The warning came after the Diana Princess of Wales Children's Hospital in Birmingham offered to return the hearts of 1,500 dead babies to concerned parents. It has made the offer because it believes that many who signed post-mortem consent forms for "tissue research" in the past 30 years may not have realised the baby's hearts had been kept.
Professor Robert Anderson, president-elect of the British Paediatric Cardiac Association, said medical research in Britain "would never recover" from the setback if all the children's hearts kept in storage at hospitals were returned to parents for burial or cremation.
"It would not be a good thing to return all the hearts. When we removed the hearts it was our impression that the parents did know. So it came as quite a blow and certainly a surprise when it emerged that a lot of the parents didn't know," said Professor Anderson, who amassed a collection of children's hearts at the Royal Brompton Hospital in London and is now responsible for those stored at Great Ormond Street.
"If you explain what you are doing and why you need to do it, I would have thought the majority of parents would be happy for doctors to keep the hearts. They are doing far more good where they are than they would do by returning them and burying them." However Professor Anderson said he recognised there may be individual circumstances where parents wanted to have the hearts back and they should have the right to reclaim them.
Large collections of damaged and malformed hearts are stored at main hospitals throughout Britain. The hospitals are estimated to have retained the hearts of at least 11,000 children who died of cardiac disease in the past 40 years. The Royal Brompton and Great Ormond Street hospitals each have 2,000 stored. There are 1,500 in Birmingham, 1,000 in Leeds, and about 500 in Sunderland, Newcastle, Manchester and Bristol.
Officials at the Diana Princess of Wales Children's Hospital said a review of the post-mortem consent forms was now under way. A spokesman said: "If we get any inquiries from parents, we will work with them sensibly and constructively and meet their wishes whatever they may be."
The practice of tissue retention came to light after an investigation into high death rates in paediatric cardiac surgery at the Bristol Royal Infirmary. The infirmary has already introduced new consent forms explaining why doctors might wish to retain organs and some parents have decided to leave their children's hearts for continuing medical research.
Helen Rickard, 32, from Bristol, uncovered the practice when she discovered that her 11-month-old daughter, Samantha, had been buried without her heart. She has since reclaimed the heart, which is being stored at Great Ormond Street while she arranges the burial.
"All parents should have the right to reclaim their children's hearts," she said. "It is incredibly important to me. I want Samantha's heart put back in her coffin so it can decompose with the rest of her body. Although many parents would agree to have their child's heart taken out for medical research, it is a very personal thing and I would have said no."