The actress, most famous for playing Mandy Richardson in the Channel 4 soap, is to welcome her child with boyfriend Jonathan Smith.
She announced her baby joy to fans via Instagram in a photo where she cradled her baby bump.
Sarah, who is a fully qualified personal trainer, captioned the photo with a baby and heart emoji.
After being inundated with messages, Sarah said: "Thank you for all your lovely messages. We are super excited to become parents."
In February, Sarah gushed about boyfriend Jonathan, telling fans: "The reason every day gets better - my world. Luckiest lady alive. #happyvalentines @jonathn_smith."
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