Jo Dee Messina is PREGNANT!

Country singer Jo Dee Messina announced yesterday that she is pregnant--and in her third trimester!

Messina, 38, just celebrated her one-year anniversary with Chris Deffenbaugh, 28, last week.

"We knew we wanted to have kids, but we just said, 'Whenever it happens, it happens.' And it happened!" she says. "We were both surprised at first. It's such a lifestyle change. But then we're like, 'Wow, we're going to be parents!'" she told People Magazine last week.

Messina and Deffenbaugh are expecting a boy sometime in December.

Jo Dee Messina...an introduction.

Jo Dee Messina debuted in 1996 with the single, "Heads Carolina, Tails California." Her album was certified "Gold" by the RIAA. Her second album, “I'm Alright” produced five Top 10 Country hits between 1998 in 1999 and sold over a million copies in America.

Since her debut, six of her singles have peaked at #1 on the Billboard Country singles chart and five of her albums have received a certification by the RIAA or the CRIA.