Fetal heart size measurements as new predictors of homozygous α‐thalassemia‐1 in mid‐pregnancy

Objective To evaluate the efficacy of using fetal heart size measurements derived from axial echocardiography to predict homozygous α-thalassemia-1. Design Prospective diagnostic study. Setting The carrier rate of α-thalassemia-1 (–/αα) in China's Guangxi Zhuang Autonomous Region is approximately 15%. If both parents are carriers, the risk of homozygous α-thalassemia-1 in one pregnancy is 25%. Patients Singleton mid-pregnancies at risk of homozygous α-thalassemia-1 were enrolled. Outcome Measures Fetal heart measurements, including heart diameter (HD), heart length (HL), heart circumference (HC), and heart area (HA), were measured. The z-scores for these heart parameters were then calculated separately based on previously constructed z-score models. Finally, the accuracy of these predictive variables was analyzed and compared to that achieved by cardiothoracic ratio (CTR) using a receiver operating characteristic (ROC) curves analysis. Results A total of 214 singleton pregnancies were recruited. The discriminatory power of HA and HD z-scores was better (z-test P .05) that of CTR. HD combined with HA z-scores had the highest sensitivity (100%), and the specificity of HD and/or HA z-scores was 100%. Conclusion Fetal heart size measurements are novel, effective and noninvasive predictors of homozygosity for α-thalassemia-1 in mid-pregnancy. The discriminatory power of HD and HA z-scores was better than while that of HC and HL z-scores was comparable to that of CTR. Further investigation is needed to understand the effectiveness of these predictors.