Samantha Burke – the aspiring actress expecting Jude Law's baby – revealed the name and sex of the impending arrival as she held a press conference at her mother's house in Florida at the weekend.
"Samantha, her mum and her family can affirm Jude has been responsive and supportive throughout the relationship and pregnancy, and know that he will remain so once baby Sophia is born," the 24-year-old said in a statement.
She went on to request privacy from the media at this time.
It will be the fourth child for 36-year-old singleton Jude, who is already dad to sons Rafferty, 12, and Rudy, six, and his eight-year-old little girl Iris with his ex-wife Sadie Frost. He also has a stepson, Finlay, who is 18.
The London-born actor had a short-lived romance with Samantha last year while he was on location filming Guy Ritchie's Sherlock Holmes in New York.
And while the mum-to-be herself has paid testament to Jude's vow last week to "play a fully supportive" role in the child's life, it is being reported that the Hamlet star wants a paternity test so he can be completely confident the baby is his.
"At the moment Jude doesn’t know for sure he is the father. He thinks he is – but he wants to be 100 per cent certain," a friend told a Sunday paper.
"There has been a lot of speculation. But if it is his baby girl he'll be there for her every step of the way."