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 ... 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. 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. And when the children also later used the phones they were, overall, 80 per cent more likely to suffer from difficulties with behaviour. They were 25 per cent more at risk from emotional problems, 34 per cent more likely to suffer from difficulties relating to their peers, 35 per cent more likely to be hyperactive, and 49 per cent more prone to problems with conduct.