Sienna Miller and Tom Sturridge are expecting their first child

Sienna Miller is expecting her first child with boyfriend Tom Sturridge.

Sienna Miller, 30, who has been dating actor Tom Sturridge for just over a year, is believed to have broken the news to friends and family just before Christmas.

The actress’ sister, Savannah Miller, tweeted today: “THRILLED.”

A source told Us Weekly that Sienna Miller and Tom Sturridge “don’t have plans right away to marry, if at all”.

“Friends are really happy with her relationship with Tom. He’s younger, yes, but he’s mature and he’s a good guy,” the source added.

Allegedly Sienna Miller’s family were sick of the actress’ going back to actor Jude Law and are thrilled with the news.

Sienna Miller and Jude Law, 39, called time on their relationship in February.

The pair’s first split was in 2006 after two years of dating when Jude Law admitted to cheating on the star with his children’s nanny.

Sienna Miller and Tom Sturridge’s friends reportedly said they were not surprised by the news of the pregnancy.

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

A representative for Tom Sturridge tells Us Weekly: “We don’t comment on our client’s personal lives at all.”

Sienna Miller’s agent was not available for comment.