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.
She married director Jim Threapleton in 1998 and two years later the couple had a daughter, Mia.
Following their split in 2001 Winslet began a relationship with American Beauty director Sam Mendes, and they married in 2003. Their son Joe was born the same year and the couple separated in 2010.
Winslet made her film debut in 1994's Heavenly Creatures and received her first Oscar nomination the following year for her portrayal of Marianne Dashwood in the adaptation of Jane Austen's Sense And Sensibility.
But it was her role as Rose DeWitt Bukater alongside Leonardo DiCaprio in the 1997 blockbuster Titanic that propelled her to the top of the Hollywood tree, garnering her a second Academy Award nomination.
Winslet finally won the golden statuette in 2008 for The Reader after her sixth nomination, and was awarded a CBE for services to drama last year.