Baby No 1 on the Way for Olivia Wilde and Jason Sudeikis

Hollywood is gearing up for another celebrity baby! Olivia Wilde and fiancé Jason Sudeikis are expecting their first child.

"They are incredibly happy," a source close to the couple confirmed the news to People magazine. "They're very excited to welcome a new member into their family."

Olivia and Jason first met at the sets of 'Saturday Night Live' in 2011. They began dating six months later and got engaged this January.

Wishes poured in for the couple and the 29-year-old 'Rush' star thanked her fans.

"WOW. You guys are awesome. So kind. Thank you thank you thank you! PS. Babies eat mostly salsa right?" she tweeted.

Earlier this year, Olivia expressed her desire of having children.

"I'm open-minded about how many, but three, which I love, is like a little party. I am not trying to have kids now - there's no strict plan for anything in my life. What happens, happens. He's (Jason) so good with kids ... I've never before experienced looking at someone and thinking, 'That's who I want to raise a child with,'" she said in an interview with Marie Claire.

The couple oozes chemistry. Jason, who has become much leaner lately, credited Olivia for his fitness. The 38-year-old said he is enjoying a great sex life with his fiancé.

"The truth is, I'm not getting up an hour earlier and walking on a treadmill. I have the greatest workout partner in the world. And you don't need a gym membership for that kind of workout," he told Elle magazine. He was earlier married to actress Kay Cannon. The couple ended their marriage six years later.

In 2003, when she was 19, Olivia married Italian filmmaker and musician, Tao Ruspoli in extreme secrecy. They married in an abandoned school bus with only a couple of witnesses. She later stated that they wanted to be alone because they wanted to keep the marriage a secret. Almost seven years later, the couple announced their separation and Olivia filed for divorce March 2011 citing "irreconcilable differences." The divorce was finalized September 2011. The couple reached a private agreement on property division as she did not seek any further support from Tao.