Paltrow misses Proof promotion in Venice
She missed the film's press conference, which was attended by co-stars Sir Anthony Hopkins and Jake Gyllenhaal, and instead joined via a telephone link.
Speaking about her future, Paltrow commented: "At this point in my life I'm only interested in doing a role that I feel I'm going to learn something from, that's going to challenge and enrich me as an artist, a person, a mother.
"I don't have that carefree spontaneity any more. I can't just pick up at the last minute and go to a remote location because there's so much to consider."
Hopkins meanwhile said that along with Jodie Foster, Paltrow was the best actress he had worked with.
Proof is directed by John Madden, the man behind Shakespeare In Love and Captain Corelli's Mandolin.
It is based on the Pulitzer Prize-winning play by David Auburn, in which Paltrow appeared at London's West End in 2002.
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