Abstract. The Hb level during pregnancy was followed in 113 non-anaemic women with uncomplicated pregnancy and birth weight of the baby above the 2.5th percentile. There was an inverse correlation close to statistical significance between the birth weight of the baby and the lowest Hb level reached during pregnancy as well as the Hb level in late pregnancy (38th week). A group of seven non-anaemic women with birth weight of the baby below the 2.5th percentile had a significantly higher (p<0.001) Hb level in late pregnancy than the normal group. Four of these cases had a statistically significant higher Hb level already in the second trimester. Trends in the reproductive history, complaints in the present pregnancy as well as results of hormone assays and the condition of the baby indicated that the seven cases represented a pathological group with fetal growth retardation. None of the women in the two groups were treated with diuretics. All had iron supplementation in high doses.