Urban and Kidman have been married for two years
Nicole Kidman's father has revealed he suggested naming his granddaughter Sunday, having been inspired by artist Sidney Nolan's muse Sunday Reed.
Speaking to Sydney's Daily Telegraph, Dr Antony Kidman said: "The name struck me as being a nice name for a woman, so my wife and I mentioned it."
Kidman and husband country singer Keith Urban welcomed Sunday Rose Kidman Urban into the world on Monday in the US.
Dr Kidman said Reed was a "key mover and shaker in the arts".
He added: "It was among other names being mentioned but they decided that was the name they wanted."
Reed was a well-known figure in Australia's art scene during the early 20th century, and spent the 1930s in a three-way love triangle with her arts patron husband, John, and painter Nolan.
The Telegraph said Kidman and Urban had shown a keen interest in an exhibition of Nolan's art during a recent trip to Sydney.
Amongst his paintings was a quote about birth: "When you are young you are given a good view of life, because of your closeness to birth."
Sunday is Kidman's first biological child.
The Moulin Rouge star adopted two children with Tom Cruise during their marriage, which ended in divorce in 2001.
She married Urban in 2006 at an evening ceremony in Sydney.