Supplementary Material for: The Relationship between Cardiac Size and Shape Measurements and Cardiac Contractility in Intrauterine Growth Restricted Fetuses

Introduction: Fetal growth restriction (FGR) affects cardiac function and increases the risk of cardiac pathologies. We describe the relationship between cardiac contractility and cardiac size and shape in FGR and small-for-gestational age (SGA) fetuses to determine if ultrasound measurements can indicate functional cardiac sequelae. Methods: This prospective cohort study included fetuses with gestational ages of 23.0-39.0 weeks (FGR: n=55, SGA: n=40, appropriate for gestational age/AGA: n= 22). FGR was defined as fetuses with EFW <10th centile and abnormal arterial doppler studies; SGA was defined as fetuses with EFW <10th centile with normal doppler studies. Two-dimensional cardiac video clips of the 4-chamber view (4CV) were obtained for all fetuses and measurements of its size and shape were made. Speckle tracing measures of contractility were obtained as previously described. Individual size, shape, and speckle tracing measurements were compared by ANOVA between FGR, SGA, and appropriate for gestational age (AGA) groups. Comparisons by Mann Whitney U were used to compare a combined FGR+SGA group with the AGA group for all measurements. Abnormality was determined by simple count of values >95th centile or <5th centile based on predicted effect of FGR/SGA on each measurement. Frequency was binary, with a fetus assigned a 1 if they had any abnormal measurement, and 0 if not. Severity was determined by summing the abnormal measurements. Frequency and severity were determined independently for contractility versus size and shape and compared across groups using chi-squared and ANOVA respectively.