Congenital myotonic dystrophy is an autosomal dominant condition with estimated incidence of 13/100000(1). We describe here a case of congenital myotonic dystrophy suspected antenatally due to maternal poly- hydramnios on antenatal ultrasound scan. A twenty-seven-year-old primigravida

INDIAN PEDIATRICS 746 VOLUME 41__JULY 17, 2004 dystrophy as a significant cause of idiopathic polyhydramnios. They suggested that all women having polyhydramnios with either a family history of myotonic dystrophy or ultrasonographic evidence of fetal hypotonia, including positional abnormalities of extremities should be offered DNA testing. It appears that prenatal ventriculomegaly may also be an important ultrasonographic finding suggesting congenital myotonic dystrophy. If idiopathic hydramnios is identified in a mother and dysfunctional fetal swallowing is seen, three fetal neuromuscular disorders should be ruled out –X-linked myotubular myopathy, congenital myotonic dystrophy and congenital nemaline myopathy(3) .