Speaking to Pamela Ballantine on Friday, Ms Foster said that Dr Paisley had made time to ask after her son Ben’s health, even while the DUP were negotiating the St Andrew’s Agreement in Scotland in 2006.
Ben was diagnosed with pulmonary stenosis not long after being born.
The condition signifies a problem with a valve in the heart and Ben required surgery to fix it.
Ms Foster said it was a stressful time coming so soon after the initial joy that marked her third child’s arrival.
“I was just about to leave hospital with Ben when I was told by the doctors that he had a problem with his heart, which hadn’t been detected when he was in the womb,” she said.
“It was a stressful time and he was rushed up to the Royal Victoria Hospital.
An unexpected call from her party colleagues however, gave her some strength at a time that every parent would fear.
“I remember very well taking Ben up to the theatre and he had to undergo anaesthetic and it was rather pathetic, this little tiny baby on a huge operating table and I felt very alone and upset,” she said.
“I went down to the canteen and the next thing there was a phonecall from Dr Paisley and all the team at St Andrews saying that they’d been thinking about me and I thought that was lovely.”
And Dr Paisley’s influence didn’t stop there, with the former DUP leader stepping in to ensure that an event organised by Ms Foster for the Heartbeat charity had maximum profile.
“David Healy, who was a patron of Tiny Life, agreed to come along very kindly, to do a fundraiser for Heartbeat,” she said.
“Roy Hodgson, who was the Fulham manager at the time, wasn’t going to allow him to leave, because Fulham weren’t having a great time at that moment.
“Dr Paisley had to intervene and ring him up and say ‘allow this man to come’.”
Family forms an important part of the DUP leader’s life and she said that it was fantastic to have her mother with her when she was officially made First Minister at Stormont.
“It was tremendous to have her there,” she said.
“The only sad thing about that day was that my father, who passed away four years ago, couldn’t be there because I was a bit of a daddy’s girl and it would have been lovely had he been there.”