Hemoglobin concentrations influence birth outcomes in pregnant african-american adolescents.

Chang SC, O'Brien KO, Nathanson MS, Mancini J, Witter FR
J Nutr 2003;133(7):2348-2355.
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This article provides additional insight into the relationship between hemoglobin and birth outcome. The influence of anemia or hemoconcentration on birth outcome has been discussed for years. This study nicely shows that low hemoglobin levels (< 9.5 g/dL) but also high levels (> 12 g/dL) have a negative impact. While low hemoglobin levels are associated with premature birth and growth retardation due to feto-placental dysfunction, high hemoglobin levels result in hemoconcentration which again reduces feto-placental blood flow. The message for clinicians is: (1) treat manifest anemia and coexisting factors such as STD and malnutrition quickly, and (2) keep the patient in an optimal hemoglobin range (probably between 10-11 g/dL).
The special relationship between preeclampsia and hemoglobin levels is under investigation. In this case the underlying factor is probably due to plasma volume changes rather than real red cell changes.

– Christian Breymann