A "miracle baby" who was not expected to live after three open-heart surgeries has started school this week.
Mason Astley's parents Heidi and Trevor Astley were warned to prepare for "the worst" after he needed open-heart surgery just days after being born, and caught an infection which doctors could not initially diagnose.
He spent 12 days on a machine which replaced his heart, and was in intensive care at Starship Children's Hospital for 46 days.
Even after he survived three operations, his parents were warned that he had suffered brain damage and was at risk of developing cerebral palsy.
But when he started at Gladstone School in Mt Albert this week, he was a normal 5-year-old.
"He has been completely engrossed in everything we've been doing. He has listened and participated just as much as the other children," said his teacher Abby Hunt.
To his parents, it's a miracle.
"The unknown is when you pick up an infection post-surgery, and that just led to another series of issues which went on to the point where we were told to expect the worst, and then he turned a corner, so he really is a miracle," his dad said.
"He's a million-dollar baby," his mum said. "The amount of resources that the hospital gave him, the number of days he was in intensive care, the number of surgeries he had that kept rolling on, with more and more equipment to bolt on to him that was keeping him alive."
Starship cardiologist Professor Jon Skinner said the heart/lung bypass machine alone cost "thousands of dollars every day".
"What he is is a successful product of a huge investment by a very good health system," Skinner said.
"I don't like to use the word 'miracle', but it is an amazing feat of medical science that one can support a heart, a brain and a body for two weeks while the heart is recovering."
Trevor Astley said that after Mason finally came home, the doctors still did not know how much brain damage he might have suffered.
"They said there could be anything from developmental delay to he might not walk, he might not speak properly," he said.
"When he crawled, when he walked, when he talked, they were all important, and that was another one yesterday when he started school."
Heidi Astley said: "He's always had to catch up a bit, but he met all his milestones. He has grown into his own personality, he's very determined, very stubborn."
The couple has had huge support from extended family. Trevor Astley works in the family business and was able to stop work and move with Heidi and their two older boys into his parents' home while Mason was at Starship and for a while afterwards.
"Life was good, but that burst our bubble, it was like a rollercoaster," said Heidi.
"But it has got easier and easier, basically because we have provided him with a happy, busy life with his brothers and with broader family and friends."
Mason has had recent eye surgery, still receives speech/language therapy, and is likely to need further heart surgery in his teens.
"In the meantime he can lead a fairly normal, active childhood, but he has to avoid contact sports," his dad said.
"Any sort of rugby-type accident could be very detrimental. He's at risk of something called aortic dissection where your exit valve could detach from the heart, which could be fatal."
"Right from the get-go his cardiologist said he won't be an All Black. But there are plenty of other things to engage in, whether it's musical or creative or anything."
Heidi Astley said the family was just grateful that Mason survived.
"There was another baby who died while we were at Starship, I'll never forget that mother's screams," she said.
Trevor Astley said Mason "wouldn't be here today without the Starship team".
"We can't sing high enough praise for Starship."