The effect of missing 1 day of folic acid is not significant. Under normal circumstances, women should start taking folic acid 3 months before preparing for pregnancy, and should take it until 3 months after pregnancy. This drug is mainly used to prevent fetal neural tube abnormalities. If a pregnant woman has folic acid metabolism disorder or a history of bad pregnancy and delivery, she needs to take 0.8mg of folic acid, which should be taken 3 months before pregnancy and should be taken until delivery. Therefore, the dose of the drug is 1 times larger than that of the normal pregnancy population, and the time taken is longer, so that the incidence of fetal neural tube malformation can be effectively reduced.