Comparison of red blood cell hematology among normal, alpha-thalassemia-1 trait, and hemoglobin Bart's fetuses at mid-pregnancy.

The objective of this study was to compare red blood cell indices among normal, alpha-thalassemia-1 trait, and hemoglobin (Hb) Bart's fetuses at mid-pregnancy. A total of 87 pregnancies (88 fetuses) at risk of homozygous alpha-thalassemia-1, who underwent cordocentesis including the measurement of Hb level and red blood cell indices of fetuses at 18-22 weeks of gestation at Maharaj Nakorn Chiang Mai Hospital, were recruited into this study. The final outcome was based on the fetal DNA analysis using PCR technique for SEA type alpha-thalassemia-1. Fetuses were divided into three groups: normal, alpha-thalassemia-1 trait, and homozygous alpha-thalassemia-1 (Hb Bart's disease). The mean gestational age of the 87 pregnant women recruited into the study was 18.7 +/- 0.8 weeks. According to the DNA analysis, the incidence of Hb Bart's disease, alpha-thalassemia-1 trait, and normal fetuses were 29.5%, 45.5%, and 25%, respectively. The mean Hb level, mean corpuscular volume, mean corpuscular Hb, and mean cell Hb concentration were significantly different in all three groups of fetuses. Moreover, these differences were also found among fetuses with the alpha-thalassemia-1 trait and those that were normal. Ninety-two percent of fetuses with Hb Bart's disease had some degree of anemia at mid-pregnancy. However, two Hb Bart's fetuses did not have anemia. Furthermore, two fetuses in the alpha-thalassemia-1 trait group were mildly anemic, but most (95%) were not. There is a highly significant difference in red blood cell indices among normal, alpha-thalassemia-1 trait, and Hb Bart's fetuses, and most fetuses with Hb Bart's disease have some degree of anemia from mid-pregnancy.