Cate Blanchett and husband Andrew Upton have adopted a daughter.

The couple, who have three sons, Dashiell, 13, Roman, 10, and Ignatius, six, confirmed they recently became the proud parents of a newborn baby girl.

A spokesperson for the 45-year-old 'Cinderella' actress said: ''The Upton family (Cate Blanchett and Andrew Upton) have adopted a baby girl. No further details will be provided.''

The Oscar-winning actress first sparked rumours she had become a mother for the fourth time after being spotted holding the newborn while collecting her sons from school in Sydney earlier this week.

A source close to the star told Women's Weekly magazine in Australia that the duo have named the tot Vivienne.

The insider said: ''She's really excited and clearly besotted.''

The 'Blue Jasmine' star previously admitted she wanted a bigger family.

Speaking to InStyle magazine in 2009, she said: ''I'd love to have more children. Just when, I don't know. But the thing is, we hadn't planned any of the others. They just popped out. So you shouldn't over-plan these things. If it happens, it would be great.''

The Australian actress also opened up about juggling her career and motherhood in the past, and insisted she always puts her family first.

She said: ''It has to work for my family, otherwise I can't do the job.''