John Cena is ''changing [his] tune'' about having children.

The 40-year-old actor-and-wrestler has previously insisted he has no desire to have kids of his own with fiancee Nikki Bella, but the couple have had a number of ''lengthy and difficult'' conversations about the subject after it came to the forefront while promoting his new movie 'Blockers', in which he plays the parent of a teenage girl.

Discussing his anti-child stance, he said: ''Well, that statement is not from her, it's from me and it's just me being a stubborn idiot.

''Believe it or not, over the course of filming and promoting this film, the topic has come up so much.

''I didn't want to address it or talk about it but now we've had some lengthy - and honestly quite difficult - conversations about it but I'm changing my tune.''

While John clarified he and Nikki haven't yet begun trying for a baby, it could be on the cards one day.

Speaking on Australian radio's 'The Kyle & Jackie O Show', he said: ''I am very open to certainly explore the process, whereas before it was like 'Never, not a chance.' ''

Asked if that means he's softened and now wants to be a dad, he replied: ''Yes sir! and that right there is the power of love, my friend.''

Nikki admitted last April that she and her fiance wouldn't be having children of their own because her partner had no interest in starting a family.

Asked if babies would be in her future, the 34-year-old wrestler said: ''I've been getting that question a lot, let me tell you. No, there won't be.

''John doesn't want kids, so we're not gonna have kids.''