The last photo the couple shared of Jack was in August, 2018.
Posting a black-and-white photo to her 8.9 million followers, Rosie and Jason were dressed for a night on the town while Jack clung on to his dads leg.
“Fam…Dads movie premiere. So proud of you j”, Rosie wrote at the time.
The couple are currently engaged but in no rush to get married, having been together since 2010.
“I think the time will come. We’ve been so focused on our work for so long, and Jack came along. We definitely talk about it, we’re looking forward to that time, it’s also not a huge priority for us, we’re so happy,” Rosie told Extra last year.