Recessive congenital myotonia and pregnancy.

There is a group of genetic disorders of muscle associated with myotonia. Congenital myotonia, usually a benign disorder and myotonic dystrophy, potentially a serious disorder, belong to this group. Uterine recordings during labor in patients with congenital myotonia have not been previously reported. These records have been abnormal in patients with myotonic dystrophy which has been associated with serious obstetric complications. A case of congenital myotonia in pregnancy is reported. The record of uterine contractions was normal. Although the patient delivered a stillborn male, the etiology of the intrauterine fetal demise is obscure.