RESUMEN
Objective To investigate the values of ultrasound measuring of the placenta thickness on evaluation of risks for alpha-thalassemia at the early pregnancy.Methods Two-dimensional ultrasound was performed to measure the thickness of placenta on 208 cases of fetuses with alpha-thalassemia and 52 cases of normal fetuses in control group.The placenta thickness was expressed as multiples of the median(MOM).Results At the early pregnancy,the group of fetuses with alpha-thalassemia had significantly higher placenta thickness compared to the fetuses without alpha-thalassemia(P＜0.001).However,there were no statistical significant difference in the placenta thickness between the other groups(P=0.100).Placenta thickness 1.18 MOM was the best critical point to predict alpha-thalassemia.The sensitivity and specificity of placenta thickness >1.18 MOM in prediction of alpha-thalassemia was 82.9%,84.7% respectively.Conclusions For those with high risks of alpha-thalassemia placenta thickness measuring is a safe,effective parameter for assessment because it could reduce unnecessary invasive procedures and improve the detecting rate of severe alpha-thalassemia.