The beaming 30-year-old could be seen in the beautiful offering as she posed alongside her partner Harry Brooks.
The ultrasound scan of the retained prospective parent captures the image that appeared to have been captured in his car.
Sophie captioned the special message: “13 weeks and AF tired !!! Bring May 2021 !! “
A number of kind comments were posted under the ad – including one from Katie’s ex-husband Kieran Hayler.
Kieran – who shares two children with Katie – wrote: “Omg congratulations soph and @ harrybrooks88″.
Kerry Katona wrote: “Congratulations Omg my dear. ”
Others added: “Loveeeeeeeeee this So happy for you SophieChambres à vous deux belles nouvelles” and “Big bravo xx”
Sophie – who works for the BBC’s Children in Need in London – graduated last year after completing her Masters.
She and Katie, 42, share mom Amy but they have different fathers.
Sophie’s little one will have plenty of adored cousins as Katie is the mother of five – Harvey, Princess, Junior, Jett and Bunny – whom she shares with three of her former partners.
And Katie wants a sixth child with her new boyfriend Carl Woods, she recently said in pictures shared on her YouTube channel.
Katie told her followers, as she prepared to take a pregnancy test, “We want a baby and we’re not careful. ”
“This result – if I’m brilliant then. Otherwise, we’ll just try next month. ”
In the footage, the cheerful car salesman turned out to be just as exciting as his girlfriend was the mother of what would be his first child.
He said, “The result has come. Am I going to be a dad? Is Kate going to have her sixth child? ”
Katie announced that she was not pregnant with her fans on her YouTube channel.
She announced: “Not pregnant”.
She was quick to reassure her fans that everyone will know when she is pregnant.
Katie added, “What bothers me is that sometimes I say we have something to reveal, people always assume it’s a baby.
“Because we talked about ovulation, if we get pregnant we will have it. But people think it’s a ploy that I’m already pregnant. “