"Josh & Me & BABY makes three!!! #mylovelybabybump," Fergie tweeted Monday, along with a photo of herself and Duhamel as children.
Earlier this month she sparked pregnancy rumors after being photographed in loose-fitting clothing and coats. However, in September, Fergie denied rumors she was pregnant when fluctuating weight had her wearing looser clothing.
Fergie and Duhamel married in January 2009 and discussed their desire to have children on an October 12 episode of Oprah’s Next Chapter. Duhamel hoped to have five children one day, but Fergie disagreed.
“We negotiated that early on,” she said. “Two is our number.”
While Duhamel, 40, stayed mum when we asked him about baby bump rumors at his recent Safe Haven premiere in Los Angeles, the thesp did say having a child would be his "greatest life achievement."
He also announced the news on his Facebook page, writing "Fergie and Me and BABY makes three. #MyLovelyBabyBump," along with the same photo.
Fergie joined several other stars due this year, included Jessica Simpson, Kim Kardashian and the Dutchess of Cambridge, Kate Middleton.