Hemoglobin levels in normal-weight and obese patients during pregnancy. 
To determine if there is a difference in hemoglobin levels in normal-weight patients compared with obese women during the second trimester of pregnancy.  This was a retrospective cohort study of hemoglobin levels in the second trimester of pregnancy from 2009 to 2010 in 46 primarily indigent patients (23 normal weight and 23 obese) using the current body mass index classification.  There were no differences in demographic and baseline characteristics between the two study groups except for body mass index as expected (p < 0.001).  Mean second trimester hemoglobin levels in the obese group (10.8 g/dL) were 6.1% (0.7 g/dL) lower compared with normal-weight patients (mean 11.5 g/dL, p = 0.018).  Second trimester hemoglobin levels are lower in obese patients when compared to their normal weight counterparts.  These lower levels in obese patients may be clinically significant.