Exclusive: Sienna Miller Is Pregnant!

Baby on board!

Sienna Miller and boyfriend Tom Sturridge are expecting a child, a source confirms to Us Weekly. The 30-year-old actress and Sturridge, 26, have been together for a year and "don't have plans right away to marry, if at all," the source says.

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"Friends are really happy with her relationship with Tom," the source tells Us. "He's younger, yes, but he's mature and he's a good guy."

The source adds that Miller's family "had had it with Jude Law and his cheating and all the back and forth." Last February, Miller and Law, 39, ended their relationship for the second time. They first split in 2006 after two years of dating when Law admitted to cheating on the star with his children's nanny.

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Miller and Sturridge's friends "were not surprised by the news of the pregnancy," says the source. "They're really good together."

"They just spent the holidays in Paris together after they announced the news in London," says the source.

Miller's rep could not be reached for comment. A rep for Sturridge tells Us: "We don't comment on our client's personal lives at all."

VIDEO: Inside Rob, Kristen, Tom and Sienna's double date

In September, the duo went on a double date with Sturridge's pal Robert Pattinson and girlfriend Kristen Stewart. The foursome knocked back drinks at London's Groucho Club. "They looked happy," a witness told Us.