The 42-year-old tweeted a picture of her baby bump and said: "I'm so pleased to tell you all... I'm expecting my first child with my wonderful boyfriend Adrian!!
"I've always wanted to be a mum and didn't think I could have children.
"And now, at the ripe old age of 42 - I'M PREGNANT! We couldn't be happier."
The actress also posted about her pregnancy on Instagram.
Fellow Corrie actress Jennie McAlpine welcomed the "lovely news" on Twitter, along with many of the actress's fans.
Tamaddon is now starring in the West End show Everybody's Talking About Jamie, but is best known for playing Delilah Dingle on Emmerdale between 2005 and 2007, as well as Andrea Beckett on Coronation Street between 2013 and 2015.
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