Folic acid TT type refers to the MTHFR (methylenetetrahydrofolate reductase) gene fragment C677T locus related to folate metabolism, and the test results in TT genotype, which is inborn and determined by congenital hereditary factors. Methylenetetrahydrofolate reductase is a key enzyme involved in folate metabolism, which can affect homocysteine clearance, DNA synthesis and repair, and is an important factor in causing infertility, miscarriage, and inducing birth defects in newborns. TT genotype at the C677T locus suggests a high-risk gene for folate metabolism, representing a defective ability to utilize folate metabolism. The cause at the genetic level cannot be addressed at the root cause and can only be addressed through acquired folic acid supplementation to reduce the risk of birth defects in newborns. For patients with high risk of folic acid metabolism, it is generally recommended to start folic acid supplementation 3 months prior to pregnancy preparation and continue until the end of pregnancy, under the guidance of a physician. Along with folic acid supplementation during the preparation period or pregnancy, you should consume more folic acid-rich foods, such as green leafy vegetables and fresh fruits. At the same time, you should develop healthy lifestyle habits, maintain a reasonable body weight and take comprehensive measures to reduce the rate of miscarriage and the risk of birth defects in newborns, but the intake of folic acid should not be excessive and should be used in accordance with medical advice.