The parents of Charlie Gard, who was at the centre of a legal row over his treatment before he died, have said they have been "blessed" by the birth of another son.
Oliver Gard was born the day after what would have been Charlie's fourth birthday and has not inherited his brother's rare genetic condition.
Charlie died in 2017 after a legal bid for experimental treatment was refused.
Connie Yates and Chris Gard said: "We never thought we'd be happy again."
"As soon as I found out I was pregnant I felt happier, like I could smile again," Ms Yates told BBC Breakfast.
"I think before, I would plaster a smile on and say 'yeah I am OK' all the time. But now I feel I can smile and mean it."
Charlie had encephalomyopathic mitochondrial DNA depletion syndrome - a rare genetic condition - and died in a hospice aged 11 months.
Doctors at Great Ormond Street Hospital said he could not see, hear or move and had irreversible brain damage.
They argued it was not clear if he could feel pain and said he should be allowed to die with dignity, but Charlie's parents fought for him to be given an experimental treatment in the US.
Mr Gard said: "After we lost Charlie I just felt like a part of us died with him."
"We will always live the 'what if Charlie was given the treatment?'
"After I lost Charlie I didn't think I could love another boy like I did him.
"So when he [Oliver] was born a lot of it was relief, because I felt like I did with Charlie and just this instant rush of love."
There was a chance Oliver, who was born on 5 August, might also have Charlie's rare genetic condition but he was born healthy.
Ms Yates' contractions began on what would have been Charlie's birthday at about the time Charlie was born, Mr Gard said.
"I just feel that Charlie has had a massive part to play in making his brother healthy."