To preliminarily investigate the predictive value of fetal cardiac parameters for fetal growth restriction (FGR).

A total of 50 pregnant women who underwent fetal echocardiography during the late gestational period and were clinically suspected of having FGR (observation group) at the Second Affiliated Hospital of Wenzhou Medical University from January 2018 to April 2022 were enrolled in the study, and 56 normal pregnant women who underwent fetal heart examination during the same time period were selected as controls. Pregnant women with suspected FGR were divided into two subgroups based on postnatal neonatal body weight: FGR-confirmed group and FGR-improved group. Fetal growth and umbilical artery, middle cerebral artery, and aortic isthmus blood flow were recorded. Fetal cardiac parameters were obtained, including right atrial transverse diameter, left atrial transverse diameter, left ventriclular transverse diameter, right ventriclular transverse diameter, pulmonary artery diameter, aorta diameter, aorta isthmus diameter, ductus arteriosus arch diameter, right atrial transverse diameter/left atrial transverse diameter ratio, right ventricular transverse diameter/left ventricular transverse diameter ratio, left ventricular spherical index, right ventricular spherical index, left ventricular spherical index/right ventricular spherical index ratio, aortic diameter/pulmonary artery diameter ratio, and aorta isthmus diameter/ductus arteriosus arch diameter ratio. The basic information of the pregnant women as well as the information on the delivery and outcome of the pregnancy was also recorded. Analysis of variance or the Kruskal-Wallis rank test was used to compare the above parameters among the FGR-confirmed group, FGR-improved group, and control group. Further pairwise comparisons between groups were performed by the LSD-t test or Bonferroni method. Spearman correlation analysis was used to assess the correlation between each parameter and FGR-confirmed group and FGR-improved group. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the efficacy of each parameter in diagnosing FGR.

The FGR-confirmed group had significantly higher right atrial transverse diameter/left atrial transverse diameter ratio [1.27 (1.10, 1.44) vs 1.09 (1.00, 1.20), Z=2.581, P=0.030], and significantly lower values of aortic isthmus diameter, aortic isthmus diameter/arterial ductal arch diameter ratio, and left ventricular spherical index/right ventricular spherical index ratio [2.80 (2.50, 3.25) mm vs 3.50 (3.03, 3.78) mm, Z=-3.673, P=0.001; 0.73±0.18 vs 0.96±0.19, t=-5.043, P<0.001; 0.72±0.11 vs 0.80±0.11, t=-2.255, P=0.026] than the FGR-improved group. Compared with the control group, the aortic isthmus diameter [2.80 (2.50, 3.25) mm vs 3.30 (3.00, 3.80) mm, Z=-3.991, P<0.001], aortic isthmus diameter/arterial ductal arch diameter ratio (0.73±0.18 vs 1.00±0.12, t=-7.143, P<0.001), left ventricular spherical index/right ventricular spherical index ratio (0.72±0.11 vs 0.83±0.14, t=-3.904, P<0.001), and left atrial transverse diameter [11.0 (10.0, 12.0) mm vs 12.0 (11.0. 13.0) mm, Z=-2.624, P=0.026] were significantly lower, while the right atrial transverse diameter/left atrial transverse diameter ratio [1.27 (1.10 , 1.44) vs 1.00 (1.00, 1.10), Z=4.959, P<0.001], right atrial transverse diameter [14.0 (12.5, 16.0) mm vs 12.0 (11.0, 14.0) mm, Z=2.599, P=0.028], right ventricular transverse diameter/left ventricular transverse diameter ratio [1.12 (1.04, 1.32) vs 1.00 (0.93, 1.10), Z=3.591, P=0.001], right ventricular sphericity index [0.62 (0.58, 0.71) vs 0.58 (0.52, 0.65), Z=2.530, P=0.034], and arterial ductal arch diameter [3.90 (3.45, 4.70) mm vs 3.35 (3.08, 3.75) mm, Z=3.722, P=0.001] were signficantly higher in the FGR-confirmed group. In contrast, these parameters were not statistically different between the FGR-improved group and the control group (P>0.05 for all). Correlation analyses showed that body mass index, reverse blood flow in the diastolic phase of the aortic isthmus, abnormal umbilical cord blood flow and/or middle cerebral artery blood flow, premature delivery, emergency cesarean section, and placenta or umbilical cord abnormalities were related to FGR outcome (r=0.306, P=0.036; r=0.587, P<0.001; r=0.450, P=0.001; r=0.542, P<0.001; r=0.421, P=0.002; r=0.365, P=0.010). Gestational diabetes, gestational hypertension, oligohydramnios, and whether FGR was suspected before 32 weeks were not statistically correlated with FGR outcome (P>0.05 for all). In the observation group, the sensitivity of the aortic isthmus diameter/ductus arteriosus arch diameter ratio and aortic isthmus diameter for the diagnosis of FGR was 75% and 83%, the specificity was 72% and 68%, and the area under the ROC curve was 0.81 and 0.77, respectively.

The enlargement of the fetal right heart and the reduction of the diameter of the aortic isthmus are closely related to FGR, which can assist in the diagnosis of FGR. The ratio of the diameter of the aortic isthmus to the diameter of the aortic arch has high diagnostic performance for FGR. Fetal cardiac examination is an effective tool for clinical prediction of FGR.