Country star Thomas Rhett and his wife Lauren Akins are celebrating America's Mother's Day as parents-to-be.

The couple is set to welcome its fourth child - and fourth daughter - later this year.

The Die a Happy Man singer shared the news with fans on social media in the early hours of Sunday, after performing a show in Texas on Saturday night.

Alongside a photo of the smiling pair, with Lauren's baby bump on full display, Thomas wrote, "Well... we are pregnant again!"

"Tonight when I was on stage in Fort Worth about to play 'to the guys that date my girls' my wife talked to me in my (ear monitors) and said 'you can tell them if you want' so anyways, now you know. We are pumped to be having our 4th girl (sic)."

He then joked about the cost of raising a big family, adding, "Feel free to buy all the merch you want, knowing that all the proceeds are going straight to all these weddings I'll be paying for one day! Love you so much @laur_akins we always wanted a big thanksgiving table (sic)."

Thomas and Lauren, who wed in 2012, are already parents to biological daughters Lennon, 14 months, and three-year-old Ada, who was born shortly after the couple adopted now-five-year-old Willa from Uganda.

The country musician was soon flooded with congratulatory messages, with pal Maren Morris writing, "It's gonna be Pride & Prejudice up in that house! Congratulations, y'all (sic)!"

"Congrats you guys!!!!" added Dan + Shay star Shay Mooney, as Little Big Town's Karen Fairchild commented, "Congrats y'all (sic)!!!!"