Women who use mobile phones when pregnant are more likely to give birth to children with behavioural problems, according to authoritative research.
A giant study, which surveyed more than 13,000 children, found that using the handsets just two or three times a day was enough to raise the risk of their babies developing hyperactivity and difficulties with conduct, emotions and relationships by the time they reached school age. And it adds that the likelihood is even greater if the children themselves used the phones before the age of seven.
The results of the study, the first of its kind, have taken the top scientists who conducted it by surprise. But they follow warnings against both pregnant women and children using mobiles by the official Russian radiation watchdog body, which believes that the peril they pose "is not much lower than the risk to children's health from tobacco or alcohol".
The research - at the universities of California, Los Angeles (UCLA) and Aarhus, Denmark - is to be published in the July issue of the journal Epidemiology and will carry particular weight because one of its authors has been sceptical that mobile phones pose a risk to health.
UCLA's Professor Leeka Kheifets - who serves on a key committee of the International Commission on Non-Ionizing Radiation Protection, the body that sets the guidelines for exposure to mobile phones - wrote three and a half years ago that the results of studies on people who used them "to date give no consistent evidence of a causal relationship between exposure to radiofrequency fields and any adverse health effect".
The scientists questioned the mothers of 13,159 children born in Denmark in the late 1990s about their use of the phones in pregnancy, and their children's use of them and behaviour up to the age of seven. As they gave birth before mobiles became universal, about half of the mothers had used them infrequently or not at all, enabling comparisons to be made.
They found that mothers who did use the handsets were 54 per cent more likely to have children with behavioural problems and that the likelihood increased with the amount of potential exposure to the radiation...