The study, which was being co-ordinated at Leeds University, was halted after it emerged that two babies had suffered breathing and heart complications. An independent panel of experts has been appointed by the NHS Executive, the Medical Research Council and the university, to investigate the error.
Doctors were trying out a new treatment for birth asphyxia, a condition in which the brain is starved of oxygen. The condition is the commonest cause of avoidable death and handicap arising in labour and birth.
A total of 53 babies at 25 hospitals in eight European countries were taking part in the trial. Half were given the drug magnesium sulphate, a well-established therapy, and half received a harmless salt solution as placebo. The progress of the groups was then compared.
Doctors discovered that all the babies receiving magnesium sulphate had been given double the correct dosage of the drug after two babies in Sweden and Finland suffered breathing and heart problems, and the trial was stopped.
Fourteen babies have died since the study began in December last year, but the figure is statistically normal for the condition, and is not believed to be related to the drug overdose.
Rachel Chapman, spokeswoman for the trial, said yesterday: "The error happened when the magnesium sulphate was ordered and was the result of confusion over different ways of describing the formulation."
Of the babies taking part, 39 were at 15 hospitals in Britain, including Leeds General Infirmary and St James's Hospital, Leeds.
The decision to suspend the trial on 25 September was taken by Professor Malcolm Levine, professor of paediatrics and child health care at Leeds University, and clinical director of the trial. Ms Chapman said magnesium sulphate was a safe substance which had been given to pregnant women for 60 years to suppress labour, and was also used to treat high blood pressure.
The aim of the trial was to see whether topping up natural magnesium levels in the body could protect the brain from the effects of birth asphyxia.
Letters had been sent out to the parents who had volunteered their babies for the trial explaining the situation. They were being invited to see a local consultant if they wished.Reuse content