A husband's heartbreaking tribute to his pregnant wife is going viral.

A father-to-be has shared a loving tribute to his wife who is carrying their unborn baby daughter – who is expected to live just days.

Royce Young’s wife Kerri, has chosen to go full term after being told her baby has no brain.

Kerri is carrying baby Eva to full term so that she can donate her daughter’s organs.

“In literally the worst moment of her life, finding out her baby was going to die, it took her less than a minute to think of someone else and how her selflessness could help,” Young said in his moving post on Love What Matters.

The smitten husband says he not only married his best friend but also a “truly remarkable, special human being”.

Listen: What do you say to someone who’s lost a baby? (post continues after podcast)

“I looked at her laying there, her belly big with our daughter kicking away, a daughter that won’t live more than a few days, and it just overwhelmed me how incredible this woman is,” he said.

The writer says he would change his circumstances if he could.

“I want my daughter to be perfect. I want her to blow out her candles on her first birthday. I want to watch her bang her head on our coffee table trying to learn to walk. I want her to run up a cell phone bill texting boys. I want to walk her down an aisle. I want to change it all so, so badly. But I can’t. This is our reality. And there’s no stopping it,” he said.

The pair face a harrowing journey to have their baby Eva but Young has every faith in his wife’s bravery.

“She’s tough. She’s brave. She’s incredible. She’s cut from a different cloth, combining wit, beauty, courage, silliness, character and integrity into one spectacular woman.

“And somehow, she’s my wife. Not that I needed some awful situation like this to actually see all of that, but what it did was make me want to tell everyone else about it.”