Objective To evaluate the outcome of pregnancies with proven and well-dated primary cytomegalovirus (CMV) infection with and without abnormal fetal ultrasound and magnetic resonance imaging (MRI) findings. Methods This was a prospective study of 38 singleton pregnancies with proven vertical transmission of CMV and prenatal ultrasound and MRI examinations. Entry requirements included precise dating of the pregnancy and known time of maternal infection. Neonatal follow-up was a strict requirement, all neonates having eye fundus examination, a brain ultrasound scan and a hearing evaluation. All children were followed up by specialists in child development. Results Primary CMV infection occurred during the first trimester in 10 patients, the second trimester in 19 and the third trimester in nine. Twenty-four of 29 patients with first- or second-trimester infections delivered; the other five underwent termination of pregnancy (TOP). Three patients had abnormal sonographic findings with normal MRI. Of these, two had damage to the auditory system. In both cases, infection occurred during the first trimester. In 16 patients with first- or second-trimester infection, both ultrasound and MRI exams were normal; there was one TOP but all other cases had favorable outcome, with normal hearing and developmental evaluations. The outcome of five pregnancies with subtle MRI findings and normal ultrasound exam was also favorable. None of the children infected during the third trimester was affected. Conclusion The outcome of congenital primary CMV infection with normal prenatal ultrasound and MRI exams is favorable. The prognostic value of subtle MRI findings is limited and when such findings are isolated, termination of pregnancy is unlikely to be justified.