The parents of the UK's youngest surviving heart transplant patient yesterday spoke for the first time about their daughter's life-saving operation.

The parents of the UK's youngest surviving heart transplant patient yesterday spoke for the first time about their daughter's life-saving operation.

Sarah Cox was just 23 days old and on the brink of death when a donor heart was found from abroad.

Now a healthy two-year-old, Sarah is the youngest child to have had a heart transplant in the UK who has survived.

Her parents, Jennie and Nigel Cox, yesterday broke their silence to urge others to join the NHS organ donor register.

They also called for more debate on the UK's rules which prevent donor organs from being taken from children under two months.

The practice is allowed in the US, Canada and many other European countries.

Sarah was born healthy but her heart was damaged when she contracted viral meningitis aged just six days.

Just 15 days later, she was so ill that her parents were told to say goodbye as she was expected to survive for only another 24 to 48 hours.

"We were completely devastated. We couldn't believe what we were being told," said Mrs Cox.

But out of the blue came the call which offered a donor heart to surgeons at Great Ormond Street Hospital in London.

The operation was a success and baby Sarah was soon out of intensive care.

Now the couple say Sarah is like any other lively two-year-old, except her daily routine includes medicine in the morning and at night.

"She's just a normal little girl," said Mrs Cox.

The couple have never spoken publicly about Sarah's transplant but yesterday appealed for more people to join the donor register.

Although 90% of people told a UK transplant survey they are in favour of organ donation in principle, only 26% have joined the register.

Current UK guidelines prohibit donor organs from being taken from children aged under two months but the heart which saved Sarah's life was donated from a child elsewhere in Europe, where the rules are different.

Mrs Cox said: "We are immensely grateful to the family that made that decision to donate Sarah's organ and we are extremely relieved that the rules in that other country weren't the same as they are here."

Since April 2008, 108 people have received heart transplants, including 28 children aged under 18.

Almost 8000 people are currently waiting for an organ transplant, including 158 under-18s.