Abstract Most fetuses in developed countries are exposed in utero to diagnostic ultrasound examination.
Many pregnant women express concern about whether the procedure harms the fetus.
Since most routine ultrasound examinations are done at weeks 16-22, when the fetal brain is developing rapidly, effects on neuronal migration are possible. We have sought an association between routine ultrasonography in utero and reading and writing skills among children in primary school. At the age of 8 or 9 years, children of women who had taken part in two randomised, controlled trials of routine ultrasonography during pregnancy were followed-up. The women had attended the clinics of 60 general practitioners in central Norway during 1979-81. A subgroup of 603 children underwent specific tests for dyslexia.