Racial disparities in maternal hemoglobin concentrations and pregnancy outcomes

To examine the association of maternal hemoglobin (Hb) concentrations with preterm and low birth weight (LBW) deliveries in African Americans compared to Caucasians.

We conducted a retrospective analysis of perinatal data on 17,338 African-American and Caucasian pregnant women who delivered at the George Washington University Hospital (GWUH) between January 1990 and December 2003. We used univariate and logistic regression analyses to examine for associations.

Compared to Caucasians (n=9432), African American mothers (n=7906) had a higher incidence of anemia (26.9% vs. 7.1%, P<0.001), preterm (22.1% vs. 12.8%, P<0.001) and LBW (18.6% vs. 9.7%, P<0.001) outcomes. This association increased with decreasing Hb concentrations in each race. Risk for preterm and LBW outcomes were higher in African Americans compared to Caucasians at Hb concentration ≥12 g/dL (P<0.007); however, there were no race-specific risk at Hb concentration <11 g/dL (P>0.05).

The association of race with preterm and LBW outcomes relates to maternal Hb. Our findings suggest: a) anemia is a strong risk factor that masks the influence of race, b) African American race could be a surrogate for other factors that contribute to adverse outcomes, and c) Caucasian race could be less adaptive to anemia.