Actress Zoe Saldana has finally acknowledged the fact she is pregnant by refusing to take the ALS Ice Bucket Challenge.

The movie star was nominated by her Guardians of the Galaxy director James Gunn, but in a poolside video posted online on Tuesday (19Aug14), she explained she was in no condition to have freezing water tipped over her head and instead let her new husband Marco Perego take the plunge.

Rubbing her bulging belly, the mum-to-be said, "Obviously I can't do it myself so I nominate my husband to take on the challenge."

Saldana then nominated her Avatar director James Cameron, pals Salma Hayek and Aileen Getty and businessman Ron Burkle.

Reports suggest the actress is expecting twins later this year (14). She and Perego wed last summer (13).

Celebrities including Ben Affleck, Justin Bieber, Selena Gomez, Hugh Jackman and Justin Timberlake all recently took the Ice Bucket Challenge to raise cash and awareness for charity the ALS Association.