Naomi Watts & Liev Schrieber at the Premiere of Talk Radio

Naomi Watts' pregnancy was the worst-kept secret in Hollywood after the designer of her Oscar dress let slip the news that she was expecting before an official announcement had been made. The actress was proudly showing off her baby bump in a softly draped, petrol blue number on Sunday night, though, as she stepped out to the theatre in New York.

Attending the premiere of boyfriend Liev Schreiber's Broadway play Talk Radio, the beautiful Mulholland Drive actress revealed her burgeoning bump in a slim-fitting emerald-blue dress. For the Oscars ceremony 36-year-old Naomi had chosen a cleverly draped pale yellow Escada gown, but on Sunday night the Australian actress left onlookers in no doubt that she was soon to become a mother for the first time.

Liev had officially confirmed the news on an American talkshow the previous week, telling the host: "Yes, I'm going to be a dad!", adding that the news was "very exciting". The 39-year-old actor, who met Naomi in 2005 while they were both filming The Painted Veil, said the couple had not decided on a name for the baby, and joked that he is "trying to stay out of it all".

"I'm trying not to make any decisions," he said. "I find everything I try to do in service of her or the coming baby is wrong." The actor did reveal that the pair won't be naming the baby after its father, however. "It's a terrible name. It's probably the most mispronounced name in all of showbusiness. It's bad enough that I have gone through that for 15 years. There won't be any Liev Juniors."