Hello, welcome to Healthcaremagic. 400 mcg is equivqlent to 4 mg. Folic acid deficiency
can lead to neural tube defects. The best way to prevent neural defects is to take the recommended 400 micrograms of folic acid daily for one month before conception and during the first three months of pregnancy
. However for pregnant women the dosage recommended is 600 to 800 mcg as the requirement is more. So your doctor would inform you about the dosage required and when to increase it. Wish you good health.