since 4mg is not available in China and 5mg is available, 5mg of folic acid can also be given daily. 4.Women with congenital hydrocephalus, congenital heart disease, cleft lip and palate, limb defects, urinary system defects, or family history of these defects, or a history of neural tube defects in the first or second degree of consanguinity: 0.8-1.0mg of folic acid daily from the time of potential pregnancy or at least 3 months before conception until the third month of pregnancy. 5. Women with diabetes, obesity or epilepsy: 0.8-1.0 mg of folic acid daily from the time of potential pregnancy or at least 3 months prior to conception until 3 months of pregnancy. Women taking drugs that increase the risk of fetal neural tube defects: 0.8-1.0 mg of folic acid daily until 3 months of gestation is recommended for women taking carbamazepine, valproic acid, phenytoin sodium, paracetamol, phenobarbital, metformin, methotrexate, pyridoxine, methotrexate, aminopterin, clofazimine, etc. from the time of possible pregnancy or at least 3 months before pregnancy. . 7. Women with gastrointestinal malabsorption disorders: 0.8-1.0 mg of folic acid daily from the time of potential pregnancy or at least 3 months before conception until the third month of pregnancy. 8.Personalized supplementation: Women with the following conditions may increase the supplementation dose or extend the duration of preconception supplementation as appropriate: ① living in the north, especially in rural areas in the north; ② low consumption of fresh vegetables and fruits in the diet; ③ low blood folate level; ④ TT genotype at MTHFR677 locus; ⑤ short preparation time for pregnancy. Note: 1. This guideline recommends 0.8mg folic acid compared to the previous routine supplementation of 0.4mg folic acid. 2. Multivitamins without folic acid have no preventive effect on neural tube defects. 3.While taking folic acid supplementation, you should eat more folic acid-rich foods, adopt a healthy lifestyle and maintain a reasonable body weight. 4.If you have the condition, you can do MTHFR monitoring and choose different doses of folic acid supplementation precisely according to your genotype. 5.Neural tube abnormality, also known as neural tube defect, is a serious malformation disease, the neural tube is the central nervous system of the fetus. On the 15th to 17th day of embryo, the nervous system starts to develop, until about the 22nd day of embryo, the two sides of the neural fold start to close to each other, forming a tube called neural tube, its front end is called neural tube anterior foramen, and the tail end is called neural tube posterior foramen, the anterior foramen and posterior phase close when the embryo is on the 24th, 25th and 26th day. Fetal neural tube anomalies are mainly manifested as anencephaly, cerebral bulge, cerebrospinal meningeal bulge, spina bifida/recessive spina bifida, cleft lip and cleft palate, etc.