Zoe Saldana

Zoe Saldana

Zoe Saldana avoided doing the ALS Ice Bucket Challenge because of her pregnancy.

The 'Guardians of the Galaxy' beauty, who is rumoured to be expecting twins, acknowledged for the first time she is set to become a mother before nominating her husband, Marco Perego, to take her place and complete the task by having freezing water poured over his head to raise awareness for the nerve cells disease.

Turning to the side and rubbing her growing baby bump, the 36-year-old actress, who was nominated by director James Gunn, said in a video of the event: "I am accepting James Gunn's challenge to take on the ice bucket challenge.

"Obviously, I can't do it myself so I nominate my husband to take on the challenge and get rinsed with a nice bucket of ice water."

After pouring ice cubes and water over artist Marco's head, the actress nominated four people, including James Cameron and Salma Hayek, to take on the challenge next.

Zoe has been tight-lipped about her pregnancy until now and a source previously said: "She will only announce the news when she's ready."

Another insider said that 'Avatar' star, who secretly married Marco in London last year, "has always wanted a big family."