Iron and folate status of 203 pregnant women have been evaluated at 6 months gestation and on the same women and their newborn infants at delivery. The women who had, at 6 months gestation, a Hb level below 11 g/dl were systematically given iron supplements. Iron or placebo were randomly allocated to the other women. At 6 months of pregnancy, one quarter of the women had a Hb level under 11 g/dl but one third had a serum ferritin level below 12 μg/l and more than half had low levels of serum and red cell folate. Iron supplements induced an increase both in Hb levels and in serum ferritin values; however, no significant differences were observed in serum ferritin of the newborn infants, whether their mothers had received iron supplements or not. These results have led us to reconsider the value of ferritin levels at birth as an index of iron stores in the infant. Iron supplements had no effect on the folate status in mothers or infants or on the frequency of obstetrical complications. A significant relationship was found between maternal folate levels and length of gestation. Folate supplementation may reduce the incidence of premature delivery.