Carrie, Chris and Keith steal the show at the Country Music Awards

(Reuters) - Chris Stapleton was the big winner but Carrie Underwood and her unborn baby stole the limelight at the Country Music Association (CMA) awards on Wednesday.

A heavily pregnant Underwood, one of country music's biggest celebrities, chose the live televised show in Nashville to reveal for the first time that the second child she is expecting is a boy.

Underwood, who co-hosted the show with singer Brad Paisley, won female vocalist of the year for the fifth time and brought the house down with an emotional performance of her single about bringing people together, "Love Wins."

"Thank you God. I have been blessed with so much in my life," Underwood said.

Stapleton won three awards - male vocalist of the year, single and song of the year for "Broken Halos."

But in a surprise result, he lost the night's biggest prize - entertainer of the year - to Keith Urban, the former "American Idol" judge and husband of actress Nicole Kidman.

"I am shocked beyond shocked," a tearful Urban said. "I feel very grateful that I get to do what I do. God bless country music."

Garth Brooks opened the show with a minute of silence for the 12 people shot dead last week at a bar in Southern California that was popular for country line dancing. The gunman, a former U.S. Marine, died of an apparently self-inflicted gunshot.

"Tonight, let's celebrate their lives," Brooks said. "Let the music unite us with love in their enduring memory."

On a male-dominated night, Kacey Musgraves, 30, won her first big CMA prize, taking home album of the year for "Golden Hour." No women were among the five nominees this year for entertainer of the year.

"2018 has been a huge year for men in country music," quipped Paisley as he opened the three-hour show with Underwood.

"Finally!" Underwood retorted.

The oldest and youngest stars were among the most-talked about performers.

Veteran bluegrass musician Ricky Skaggs, 64, got an extended showcase, playing with Paisley and Urban, while Brooks, a country staple for 30 years, debuted an acoustic ballad, "Stronger Than Me," dedicated to his wife, Trisha Yearwood.

On the younger end, Kelsea Ballerini, 25, performed her defiant dance-pop ode to female empowerment, "Miss Me More."

Other winners on Wednesday included Old Dominion, Brothers Osborne, Thomas Rhett, and best new artist Luke Combs.

(Reporting by Jill Serjeant; editing by Darren Schuettler)