Sienna Miller and fiance Tom Sturridge, star of The Boat That Rocked, have reportedly welcomed their first child into the world this weekend in London, according to a report in Us Weekly.

The English actress, famous for her roles in Alfie, Layer Cake, G.I Joe and Factory Girl, is notoriously private, so it’s no surprise that at the moment the sex or name of the baby are unknown.

Ms Miller’s previous engagement, to Alfie co-star Jude Law, ended in 2005.

Her relationship with 26-year-old Sturridge began just over a year ago.

Ms Miller hasn’t spoken very much publicly about her pregnancy, but did touch on the subject briefly in an interview with Vogue UK in April.

She told the fashion magazine: “I'm feeling fine. It's all progressing nicely and it's very exciting."

The fiercely private star has also given her baby bump a few public outings this year, including to Restaurant Gordon Ramsay in London with Sturridge, for his pal Robert Pattinson’s birthday slap-up, according to Us Weekly.

Besides acting and preparing for motherhood, Miller, recently, has also been taking a stand against the press. She was one of the celebrities who appeared at the Leveson inquiry and described her horror at being chased by paparazzi.

It’s thought she will receive a large payment from News International after The News Of The World admitted hacking into her phone.

More stars who are expecting babies in 2012:

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• Jessica Simpson

  Jessica announced that <a href="http://www.huffingtonpost.com/2012/12/25/jessica-simpson-pregnant-baby-maxwell-photo_n_2362558.html">she's expecting her second baby</a> on Christmas. She and fiance Eric Johnson have a seven-month-old daughter Maxwell.

• Kate Middleton

  The Duchess of Cambridge is <em>officially</em> expecting her first child with Prince William! The mom-to-be is <a href="http://www.huffingtonpost.com/2012/12/03/hyperemesis-gravidarum-kate-middleton-pregnant_n_2234099.html">suffering from Hyperemesis Gravidarium</a>, a rare maternity condition which brings on severe nausea, vomiting, weight loss, dehydration, lightheadedness and fainting.

• Fergie & Josh Duhamel

  The couple announced their baby news on Twitter Feb. 18, after weeks of speculation.

• Penelope Cruz

  The actress is expecting her second child with husband Javier Bardem. The couple already has a 2-year-old son Leo.

• Evan Rachel Wood

  The actress is <a href="http://www.huffingtonpost.com/2013/01/11/evan-rachel-wood-pregnant-jamie-bell_n_2456954.html">expecting a baby</a> with her new husband Jamie Bell.

• CaCee Cobb & Donald Faison

  Jessica Simpson's best friend Cacee Cobb and new husband Donald Faison are expecting their first child together. The couple of six years married in December in the backyard of Faison’s "Scrubs" co-star Zach Braff.

• Tracy Morgan

  The actor and comedian and his model fiancée Megan Wollover are expecting their first child together early this summer.

• Halle Berry

  Berry is expecting her first child -- a boy -- with fiance Olivier Martinez. She is already the proud mommy of 5-year-old daughter, Nahla.

• Jamie-Lynn Sigler

  Sigler and her brand new fiance Cutter Dykstra are expecting their first child together.

• Hilaria & Alec Baldwin

  The couple announced that <a href="http://celebritybabies.people.com/2013/02/12/alec-baldwin-hilaria-baldwin-pregnant-expecting-baby/">they're expecting their first child</a> together. Alec already has a 17-year-old daughter, Ireland, with ex Kim Basinger.

• Mario Lopez & Courtney Mazza

  The newlyweds are expecting their second child, Mario revealed. “I am the happiest father in the world," <a href="http://www.extratv.com/2013/02/19/mario-and-courtney-lopez-expecting-baby-no-2/">he told Extra</a>. "We cannot wait to welcome baby Lopez number two into our lives.”

• Mark-Paul Gosselaar

  The "Saved by the Bell" star and his wife Catriona McGinn are expecting their first child together this September. Gosselaar is already a dad to two kids -- son Michael, 9, and daughter Ava, 6 -- with ex-wife Lisa Ann Russell.

• Jamie Anne and Marshall Allman

  "The Killing" star and the "True Blood" actor are expecting twins in the spring of 2013.

• Busy Philipps

  The "Cougar Town" star is <a href="http://www.huffingtonpost.com/2012/12/10/busy-philipps-pregnant-cougar-town-star-expecting-second-child_n_2272754.html">expecting her second child</a> with husband Marc Silverstein.

• Heather Morris

  According to Us Weekly, Heather Morris, 26, and longtime beau Taylor Hubbell are expecting their first child.

• Ivanka Trump

  Trump and her husband Jared Kushner <a href="http://www.huffingtonpost.com/2013/04/11/ivanka-trump-pregnant-second_n_3060630.html?utm_hp_ref=celebrity" target="_blank">are expecting their second child</a> this fall.

• Sarah Wright

  Wright and her husband Eric Christian Olsen are expecting a baby boy in August, <a href="http://celebritybabies.people.com/2013/04/17/eric-christian-olsen-expecting-son/" target="_blank">People confirms</a>.

• Kyla Weber

  Vince Vaughn's wife <a href="http://www.huffingtonpost.com/2013/04/27/vince-vaughn-baby-actor-wife_n_3169237.html?utm_hp_ref=celebrity" target="_blank">is expecting the couple's second child</a> in August. The pair already has a daughter Locklyn.

• Jaime King

  The "Hart of Dixie" star is expecting her first child with husband Kyle Newman.

• Rachel Leigh Cook

  The "She's All That" star and her husband Daniel Gillies are expecting their first child this fall.

• Monica

  Monica is expecting her first child with husband Shannon Brown, but she's already mom to sons Rocko, who turns 8 later this month, and Romelo Montez, 5.

• Autumn Reeser

  The actress is expecting her second child.

• Jennifer Love Hewitt

  The "Client List" actress and her boyfriend, Brian Hallisay, are expecting a baby.

• Kate Winslet

  Winslet and her husband Ned Rocknroll are expecting their first child together.

• Kim Zolciak

  The "Real Housewife" is expecting her third child with husband Kroy Biermann.

• Stephen Amell

  The "Arrow" star and his wife Cassandra Jean are expecting their first child together.