The ventouse cap, developed in Sweden 40 years ago, works by suction and is supposed to help ease a baby from the womb after being placed over its head.
It has been increasingly used in Britain in the past 10 years; NHS doctors had previously been more likely to use forceps if they needed to intervene. Although forceps remain the more popular instrument, some hospitals advocate the ventouse cap as a safer alternative and less likely to cause rupturing or scarring of the mother.
Medical accident campaigners say, however, that in the past few years, as use of the cap has increased, they have had regular complaints from parents about their babies having been maimed or brain-damaged during delivery. On several occasions the brain injuries have been so severe that the child has died.
"It appears that the problem is not so much with the cap's design as with its use," said Keith Miles of the campaigning organisation Action for Victims of Medical Accidents. "We are concerned that it is being used by people who are not sure of the procedure, and although it is recognised as safer than forceps, it can cause problems if it is put over the face, for instance."
Among recent cases, one baby delivered using a ventouse cap died after eight hours, and a coroner blamed the method. Medway NHS Trust admitted liability for the death of Kyle Rodway who suffered head injuries during birth.
In another case, in west London, a premature baby also died just hours after birth, and during the inquest the use of the ventouse cap was blamed for causing a brain haemorrhage.
Earlier this month, the parents of Joshua Quigley won legal aid to sue Royal Gloucestershire Health Trust after they claimed that he had been made permanently bald because of his difficult birth.
They say that the ventouse cap ripped an extensive layer of skin containing hair follicles from his scalp, and that he can only grow tufts of hair.
Sarah Goodman, the Quigleys' solicitor, said they believed the intense suction had caused the terrible head injuries.
"I understand that the ventouse cap was used in preference to forceps because forceps are believed to be more risky, but they could not get the cap on so they increased the pressure. The hospital does not appear to disagree with the Quigleys that the cap was a problem, but they dispute negligence."
Ms Goodman said she had also dealt with another case where a child's scalp was similarly permanently marked by the use of the cap.
"In that case there was not only a bald patch but the skin was also puckered and marked. The hospital denied liability but paid out compensation."
Doctors are awaiting publication of a review of research into the use of forceps and the ventouse cap, which is expected to show unequivocally that the suction device is far less harmful to a mother than forceps.
However, Dr Richard Johanson, a senior lecturer and consultant in obstetrics at North Staffordshire NHS Trust, who has conducted the review, said there was a need to carry out further research into the impact on babies of use of the ventouse cap.
He said: "From the point of view of the baby, we have not done any detailed work looking at major injuries, and the question remains which method causes less serious injury. You do find examples of babies killed or maimed in the literature.
"An instrument can be badly used. There is huge room for improvement - for getting people trained.
"But we should remember we have made substantial progress in childbirth. Fifty years ago there were instances where a doctor had to put a rope round a child to get it out."
Dr Johanson believes that damage is most likely to be done when the cap is used as part of a series of interventions, and he also warns that it should not be used on small, particularly premature, babies. "Using any of these methods should be a last resort," he said.
One mother who says she would never allow another child to be delivered using the ventouse cap is Kristin Green, whose first child suffered a brain haemorrhage after an assisted delivery.
She said: "I didn't know what was going on, but my husband saw this thing being used which was the ventouse and said: `That looks awful. Won't the pressure hurt his head?'"
Mr and Mrs Green took their son, Adam, home, only to have him rushed to casualty four weeks later after he became unconscious when fluid had built up inside his head and caused swelling.
The condition of Adam, who also suffered fits at the hospital, so concerned doctors at Chesterfield Hospital that they called the police and social services. The Greens, who were interviewed by detectives, were suspected of having shaken their son violently.
Mrs Green said: "It was so distressing. They let us go eventually but we had to be chaperoned by my mother for three months and not be left alone with the baby.
"All along our GP said she was convinced that it was the ventouse cap which had led to the problems and when we went back to the hospital a doctor checking Adam also told us it was the cap. I am never going to have that used again. I would rather have a Caesarean."Reuse content