Bridesmaids star Chris O'Dowd told fans he is preparing to become a first-time father while taking the Als Ice Bucket Challenge on Wednesday (27Aug14).

The actor posted a video of himself on accepting the task from "a bunch of b**ody idiots" who nominated him to douse freezing cold water over his head in an effort to raise funds and awareness for the Als Association.

After his wife, Dawn O'Porter, drenched her husband with the water, he nominated his The IT Crowd co-star Richard Ayoade and "Baby O'Porter", as he panned the camera over to his wife who revealed her baby bump and poured a small cup of ice water on her burgeoning belly.

This will be the first child for the couple, which tied the knot in 2012.

Dozens of stars have now taken part in the water stunt campaign, which aims to raise awareness of Als, also known as Lou Gehrig's disease and motor neurone disease.