Is fetal cardiac function gender dependent?

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. To investigate gender-related differences in fetal cardiac function. 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. 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. 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