The 28-year-old X Factor star said she's come under pressure to be like the ping-back celebrities who instantly slim down after having a baby, but she's refused to comply because she's 'happy in my own skin'.
Rebecca gave birth to Arabella on October 25 and is also mum to Lillie May, nine, and Karl, seven, from a previous relationship.
Rebecca said: "I'm really happy in my own skin, it's other people who aren't happy.
"People say 'Oh, Becky don't you want to lose a few pounds', and I'm like 'I'm really content, I'm the happiest I've ever been'.
"It's funny how the world [perceives] how you should be after pregnancy now, they think you should snap back into shape especially if you're in the public eye.
"I say it's OK to enjoy your baby."
She said: "Having a baby has changed me as a person as I'm not interested in going out with the girls.
"I think all new mothers are like that really, it goes on the back seat. I think Arabella has completed me she made me grow up, she made me value myself."
More on Parentdish: How to boost your post-baby body confidence (without a crash diet)
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