Chris O'Dowd and Dawn O'Porter are expecting their first child.

Upon completing the challenge, which involves pouring a bucket of freezing cold water over his head to raise awareness and funds for Lou Gehrig's disease, the Irish star said: "I'd like to nominate Richard Ayoade, Graham Linehan and Baby O'Porter. So brave."

He then panned the camera over to TV presenter Dawn, who shrieked as she poured a small glass of ice cubes and water over her baby bump.

Shortly after Chris posted the footage, the British star acknowledged the happy news on Twitter, writing: "Thought we'd better mention it, before I got O'Busted (sic)!"

The 'IT Crowd' star married author Dawn, 35, in a low-key ceremony in June 2012 and she previously admitted feeling under pressure to start a family.

She said: "I think it's a really natural question to ask and I totally understand why people do.

"But I get slightly shirty because Chris could do seven interviews on the trot and not get asked once about me or if we're going to have kids."

The couple first met through mutual friends at the brunette beauty's 30th birthday party in Los Angeles.