['Universal prenatal daily supplementation with iron (60-120mg iron) plus folic acid (0.4mg), as recommended by INACG/WHO/UNICEF, prevents anemia where iron deficiency is prevalent but may be excessive for non-anemic women. Weekly supplementation with 120mg iron plus various amounts of folic acid similarly prevents significant anemia.', 'Determine, in non-anemic pregnant women, if oxidative stress is produced by recommended daily or weekly supplementation schemes.', '100 non-anemic pregnant women, 30% iron-deficient at week 20, were randomly supplemented daily followed by weekly, each for 8 weeks, or in reversed order.', 'With daily supplementation thio-barbituric-acid-reacting-substances (TBARS) increased significantly and high serum ferritin, iron, and excessively elevated hemoglobin occurred near term. During weekly supplementation significant anemia and high iron parameters were prevented, and elevated TBARS declined.'] Do antenatal iron supplements consumed daily produce oxidative stress in contrast to weekly supplementation in Mexican non-anemic women?