When Ryan Marquiss was born with his heart outside of his body, doctors didn't expect him to survive.
The incredibly rare defect ectopia cordis affects only eight in every million births and 90 per cent of these are stillborn or die within three days.
Ryan was also suffering from hypoplastic right heart syndrome, where only the left side of the heart has developed properly - a combination of defects that is so rare that Ryan is the only one of his kind in the world.
Doctors advised his devastated parents, Leighann and Henry to terminate the pregnancy when they discovered the problem at 12 weeks, but they bravely refused.
And it is a gamble that has paid off, as Ryan is just about to celebrate his third birthday.
Leighann, 34, who lives with husband Henry, 34, and their other children Natalie, seven, and Ainsley, five, in Pennsylvania, USA says: "We wanted to let nature take its course, so we refused to have the termination. We knew it would be a miracle if he survived the birth but we were unwilling to take matters into our own hands.
"The doctors told us that no baby with Ryan's combination of defects had ever survived, so the fact that he is here with us today is just amazing. He really has astounded everyone.
"All the odds were stacked against him. We knew that it was a miracle that he had been born alive with his heart outside his body, but then to have another life-threatening condition of only having half a heart meant that everything was against him surviving."
Doctors at the Children's National Medical Centre in Washington delivered Ryan at the end of February 2009 by Caesarean, helped by a team of 30 medical professionals.
Dr Mary Donofrio, Director of the fetal heart programme at the Children's National Medical Centre says: "If he survived the birth his exposed heart likely would become infected and kill him. Even if infection didn't happen his heart had one working ventricle and he would require open heart surgery to rewire the blood flow through it.
I told the family right from the start that if he survived, it was a miracle.
"His heart was protruding out of his chest cavity. The heart was only covered by a thin membrane," explains Leighann.
"But he was alive and we just had to pray that he would carry on fighting."
Ryan had to have an operation at just two weeks old to have a central shunt placed in his heart to ensure proper blood flow.
Then he underwent more than a dozen operations over the next two years. He had operations to re-plumb his heart so that the half a heart would do the job of a full size heart. Doctors also put tissue expanders under his skin to produce more skin so they could use it to cover his exposed heart.
"He has done amazingly well," says Leighann. "He has been so brave throughout it, and his sisters have kept him going too. They have been to see him in hospital and made recordings of themselves at home, so Ryan could hear them.
He just kept on fighting. He refused to die, and he kept on proving everyone wrong. He will need some sort of chest protection operation in the future but it may be overcome by just wearing some sort of protective padding when he plays sport.
"He won't be a competition athlete, but we are hoping he can run around on the playground and climb trees like any other child."
Ryan's case has now been reported in a medical journal, and doctors believe that his survival offers hope for other babies with serious heart defects.
In the future he may require a heart transplant, but at the moment, he is progressing well.
"He really is a medical miracle," says Leighann. "When I look at him running around the playground and playing on the climbing wall, I praise God. Every day with Ryan is one we were told we wouldn't have. So we cherish each moment.'
Follow Ryan's progress at Marquissclan.blogspot.com.
What an amazing story. Good luck Ryan!