Premature or low-birthweight babies are up to three times as likely to be hyperactive as babies born at full term, according to research published today in the British Medical Journal's Archives of Disease in Childhood.

Even babies born at 34-36 weeks are 70% more likely to develop hyperkinetic disorder (HKD) - characterised by hyperactivity, a low attention span and impulsive behaviour - than those born at 37 or more weeks.

The risk for those born before 34 weeks is almost threefold. HKD affects up to one in 50 children. The UK has the highest premature baby rate in Europe.