Obstetric ultrasound and childhood malignancies.

The mothers of 1731 children who died of cancer in the United Kingdom between 1972 and 1981, together with the mothers of 1731 matched controls, were asked about exposure to diagnostic ultrasound during the relevant pregnancy. The claims of 103 case mothers and 103 control mothers were verified by hospital records. Exposure to ultrasound in utero did not differ between cancer and control children. It is concluded that ultrasound is safe as regards the risk of cancer and leukaemia. The observed difference between cases and controls exposed during the earlier years of ultrasound use may be due to the selective application of this technique to abnormal pregnancies at that time.