Dr Andreas Tzakis, leader of the team that carried out the transplants at the Children's Hospital of Pittsburgh, Pennsylvania, told a press conference: 'Perhaps we inflicted unnecessary pain.' She had been conscious until very close to the end, he said. 'I think Laura came very close to making it.'
Doctors had known for about two weeks that Laura, aged five, was suffering from a serious side effect of drugs used to fight organ rejection.
In the early hours of yesterday morning Fran Davies and her husband, Les, realised that their daughter had given up her long battle for survival. They were at her bedside when doctors switched off her ventilator at 7.45am (2.45am US time). She had been heavily sedated for some days.
Laura, who had appeared to recover well from a 15-hour operation in September when she was given six new organs - the most ambitious multiple transplant attempted. But she developed breathing difficulties and cancer-like growths on many organs due to the anti-rejection drug FK506, which suppresses the immune system.
On Wednesday night, her condition deteriorated further. Adrian Bianchi, a consultant neonatal and paediatric surgeon at the Royal Manchester Children's Hospital who had cared for Laura from her birth, said last night: 'There came a time when it was obvious that there was nowhere else for her to go. The right management meant that she had a peaceful and dignified death. It would have been wrong to go on and on treating her.'
Laura's grandmother, Barbara Cooper, said last night: 'Fran decided Laura was not fighting any more and asked the doctors to switch off the ventilator. She had been preparing for the end and knew that the time had come.'
Laura - from Eccles, Greater Manchester - was born with a perished small bowel. A small bowel and liver transplant became her only hope of survival after she developed liver failure, and she underwent the operation in Pittsburgh in June 1992. Her treatment was paid for by public donations of almost pounds 600,000, including pounds 150,000 from King Fahd of Saudia Arabia.
She recovered well and returned home last November, but the powerful anti-rejection drugs caused problems and had to be stopped. Her small bowel stopped working and her body began to reject the donated organs. Other organs also began to fail. The family returned to the US in May and in September she received kidneys, stomach, small and large bowels, liver and pancreas, from a young child.
The second operation triggered a passionate moral debate in Britain, with some critics claiming that Laura was now a guinea pig for cash-hungry American doctors. Dr Richard Nicholson, a paediatrician and editor of the Bulletin of Medical Ethics, said last night that the second operation was a mistake, subjecting Laura to so much pain and discomfort for little gain. 'It was experimental and there was a small chance of success.'
Mr Bianchi, disagrees strongly. 'Whenever there was a sensible, possible chance, we took it . . . That which seemed hopeless and impossible today, will be routine for so many tomorrow.' The first European small bowel transplant in a child was carried out in April in Birmingham.