Importance of pre-pregnancy and pregnancy iron status: can long-term weekly preventive iron and folic acid supplementation achieve desirable and safe status?

Most women worldwide enter pregnancy without adequate iron reserves or are already iron deficient. Estimates of iron needs during pregnancy are markedly reduced when iron reserves are available. The needs of absorbed iron to correct mild to moderate anemia in the last two trimesters are estimated. Pre-pregnancy and prenatal weekly supplementation can improve iron reserves effectively and safely, preventing excess iron and favoring better pregnancy outcomes. We explain how the weekly supplementation idea was developed, why current hemoglobin norms may be inadequately high (especially in pregnancy), and why excess iron as recommended by many agencies for developing populations can be undesirable.