Sarah and Chris Cookson used the tragedy of losing their first son to set up a charity, the Charlie Cookson Foundation, which supports other families facing life-threatening conditions.
They were overjoyed when Sarah, 44, gave birth to a second son, on Boxing Day, but quickly had to face up to fresh heartache as their second baby, Carter, fights for his life.
He has serious problems with his heart, and after an operation last week to fit a pacemaker was unsuccessful, they have been told his only hope of survival is a heart transplant.
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Doctors at the Freeman Hospital in Newcastle told the family a new heart needs to be found for Carter in the next five weeks, prompting them to launch their #findaheartforcarter campaign.
Today, South Shields MP Emma Lewell-Buck backed their campaign by raising the tot's plight at Prime Minister's Questions in the House of Commons.
She told the House: "My constituents Sarah and Chris Cookson lost their little boy Charlie in 2013.
"Since then they have devoted their lives to helping other families and children with life-limiting conditions via their charity, the Charlie Cookson Foundation.
"On Boxing Day they gave birth to Carter John Cookson. He had three cardiac arrests in one day.
"After an unsuccessful operation he is now fighting for his life and in need of a heart transplant.
"Carter's only been given a matter of weeks to live. Will the Prime Minister join me today in raising awareness to help us find a heart for little baby Carter?"
Mrs May responded by commending the work the Cooksons have done with the Charlie Cookson Foundation in raising funds for those children and babies with life-threatening conditions.
"I am sure the sympathies of the whole House are with the family at this very, very difficult time.
"What I will do is ensure that the relevant minister at the Department of Health and Social Care meets the honourable lady (Mrs Lewell-Buck) to discuss this issue further.
"We do want to change the culture on organ donation to save more lives.
"That's why we are planning to introduce the new opt-out system in England from 2020.
"The new law will be known as Max and Keira's Law, in honour of Max Johnson, who received a new heart from Keira Ball, who sadly lost her life in a car accident.
"It's a tragic case that the honourable lady has outlined, and I'll ensure that the minister from the department speaks with her about it."