Iron status, including hemoglobin, S-ferritin, S-iron, S-transferrin, transferrin saturation and the erythrocyte zinc protoporphyrin/hemoglobin (ZPP:Hb) ratio, was evaluated in 85 healthy iron-supplemented mothers at parturition and in 74 of their term newborn infants. Of the mothers, 17% had a S-ferritin level less than 15 micrograms/l (i.e. depleted iron stores), 9.9% had S-ferritin less than 15 micrograms/l and transferrin saturation less than 15% (i.e. latent iron deficiency), and 2.4% had S-ferritin less than 15 micrograms/l, transferrin saturation less than 15% and Hb less than 120 g/l (i.e. iron deficiency anemia). Newborn infants had higher S-ferritin than mothers: median 128 micrograms/l versus 21 micrograms/l (p less than 0.0001), higher transferrin saturation: 48% vs. 21% (p less than 0.0001), and higher ZPP:Hb ratio: 74 mumol/mol Hb vs. 41 mumol/mol Hb (p less than 0.0001). During the first 5 post-natal days, median S-ferritin rose from 128 to 236 micrograms/l (p less than 0.0001). S-ferritin appeared to be the best single indicator of maternal iron status. Ferritin levels in newborn infants were correlated to levels in mothers (rs = 0.36, p less than 0.01), indicating that fetal iron reserves are dependent on maternal iron stores.