Is fetal cardiac function gender dependent?

Introduction: An increased nuchal translucency (NT) is more common in males. A delayed diastolic cardiac function maturation has been proposed to explain this and the reported gender-related differences in ductus venosus (DV) flow. Objective: To investigate gender-related differences in fetal cardiac function. Methods: One hundred and ninety karyotypically/phenotypically normal fetuses with structurally normal hearts and known NT measurement, (104 > 95th percentile), were prospectively included between 1 October 2003 and 1 April 2009. They had been referred for fetal echocardiography. Three hundred and nine echocardiograms were performed between 11 and 35 weeks' gestation. The atrioventricular valve E- and A-wave peak velocity, E/A-velocity ratio and E/TVI ratio, myocardial performance index, semilunar valves acceleration time (AT) and peak velocity, stroke volume and cardiac output as well as DV pulsatility index for veins at 11-14 weeks' gestation, were measured. A multilevel analysis was performed using the NT (multiples of the median) as a continuous variable. Results: The male female ratio was 1.56:1. The tricuspid valve E/TVI was significantly higher and pulmonary valve AT significantly lower in females compared to males. No other significant differences in cardiac function were found. Conclusions: Our findings suggest better right ventricular (RV) relaxation and increased RV afterload in female fetuses, independent of NT thickness, between 11 and 35 weeks' gestation.