Whether or not oral folic acid 5mg per day has any effect on a pregnant woman should depend on the situation. If there is no indication for overdose, taking this dose orally may reduce the absorption of zinc, which may affect the development of the fetus, and may also cause nausea, abdominal distension and other discomforts. For women who have given birth to a fetus with neural tube defects, or for women with one spouse with neural tube defects, or for women with hyperhomocysteinemia, it is recommended that they take 5 mg/d of oral folic acid from the time they find out they are pregnant, or for one month prior to conception, until the third trimester of pregnancy. For other women it is generally recommended to take 0.4~0.8 mg of oral folic acid per day, starting from the third trimester of pregnancy until the third trimester of pregnancy, if there is no indication to increase the oral folic acid, excessive oral folic acid can affect the absorption of zinc, affecting the growth and development of the fetus, and sometimes cause nausea, vomiting, abdominal distension and other digestive tract symptoms in pregnant women. It is recommended that women who are preparing for pregnancy take oral folic acid under the guidance of an obstetrician before supplementing with folic acid based on their previous fertility.