Kaven Simmons arrived at 23 weeks, weighing just over 1lb and doctors put his chances of survival at nil.
He was so fragile that his ribs broke with the effort of breathing, and both of his legs fractured as his nappy was changed.
As he hung on to life he suffered a flesh-eating bug inside his stomach, and he underwent a gruelling six operations and 50 blood transfusions.
But after six months in hospital, Kaven - one the most premature babies ever born in the UK - was finally allowed to go home.
His mom knew the moment he put his tiny hand on hers, he was going to be all right." "He is such a little fighter."
It was in May last year that Victoria Simmonds went into labour. Doctors could not halt it and frantically administered steroid injections to try to develop the baby's lungs. "I prayed that he would hang on," said Miss Simmonds.
Kaven - the name means "handsome" in Gaelic - was born within minutes of his mother's admission to Heath Hospital, Cardiff, and doctors did not think he would last through the night.
At five days old, he was diagnosed with the flesh-eating bug Necrotising-Fasciitis and needed emergency surgery to remove part of his bowel.
"We were so frightened for him," added his mother, whose 25-year old partner Lawrence Gainey is an IT project manager.
"We had him baptised before the operation, as the doctors didn't think he would be coming back. We just had to sit and pray that he would hang on."
The operation took nearly three hours but Kaven's battle still wasn't over. Scans revealed his ribs and legs were broken.
Miss Simmonds said: "He was so fragile, the doctors thought his legs had been broken just by lifting his legs up to change his nappy.
Kaven had an operation to close a heart valve in July, followed by laser treatment to save his sight after blood vessels failed to develop his eyes.
He is now ten months old and weighs 15Ib. He has just moved into clothes for three-month babies, and he will have to have physiotherapy until the age of five.
Miss Simmonds said: "He is so tiny that some people think he is new-born. But he's doing fantastically well and we are so thrilled with his progress."
Kaven was born only eight days later than the world's most premature surviving baby, Amillia Taylor, who was born last year in Florida at 21 weeks and six days.
Their survival will further fuel the debate over abortion laws, which still allow pregnancies to be terminated for non-medical reasons up to 24 weeks.