Supplementary Material for: Nomograms of Fetal Cardiac Dimensions at 18–41 Weeks of Gestation

<b><i>Objective:</i></b> There is a need for standardized reference values for cardiac dimensions in prenatal life. The objective of the present study was to construct nomograms for fetal cardiac dimensions using a well-defined echocardiographic methodology in a low-risk population. <b><i>Methods:</i></b> This is a prospective cohort study including 602 low-risk singleton pregnancies undergoing a standardized fetal echocardiography to accurately assess fetal cardiac, ventricular, and atrial dimensions. Parametric regressions were tested to model each measurement against gestational age from 18 to 41 weeks of gestation. <b><i>Results:</i></b> Nomograms were constructed for fetal cardiac dimensions (transverse and longitudinal diameters and areas) of the whole heart, atria, and ventricles, as well as myocardial wall thicknesses. All dimensions showed a progressive increase with gestational age. The best model for most parameters was a second-degree linear polynomial. Fetal cardiac, ventricular, and atrial diameters and areas were successfully obtained in 98.6% of the fetuses, while myocardial wall thicknesses could be obtained in 96.5% of the population. The results showed excellent interobserver and intraobserver reproducibility (intraclass correlation coefficient, ICC &gt; 0.811 and ICC &gt; 0.957, respectively). <b><i>Conclusions:</i></b> We provide standardized and comprehensively evaluated reference values for fetal cardiac morphometric parameters across gestation in a low-risk population. These no mograms would enable the early identification of different patterns of fetal cardiac remodeling.

<b><i>研究目标：</i></b> 产前心脏维度的标准化参考值仍存在迫切需求。本研究旨在基于明确定义的超声心动图检查方法，在低风险人群中构建胎儿心脏维度的列线图（nomogram）。<b><i>研究方法：</i></b> 本研究为前瞻性队列研究，纳入602例低风险单胎妊娠孕妇，对其实施标准化胎儿超声心动图（fetal echocardiography）检查，以精准评估胎儿心脏、心室及心房的维度指标。针对18至41孕周的胎龄，采用参数回归模型对各项测量指标与胎龄的关联进行拟合建模。<b><i>研究结果：</i></b> 本研究构建了胎儿整体心脏、心房及心室的心脏维度（包括横径、纵径及面积）以及心肌壁厚度的列线图。所有维度指标均随胎龄增加呈进行性升高趋势。多数参数的最优拟合模型为二阶线性多项式。98.6%的胎儿可成功获取心脏、心室及心房的直径与面积数据，96.5%的研究对象可获取心肌壁厚度数据。结果显示观察者间与观察者内重现性优异，组内相关系数（intraclass correlation coefficient, ICC）分别大于0.811与0.957。<b><i>研究结论：</i></b> 本研究为低风险人群提供了覆盖全孕周的胎儿心脏形态计量参数标准化参考值，并完成了全面评估。所构建的列线图可助力早期识别胎儿心脏重构的不同类型。