ORIGINAL CONTRIBUTION Maternal Hemoglobin Concentration During Pregnancy and Risk of Stillbirth

THE RELATIONSHIP BETWEEN MA-ternal hematological param-eters and pregnancy outcomehas been a source of continu-ing controversy. In developed coun-tries, not only maternal anemia1-3 but also high hemoglobin concentration during pregnancy4-9 has been reported to increase the risks of unfavorable out-comes such as small-for-gestational-age (SGA) birth, preterm birth, and perinatal death. The associations be-tween hemoglobin concentration in early pregnancy, changes in hemoglo-bin concentration during pregnancy, and risk of stillbirth are not known.10 In this large population-based case-control study, we investigated the as-sociations between the hemoglobin concentration at the first measure-ment during antenatal care, weekly change in hemoglobin concentration during early and late pregnancy, and risk of stillbirth. Because the causes of stillbirth are varied, we also investi-gated hemoglobin-related risks in dif-ferent subgroups of stillbirths