What is the folic acid dosage considered for women with a previous NTD?

The recommendation for women with a previous neural tube defect (NTD) during pregnancy is to take a higher dose of folic acid to reduce the risk of recurrence in future pregnancies. Specifically, the guideline suggests that these women should consume 4000 mcg (or 4 mg) of folic acid daily, starting at least one month before conception and continuing through the first trimester. This higher dosage is significantly above the standard recommendation for the general population, which is typically 400 mcg (0.4 mg) daily, and is based on evidence demonstrating that elevated folic acid levels can greatly decrease the risk of NTDs in at-risk individuals.

The lower doses provided in the other options would not offer the same level of protective benefit for women who have experienced a previous NTD, making them inappropriate for this specific scenario. The insistence on this higher folic acid dosage forms an essential part of the preconception care planning for women with a history of neural tube defects.