Prevalence of Hypertrophic Cardiomyopathy in Fetuses of Mothers with Gestational Diabetes before Initiating Treatment.

 To evaluate the prevalence of hypertrophic cardiomyopathy (HCM) in fetuses of pregnant women with gestational diabetes mellitus (GDM) in the beginning of the treatment.  A cross-sectional study was performed between July 1, 2013, and December 20, 2013, in a public maternity clinic in southern Brazil. The subjects were 63 fetuses of mothers with gestational diabetes, with a single pregnancy and no other associated pathologies. We diagnosed HCM through a fetal echocardiography before treatment and evaluated the maternal and fetal characteristics.  The average age of the pregnant women was 32.32 (±6.2) years, and the average gestational age at the time of the evaluation was 30.59 (±2.27) weeks. The interventricular septum thickness showed a standard deviation of more than two in 50.8% of the fetuses (95% confidence interval [95%CI]: 38.1-63.5%). The left ventricular wall thickness showed a standard deviation of more than 2 in 13 (20.6%) fetuses (95%CI: 11.1-30.2%). The HCM was confirmed in 54% of the fetuses (95%CI: 41.3-65.1%). The fetal abdominal circumference was normal in 46 (73%) fetuses, and 50% of these fetuses had HCM.  The prevalence of hypertrophic cardiomyopathy in fetuses of pregnant women with GDM before treatment was of 54% (95%CI: 41.3-65.1%).