WEDNESDAY, Feb. 4, 2026 (HealthDay News) -- In a high-income setting, maternal anemia and relative erythrocytosis are associated with severe neonatal morbidity and mortality (SNM-M), according to a study published online Feb. 3 in the Annals of Internal Medicine.
Ieta Shams, M.D., from the University of Toronto, and colleagues examined early pregnancy hemoglobin concentration and association with SNM-M in a high-income setting in a population-based, retrospective cohort study. Participants included women aged 18 to 50 years with a singleton birth between 2007 and 2023 and hemoglobin measurement at two to 12 weeks of gestation; 1,100,341 births were included in the study.
The researchers identified a U-shaped relation between early pregnancy hemoglobin concentration and SNM-M. The adjusted relative risk for SNM-M was 1.08 at a hemoglobin concentration of 105 g/L and 1.17 at 90 g/L compared with a hemoglobin value of 125 g/L and a corresponding SNM-M rate of 6.7 percent. The adjusted relative risk for SNM-M was 1.05 and 1.20 at hemoglobin concentrations of 135 and 150 g/L, respectively.
"In conclusion, these findings confirm the association between maternal anemia in pregnancy and unfavorable perinatal outcomes within a high-resource setting," the authors write. "Future prospective studies and clinical trials should evaluate neonatal outcomes across varying levels of hemoglobin correction and the optimal thresholds for initiating iron therapy."