Many studies have shown that periconceptional folic acid supplementation significantly reduces the incidence of neural tube malformations. Neural tube defects (NTDs), also known as neural tube malformations, are serious malformations of the central nervous system, and the main types of manifestations include anencephaly, crural bifida, and brain enlargement. It seriously affects the life, health, intelligence and quality of life of the affected children, and brings great mental and economic burden to their families. Under normal circumstances, the neural tube of the human embryo begins to close at 5 weeks of pregnancy and finishes closing at 6 weeks of pregnancy. If the level of folic acid in the mother is insufficient during this period, it will affect the closure of the neural tube of the fetus, resulting in neural tube defects. The human body cannot synthesize folic acid and can only obtain it through exogenous sources. Folic acid is widely found in green vegetables, citrus fruits, beans, nuts, animal liver and other foods. Pregnant women are highly susceptible to folic acid deficiency due to changes in physiological metabolism, elevated demand for folic acid compared to normal people, and reduced absorption. Therefore, the 2017 Guidelines for Periconceptional Folic Acid Supplementation for the Prevention of Neural Tube Defects recommend that folic acid supplementation should be started from the 3 months before possible pregnancy or conception, with a daily supplement of 0.4mg-0.8mg of folic acid to the 3rd trimester of pregnancy, because the body’s demand for various nutrients is correspondingly elevated after pregnancy, so it is generally recommended that it can be taken until the end of pregnancy in the clinic. For women with high risk factors, such as women with diabetes, obese women, women suffering from intestinal malabsorption disease, the amount of daily folic acid supplementation is correspondingly higher, 0.8-1mg of folic acid supplementation per day, for other kinds of high-risk factors of women, the amount of daily folic acid supplementation has been correspondingly higher. Are there any side effects of folic acid supplementation? Any substance is best in moderation, and too much folic acid supplementation can have adverse effects on the body. High-dose folic acid supplementation may mask the symptoms of vitamin B12 deficiency, thus delaying diagnosis and treatment, and long-term high-dose folic acid supplementation may increase the risk of colon cancer. In contrast, short-term, moderate folic acid supplementation in peri-pregnant women is very unlikely to cause any harm to the body.