Rebecca revealed the news to fans via Twitter on Sunday afternoon (13 April), saying that she is "grateful" to be expecting again.
She tweeted: "Yes I am having a new lovely baby. Children are such a blessing and I'm grateful to god for my new little gift xx."
Rebecca is already proud mum to two children, Lillie May and Karl, from a previous relationship.
The 27-year-old continued to gush about her unborn child, posting a photo of two swans, which read: "There's a little heart beating next to me."
In December, Rebecca revealed to The Mirror that she was dating a man who she had known for years, but was keeping his identity a secret.
She said: "We've been together a year now. He's lovely and he looks after the kids. He goes fishing with my son."
More celebrities who have announced pregnancies this year:
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