LITTLE Jack 'Sparrow' skipped the third trimester and weighed just 693g at birth.
The tiny newborn captured hearts across the nation when hundreds of friends, family and strangers donated nearly $50,000 after he was born at 24 weeks and five days gestation ‒ an incredible 15 weeks early ‒ on January 21.
Sadly however, the teeny newborn died on Friday after battling for his life at The Royal's Neonatal Intensive Care Unit (NICU) for 40 days.
His father Brendan Sadgrove posted a touching tribute to his "little bloke [that] has changed the world" on Facebook.
"I am so sorry to tell you all this way, but Jack didn't make it.
"He passed away on his Mummy's chest this afternoon about 3:30pm," Mr Sadgrove wrote.
He said they saw it coming after receiving a call in the early hours of Friday morning to say he had deteriorated.
"...from then on he just got worse and worse. The doctors tried everything, and I mean everything. They were just incredible.
"But we could see the direction things were heading early on in the day. He was just so so sick.
"Little Jack got to a point where we all thought he wouldn't come back from, so we decided to put him on Amy's chest and say our good bye's."
Mr Sadgrove said as soon as they did this his "heart rate and oxygenation immediately increased up to normal levels" giving them "a whole hour of the most amazing time with just the three of us" which he described as "nothing short of incredible".
"It was the happiest time in our lives.
"We had the most amazing time with him today, and we both experienced the happiest moment of our lives.
"The little bloke has changed the world. He has given us so much in such a short amount of time. I can't tell you the love that we have for our son."
The couple insist they are doing well but said even though they saw it coming it doesn't make it much easier.
"Love is what Jack gave us and we gave every bit of our love to him. I am so thankful for that."
Earlier, Mr Sadgrove and his wife Amy told the Southern Courier they feel as though they are strapped into a "rollercoaster" as they spent their days by Jack's bedside.
"He had been doing really well up until two weeks ago," Mr Sadgrove said. "He had kidney failure. His kidney stopped working for a day or so."
Jack had been "growing slowly" and weighed 1kg. It was expected he would be kept in the NICU at least until his due date on May 8.
In his post, Mr Sadgrove shared a photo of himself, Amy and Jack.
"This is a photo we took during his last last hour on Mum.
"I will cherish that time with him forever. He passed away in our arms and it was very beautiful and peaceful."
He said they then gave him his first bath, put some clothes on him for the first time, swaddled him for the first time, and then tucked him in.
"Nigh night Jack. Your Mum and Dad love you more than anything they could have ever imagined."
According to Jack's GoFundMe page, all the money raised in his name is now "in honour of all of the sparrows in the nest" at the Royal Hospital for Women, Randwick.