Mechanism of teratogenicity of antiepileptic drugs: Fetal teratogenicity caused by antiepileptic drugs may be related to folic acid metabolism, and animal experiments have shown that deficiency of folic acid can lead to a significant increase in teratogenicity in the offspring. Since most antiepileptic drugs can lead to decreased absorption of folate, especially enzyme-induced antiepileptic drugs can interfere with folate metabolism, resulting in a significant decrease in maternal serum folate. Therefore, perinatal folic acid supplementation may reduce neural tube development defects. Another reason for increased teratogenicity caused by antiepileptic drugs is the direct toxicity of the drugs, such as the breakdown products of phenytoin sodium and epoxide, a metabolite of carbamazepine, which can produce teratogenic effects by binding to macromolecules in the embryo. In addition phenobarbital, sodium phenytoin, and carbamazepine can inhibit delayed potassium channels, induce cardiac arrhythmias, and lead to altered hemodynamics, which can cause cleft lip, limb defects, and growth retardation. Intrauterine exposure to antiepileptic drugs also leads to abnormalities in chromosomal structure, resulting in increased teratogenicity. The mechanism by which sodium valproate causes fetal neural tube defects may be that valproate inhibits various enzymes, including glutamate formylase, which converts folate, thereby interfering with folate production, in addition to its induction of abnormal susceptibility genes leading to an increased incidence of teratogenesis. Women should take precautions during pregnancy: 1. To determine the need for oral antiepileptic drugs, if they have been seizure-free for 2-4 years, the risk of recurrence is 20-60%, so this group of patients can be carefully considered for discontinuation of drugs before pregnancy. 2. For patients requiring antiepileptic drugs, monotherapy should be administered based on seizure type as much as possible. 3. The dose of antiepileptic drugs should be given at the minimum effective therapeutic dose. 4. Apply less teratogenic and safer class C drugs whenever possible. 5. Antiepileptic drugs should be given in divided doses during pregnancy or with extended-release tablets to avoid excessive fluctuations in blood levels. 6, must take folic acid before pregnancy, the daily dose of no more than 0.5mg is appropriate. 7. Never stop antiepileptic drugs suddenly in pregnancy, otherwise it will lead to seizures or even the occurrence of persistent status epilepticus.