"'Think I just got a brief look into my future,' he captioned the photo of a beaming Jules, happily feeding the baby.
He then cheekily added: "PS: @JulesRobinson Not pregnant."
Fans of the couple were quick to post comments.
One fan commented: "Not yet, but you guys will rock parenthood."
Another wrote: "You will be a beautiful mumma."
Cam and Jules met on season six of Married at First Sight, and were one of only two couples to stay together after the show.
The couple were set to tie the knot this month, after Cam proposed for real at the end of the TV show, however they recently postponed their wedding.
Speaking to Ben Fordham on the Today show, Jules revealed the reason for the delay.
"We had this great idea to get married on the one-year anniversary, and it was just a lovely, romantic gesture," she said. "But so much has been happening and going on, and I wanted to enjoy the process of organising the wedding, so that's the only reason why it's been postponed."
The former MAFS star said there was no other reason for their change of plans.
"It's purely just because of that!" she confirmed. "Just wanted to organise the wedding and do it with enjoyment and not being stressed out by the whole process."