In general, the diagnosis of pregnancy-related anemia relies on the estimation of the hemoglobin level. The findings of this study suggest that the additional estimation of serum ferritin – a reliable index of the iron stores – can improve the diagnosis of anemia. Hematological data of 150 pregnant women were retrospectively related to the courses of pregnancy, in particular to the incidence of premature labor contractions. 70% of the pregnant women included in the investigation had a serum ferritin value below 20 μg/l and thus iron deficiency. If the hemoglobin value alone had been estimated, 50.6 % of the women with iron deficiency (serum ferritin < 20 μg/l) would not have been detected among those pregnant women with a hemoglobin value of more than 11 g/dl. These findings are also of particular relevance as a significant correlation has been found between the incidence of premature labor contractions and the serum ferritin level: only 11 % of the pregnant women investigated whose serum ferritin values exceeded 20 μg/l had premature labor contractions, whereas premature labor was recorded in 48 % of the pregnant women with serum ferritin values below 10 μg/l.