The association between maternal anemia and pregnancy outcomes has been investigated in many epidemiological studies, but the findings remain inconsistent. In our previous study based on the Kola Birth Registry (KBR), we observed that maternal anemia defined as hemoglobin concentration below 120 g/l was negatively associated with the risk of stillbirth and preterm birth and positively associated with foetal growth (1). However, our anemic group was heterogeneous and included women with hemoglobin between 110 and 120 g/l, which cannot be classified as anemic according to the WHO. This study aims to achieve a more detailed analysis of different maternal hemoglobin concentrations and their associations with stillbirth, preterm birth and foetal growth in using the data from the KBR.