Kate Winslet has reportedly named her newborn son Bear.
The Titanic actress, 38, gave birth to her third child, her first with husband Ned Rocknroll, in a Sussex hospital earlier this month.
Bear has taken his mother's surname unlike Winslet's two other children who took the name of their respective fathers, according to The Sun (£).
Winslet married RocknRoll, the nephew of Virgin tycoon Sir Richard Branson, in New York last December.
Kate Winslet is "doing great" after giving birth to a baby boy on Saturday, according to a spokeswoman for the star.
The actress had the baby, her first child with new husband Ned RocknRoll, at an NHS hospital in Sussex. A spokeswoman said: "Mother and baby are doing great."
The actress married Mr RocknRoll, the nephew of Virgin tycoon Sir Richard Branson, in New York last December, almost 18 months after they met.
She has two children from her two previous marriages.
Actress Kate Winslet and her husband Ned Rocknroll are celebrating following the birth of their first child together - a baby boy.
Winslet and Rocknroll - the nephew of Virgin tycoon Richard Branson, welcomed a nine-pound boy into the world at a hospital in Sussex.
A spokesman for the actress told The Daily Mirror: "Mother and baby are doing great."
Kate Winslet's Labor Day came early as the heavily pregnant star lit up the red carpet at the premiere of her new movie tonight.
Winslet was promoting tense drama Labor Day at the BFI London Film Festival and walked the carpet greeting fans, despite being weeks away from her due date.
The actress said, "I haven't had many cravings. I've been wanting to drink a lot of orange juice but I don't know if that is part of it."
Asked whether she would be taking a long maternity leave, Winslet replied, "Err... Ask me that on a different red carpet, I've got pregnancy brain!"
Actress Kate Winslet is expecting her first child with new husband Ned Rocknroll.
The pair will greet their new arrival at the end of the year, Winslet's publicist Sara Keene said.
"I can confirm Kate Winslet is pregnant and she and Ned Rocknroll are thrilled," she said.
"The baby is due at the end of the year."
The 37-year-old actress married Mr Rocknroll, 34, the nephew of Virgin tycoon Sir Richard Branson, in New York in December, almost 18 months after they met.
The Oscar winner has two children from her two previous marriages.
She married director Jim Threapleton in 1998 and two years later the couple had a daughter, Mia, now 12.
Following their split in 2001, Winslet began a relationship with American Beauty director Sam Mendes, and they married in 2003. Their son Joe, nine, was born the same year and the couple separated in 2010.
Kate Winslet and Ned RocknRoll have explained why they sought legal action to prevent "embarrassing" photos of him at a fancy dress party from being published in the press.
The couple issued a statement after a High Court judge blocked The Sun from printing the images from 2010.
A High Court hearing will continue tomorrow on the bid by the new husband of Oscar-winning actress Kate Winslet to stop The Sun printing photographs taken at a private fancy dress party with an "outrageous" theme.
Lawyers for Ned RocknRoll said there is no public interest in publishing the images and that he had been a "relative nobody" prior to his marriage.
The paper argues he has "propelled" himself into the position of "public figure".
The judge was told that photographs had been posted on a Facebook page belonging to Mr RocknRoll's friend.
He heard that Mr RocknRoll had been wearing a costume and could be seen "partly naked".
Kate Winslet's new husband Ned RocknRoll has today asked a High Court judge to stop The Sun from publishing old photographs of him at an "outrageous"-themed fancy dress party.
Mr RocknRoll, who changed his birth name of Abel Smith in 2008, said there was no public interest in the tabloid printing the private pictures, which were taken more than two years ago, as he was not a role model and was a "relative nobody" at the time.
Lawyers for The Sun are expected to contest Mr RocknRoll's application later today.
The newspaper said Mr RocknRoll, a marketing consultant and nephew of tycoon Sir Richard Branson, obtained a temporary injunction last week.