Supplementary Material for: Fetal strain and strain rate measured with speckle tracking echocardiography in maternal diabetes: systematic review

Introduction: The aim of this systematic review and meta-analysis was to evaluate fetal cardiac function in fetuses of mothers with diabetes compared to those of mothers without diabetes using 2D-STE.
Methods: Embase, MEDLINE and CENTRAL were searched for observational studies on 2D-STE fetal left and right ventricular global longitudinal strain and strain rate that included singleton, non-anomalous pregnancies complicated by pregestational or gestational diabetes mellitus compared to uncomplicated pregnancies. The strain values were pooled per 4 weeks of gestation for meta-analysis using random-effects models.
Results: Fifteen studies met the criteria, including 990 fetuses of diabetic mothers and 1,645 control fetuses. The study design was cross-sectional in fourteen studies and longitudinal in one study. Gestational age, type of diabetes, ultrasound device and 2D-STE software varied between the studies. Glycemic control and type of treatment were often lacking. In fetuses of diabetic mothers versus healthy mothers, left ventricular strain was significantly decreased (7 studies), increased (1 study) or not significantly different (7 studies). Right ventricular strain was decreased (7 studies), increased (1 study) or not different (2 studies). Left ventricular strain rate was decreased (3 studies), increased (1 study) or not different (2 studies). Right ventricular strain rate was increased (1 study) or not different (2 studies).
Conclusion: Fetuses of mothers with diabetes show evidence of systolic dysfunction, which is more visible in the right ventricle. Contradictory results are probably due to suboptimal study designs and variation in gestational age, diabetes severity, image acquisition and software. Large prospective longitudinal studies are needed to assess fetal myocardial function with 2D-STE in pregestational diabetes mellitus type 1 and 2 and gestational diabetes mellitus pregnancies. The influence of glycemic control, BMI and treatment should be evaluated.