Credit: Mike Marsland/

Savannah Miller can't wait to be an aunt!

Sienna Miller's sister confirmed Us Weekly's exclusive news Friday on Twitter that the actress is pregnant. When one fan told Savannah there is "no greater feeling than welcoming a new life into the world in the comfort of home," she thanked her.

The New Year's Eve star's sister also tweeted that she was "thrilled!" Us was the first to break the news Friday that Sienna and boyfriend Tom Sturridge are expecting their first child. 

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 said.

A source told Us that Sienna'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. 

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