The actress announced her happy baby news today, telling The Mirror that her whole family is "very excited" about welcoming a new arrival.
Olivia is married to author Ed Sinclair. The couple are already parents to nine-year-old son Finn and seven-year-old son Hal.
So far, they're keeping quiet on any further details such as the baby's sex, but Olivia has revealed she is craving Smarties sweets!
BAFTA-winning actress Olivia, 41, can currently be seen as DS Ellie Miller in ITV's Broadchurch, which is airing its second series.
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