RESUMEN
Objective To construct reference ranges of cardiac size and morphologic parameters in low-risk fetuses at 28-39 gestational weeks using two-dimensional speckle tracking technique.Methods A prospective collection of 453 low-risk singleton pregnancies with echocardiography at Obstetrics and Gynecology Hospital,Fudan University was used to assess the size(length,width,and area)and morphology(sphericity index,i.e.,the ratio of length to width)of the fetal four-chamber view and two ventricles using two-dimensional speckle tracking technique.Repeated inter-and intra-observer agreement of measurements was assessed using the intraclass correlation coefficients(ICCs).Statistical analysis of cardiac measurement parameters was performed to establish reference ranges of values for cardiac size and morphology in low-risk fetuses.Results The inter-and intra-group ICCs for reproducibility tests of fetal cardiac parameters measurements were 0.691 to 0.980.Fetal four-chamber view and ventricular size increased with gestational week(all P<0.001),the end-diastolic length of the left ventricle was larger than that of the right ventricle,and the end-diastolic diameter was smaller than that of the right ventricle(both P<0.001),while there was no significant difference in the end-diastolic area of the two ventricles(P= 0.050).The spherical index of four-chamber view did not correlate with gestational week(P=0.811).The sphericity index of the basal and intermediate segments of the left ventricle was greater than that of the right ventricle,and the sphericity index of the apical segment was less than that of the right ventricle,the differences were statistically significant(all P<0.01).Conclusion The two-dimensional speckle tracking technique for measuring fetal cardiac parameters has good reproducibility.The reference ranges for cardiac size and morphology in low-risk fetuses developed in this study will be useful for prenatal evaluation of cardiac remodeling.