en عمومى General گزارش مورد case report Gestational diabetes mellitus (GDM) is a teratogenic condition for the fetus. Congenital malformations among the newborns of diabetic mothers is 5-times greater than general population. Tetralogy of fallot is a common form of congenital heart defect. We would like to report a diagnosed case of fetal tetralogy of fallot based on findings including a ventricular septal defect (VSD), aortic valve overriding, bidirectional shunt via VSD in aortic long axis view, in addition to anomalies on the three-vessel view with small pulmonic annulus in a high risk mother with GDM with a gestational age of 19 weeks. It appears that although the risk of fetal cardiac malformations may be highest in women with GDM, all pregnancies of pre-gestational diabetes and GDM are at increased risk, given this, regular fetal echocardiographies should be consider in women with GDM. Tetralogy of Fallot, prenatal diagnosis, fetal echocardiography, gestational diabetes mellitus 59 63 http://intjmi.com/browse.php?a_code=A-10-1-220&slc_lang=en&sid=1 Alireza Golbabaei 10031947532846002015 10031947532846002015 No Department of Pediatrics cardiology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Ehsan Aghaei Moghaddam 10031947532846002016 10031947532846002016 No Department of Pediatrics cardiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran , Mohammad Taghi Majnoun 10031947532846002017 10031947532846002017 No Department of Pediatrics cardiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran Ali Mirabi 10031947532846002018 10031947532846002018 Yes Medical Student, Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.