British actress Emily married US actor John three years ago and they both said to be "excited" about their impending arrival.
Emily's rep confirmed the news to American magazine Us Weekly, with a source adding: "They both couldn't be more excited."
Emily, 30, and 33-year-old John tied the knot in Italy in July 2010 - one year after getting engaged - and have made no secret of their desire to start a family together.
In a recent interview, Emily, who starred in The Devil Wears Prada, explained: "We want to have children; I just don't know when yet.
"We're both from big families, so I think it's something we want."
Emily and John were spotted just two weeks ago while walking through LAX Airport in Los Angeles.
At the time, Emily was wearing a baggy jumper over comfy purple trousers and John held her hand as they made their way through the crowds.
See who else is expecting in our gallery of pregnant stars below:
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