Perinatal Anemia By Andrew W Walter, MS, MD, Sidney Kimmel Medical College at Thomas Jefferson University Reviewed / Revised Dec 2022 View Patient Education Etiology Symptoms and Signs Evaluation Treatment Key Points Topic Resources Age-Specific Values for Hemoglobi... Transfusion Thresholds for... Anemia is a reduction in red cell mass or hemoglobin and is usually defined as hemoglobin or hematocrit > 2 standard deviations below the mean for age.