Ultrasound scanning of pregnant women may cause their children to have delayed speech development, according to a Canadian study.
Professor James Campbell, an ear, nose and throat surgeon in Alberta, Canada, compared a group of 72 children who had speech problems with a similar group with no such difficulties.He found that most of those with delayed speech had been exposed to ultrasound in the womb, whereas most of those with normal speech had not. "The possibility of subtle microscopic changes in developing neural tissue exposed to ultrasound waves has to be considered," he concluded,
Following the study, the UK group AIMS Association for Improvements in the Maternity Services has written to the UK's Chief Medical Officer, Dr Kenneth Calman, calling for an inquiry into whether the number of children with delayed speech is on the increase, given that pregnant women in Britain are routinely subjected to scanning with ultrasound. AIMS also wants the study to be replicated in the UK.
Beverley Beech, honorary chair of AIMS, says the Canadian findings are particularly alarming because the women in the study had only one scan. In Britain, supposedly normal pregnancies usually involve at least two such examinations many more if there are thought to be problems. If just one scan can cause delayed speech, she is particularly concerned about the cumulative effect of multiple examinations.
Professor Campbell's findings are the latest in a series to suggest that ultrasound scanning may be harmful, and in any case makes no difference to pregnancy outcome. Earlier, researchers in New York concluded that scans provided no benefits after studying 15,000 women (WDDTY, vol 4 no 8); Norwegian researchers concluded that ultrasound may cause mild brain damage (WDDTY, vol 4 no 5). Other studies have indicated that children who were scanned in the womb have an increased incidence of dyslexia, and low birth weight, says Beech.