Sienna Miller reportedly insists she's a "changed woman" since becoming pregnant.

The actress is expecting her first child with boyfriend Tom Sturridge, who she has been dating for a nearly a year.

Sienna who is also reportedly engaged is said to have left her old lifestyle behind in a bid to move forward with family life.

"Sienna's mates were worried she'd rushed things with Tom, but she says she wants to be with him forever," a source told British magazine Closer.

"She insists she's a changed woman and is happy to leave her party days behind her. Now she's pregnant, she's ditched all her bad habits and is embracing her new life."

Sienna is famed for her love of partying and her affair with married Balthazar Getty three years ago. The stunning star split from her former fianc Jude Law for the second time early last year.