The couple, who are yet to officially announce the birth, were spotted out and about in London with the newborn on Wednesday.
Pictures obtained by MailOnline show Whitmore clutching a tray of hot drinks as Stirling holds a car seat carrying the baby.
It is currently unclear when Whitmore gave birth but the Love Island host was absent from her BBC Radio 5 Live show on Sunday morning, with Stacey Dooley stepping in to present.
Yahoo has contacted Whitmore and Stirling’s representatives for comment.
After keeping her pregnancy under wraps for months, Whitmore announced in December that she was expecting a baby in “early 2021”.
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Posting a picture of a babygro on Instagram, she told fans: “A lot of things are just for me and my loved ones and we’ve chosen not to share publicly.
“However I want to now share good news as it’s our news to share - and I’m gonna be honest it’s starting to look like my lock down beer belly is out of control. Iain and I are expecting a baby early 2021.”
In the months since, she has shared numerous updates on social media and revealed the sex of the baby in an extract from her new book, published in the Irish Independent.
“There’s a new chapter coming in my life in the form of a baby girl currently growing inside me,” she wrote. “And that scares the s*** out of me.
“She will be supported and loved but she is the heroine of her own life, no-one else. We aren’t built to have it all figured out.”
Whitmore and Stirling tied the knot in secret last year, before sharing the happy news on Instagram on New Year's Day. The couple began dating in 2017.
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