Oscar's mum Kirsten Varhalamas and his doctor Simon Newell say how extraordinary Oscar's progress has been.
Oscar, now five, from East Yorkshire, was born more than three months premature.
These are the extraordinary pictures of a premature baby born more than three months early.
Oscar Varhalamas, from East Yorkshire, is now five - and featuring in our special series on the NHS at 65-years-old.
Oscar's parents have created a picture book charting the first few months of his life, and have given it to the neonatal unit in St James' Hospital where he was treated, to inspire the parents of other premature babies.