It sounds like that was what Kylie might have actually wanted at some point; the five kids that is, not necessarily the reason why. Jason confirmed that before they started having kids ...

Jason and Kylie Kelce haven ... “I’ve always said I wanted four kids [and] room for, like, one pleasant surprise,” she explained. “If we had five kids, I’d be like, ‘OK, that ...

You can always go for the starting five, though… [and], just go for … field an infield!" Travis said. Jason said that going for five kids was Kylie’s original plan.