Country music duo Thompson Square now have a plus-one.

Husband and wife band members Shawna and Keifer Thompson welcomed their first child together, a baby boy they named Rigney Cooper Thompson, on Sunday January 24, E! News reports.

shawna and keifer thompson of thompson square 2015 getty

Shawna and Keifer Thompson in November.

The couple took to Instagram Sunday evening to share the news, along with an adorable photo snapped moments after their son's birth.

"We're so excited to be able to share this monumental day with all of you," the couple wrote. "We've had many wonderful things happen to us, but this absolutely tops them all. … Please say hello and welcome [to] this big ol world, Rigney Cooper Thompson."

Shawna, 37, gave birth to Rigney at 3:46 a.m. Sunday, according to E!.

"God blessed us this morning with a little 7 pound 13 oz miracle," the couple said in a statement to E!. "It's hard to explain this kind of love. We're so overjoyed. He's already got us wrapped around his little finger."

Shawna and Keifer, 39, got married in 1999 and announced her pregnancy on social media in September. Rigney is the maiden name of Shawna's grandmother, according to E!.

thompson square getty 2014

Shawna and Keifer Thompson.

RELATED: Country Duo Thompson Square Reveal the Gender of Their Baby!

Congratulations to the happy new parents!