- Fetal seizures are an unusual phenomenon. When diagnosed by ultrasonography, they are frequently associated with malformations and carry a poor prognosis. We describe first trimester seizures in two siblings with arthrogryposis multiplex congenita. In both cases, convulsions appeared before other sonographic signs of the disease. Review of the literature revealed 11 other cases of fetal seizures diagnosed by ultrasound, all later in gestation. Fetal seizures may be the first manifestation of defective neural and motor development. Therefore, in pregnancies at high risk for neuromuscular disease, early sonographic evaluation of fetal motility, in addition to the anatomical survey, is advised. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.