He was given almost no chance of survival when his mother Kerry went into labour just 23 weeks into her pregnancy.
There was so little hope, the 30-year-old was asked if she wanted a post-mortem examination carried out on her baby, just before she gave birth.
But Ashton, who could fit cupped in the palms of his mother's hands, showed his determination to live when he was born "kicking and screaming". He even lifted his arm as if to give his parents the "thumbs up" before he was whisked away to intensive care.
Now after five months clinging to life in two different hospitals, weeks on a ventilator, 10 blood transfusions, two bleeds to his brain, and a string of infections, Ashton is finally home with his parents Kerry and Sam.
He also survived major heart surgery to close a duct at three weeks old, when he still weighed less than 2lb.
Mrs McPhee, from Renfrew, Renfrewshire, said: "He is an absolute miracle. Words can't describe how amazing it is to have him home. All our dreams have come true.
"There's no doubt, he was definitely meant to be here.
"When he was born, he cried and I could see his arms and legs moving. He literally came out kicking and screaming. I call him my little lion cub, because he is so courageous and so brave."
But she added: "When he was born he was so minute, he just looked like a wee red Jelly Baby. His skin was red and translucent. I could see all his blood vessels."
After going into labour just halfway through her pregnancy however, doctors held out little hope of her baby surviving being born so early.
But on April 22, 17 weeks before his due date of August 19, Ashton was born at the Southern General Hospital in Glasgow at just 23 weeks gestation.
He was so tiny, he had to be placed in a plastic bag to keep him warm and was given just 11% chance of surviving.
Mrs McPhee, a call handler at the Scottish Ambulance Service, said: "I felt like lightning had struck twice because the year before we lost our daughter, Freya, at 19 weeks.
"With Freya an infection caused my waters to break but with Ashton my waters were still intact. I had an incompetent cervix.
"Before he was born they asked if I wanted them to do a post-mortem on him. It was between contractions when I was in full labour, which shocked us and is something that will stick in my mind forever. It was terrifying.
"But he had a really strong heartbeat and I knew he was strong. When I heard him cry I knew he was breathing on his own. We knew statistically that the odds were stacked against him, but there was still a little bit of hope and that's what we were clinging to."
Medics spent half an hour working on the baby as his parents watched on helplessly. He was then taken to intensive care, placed on a ventilator, and spent the next five months battling for life in an incubator.
Ashton now weighs a much healthier 11lb and measures more than 20 inches long.
He is still on oxygen, which he will remain on throughout the winter months, as he suffers from chronic lung disease. But doctors are positive Ashton's lungs will become stronger as he grows and he will eventually be able to come off all breathing aids.