The 54-year-old predicted that the teenage heartthrob would "get on with" becoming a father and happily accept the responsibility.
"I don't think it'd bother him too much if he did get a girl pregnant," he told The People.
"He would be a responsible parent and just get on with it. I honestly think that's the way he would be."
However, Des clarified that he is not hoping to become a grandfather anytime soon, as a baby could potentially "screw up" One Direction's career.
"If that were to happen it would really screw things up big time," he argued. "From a One Direction aspect it wouldn't be great for all sorts of reasons."
It emerged this week that Styles had a three-month affair with married radio DJ Lucy Horobin, 32, last year when he was just 17.
Horobin has since received abuse from One Direction fans and allegedly quit Twitter after being called a "dirty paedophile" by users of the site.
Styles famously dated Xtra Factor host Caroline Flack, who was also 15 years his senior during their relationship.