Abstract
This retrospective study involved 470 pregnant women who first attended the antenatal clinic of
Sanpatong Hospital in Chiang Mai Province in the period from October 2005 to March 2007. The objective
was to determine the prevalence and causes of anemia in pregnant women and to study the association
between thalassemia traits and anemic status. All pregnant subjects received screening for hemoglobin concentration, hematocrit level, mean corpuscular volume (MCV), one-tube osmotic fragility test (OF
test), and serology for hepatitis B virus, syphilis and anti-HIV. In anemia cases, a therapeutic trial with
iron supplementation was performed in order to assess iron status. In cases positive for thalassemia
screening tests were taken of hemoglobin electrophoresis, hemoglobin A2 level and PCR for alpha thalassemia-
1 trait. Thalassemia traits and hemoglobinopathies were detected in 97 cases (20.7%). The prevalence
of anemia was 23.2 percent (109/470). Classified by trimester, the prevalence was 19.3, 24.5 and 43.2
percent in the first, second and third trimesters, respectively. In anemic pregnant women, the proportion
of thalassemia traits was 46.3 percent (50/108) and the proportion of iron deficiency anemia was 40.6
percent (28/69). Among the thalassemia traits group, the proportion of anemic status was 51.5 percent,
and anemic status in β-thalassemia trait was 70 percent; in α-thalassemia-1 trait, 68.7 percent; in α-thalassemia-
1 and HbE trait, in 40 percent; and HbE trait 28.2 percent. The overall thalassemia trait was significantly
associated with anemic status (OR 5.7,95%CI 3.5-9.3 ), p<0.00, and the α-thalassemia-1 trait and the
β-thalassemia trait were also statistically and significantly associated with anemic status. In conclusion,
the prevalence of anemia in pregnant women attending Sanpatong Hospital was 23.2 percent. The main
causes of anemia were thalassemia traits and iron deficiency anemia. The prevalence of thalassemia traits
in pregnant women in the present study was high and the subjects with thalassemia traits, α-thalassemia-
1 trait and β-thalassemia trait were associated with anemic status.
