Diabetes is becoming more prevalent, affecting up to 9% of pregnant women in Australia. Women who have diabetes before pregnancy have an increased risk of structural heart defects and require careful review at the time of the 20 week anomaly scan. A preliminary assessment may be performed at 12 weeks gestation, at the time of NT assessment. More recently, an association between cardiac hypertrophy and maternal diabetes has been recognised - and has been reported to affect up to 30% of these infants.

Fetal myocardial hypertrophy is characterized by increased interventricular septal, left and right ventricular wall thickness at the end of diastole. As hypertrophy becomes more severe, ventricular stiffness increases, affecting diastolic ventricular filling as well as systolic cardiac function. These features can be assessed using 'M' mode and Doppler ultrasound.

In this study we aim to ascertain whether these indices of cardiac function can be readily measured in the third trimester of pregnancy during a routine growth and wellbeing scan and to determine whether changes seen in the fetal period correlate with neonatal cardiac performance.