Olivia Wilde is expecting a baby boy.

The 29-year-old actress - who is six months pregnant with her first child with fiancé Jason Sudeikis - accidentally revealed the gender of the unborn tot during the 71st Annual Golden Globe Awards on Sunday (12.01.14), by announcing how active he had been.

She told E! News: ''He was kicking the whole time, going, 'Where are we?!'''

The blonde beauty - who had covered the bump in a sparkling Valentino gown for the event - is loving her pregnancy body as she's developed bigger boobs.

She explained: ''It's great--I've never had boobs before!''

However, she has been slightly annoyed with her changing figure because people kept thinking she had just put on some extra pounds, instead of realising she was expecting a baby.

She told PEOPLE magazine: ''Until about a week ago, I just looked fat! I wanted to be like, 'I'm not fat, I'm pregnant!'

''I find that people will go to such great lengths to not mention it. People will be like, 'Hey would you like a glass of whiskey?' Or, 'You want to get on this roller coaster?' And I'm like, 'Oh well I'm actually pregnant.' And they go, 'What!?'

''I think it's because unless someone is watching you give birth they don't want to make the wrong call, because that's the worst thing in the world - when you congratulate a non-pregnant woman on her pregnancy.''