“We waited so long that we decided to double up!" the couple tell PEOPLE exclusively

By Karen Mizoguchi and Aili Nahas
December 12, 2017 06:00 PM

“We waited so long that we decided to double up!” the couple tell PEOPLE exclusively. “We are very grateful for the blessing of twins.”

The Dancing with the Stars pro, 41, confirmed her pregnancy on Instagram on Monday with a too-cute sonogram featuring one of her unborn children flashing a thumbs-up hand gesture.

While Kym is experiencing pregnancy for the first time, her husband Robert Herjavec, 55, is already a father to three children from a previous marriage.

Jason LaVeris/Getty

The parents-to-be and former DWTS partners fell in love during show rehearsals of the 20th season in 2015, and continued to date after they were eliminated in week 8 at sixth place. Kym and Robert wed in summer 2016, saying their “I dos” in front of family and friends (including DWTS alums Joey Fatone, Lance Bass and Donny Osmond) in Los Angeles.

RELATED VIDEO: Kym Johnson Posts Adorable Photo of Her Pooch Lola Preparing for Her Twins’ Arrival

This year, the couple celebrated their first wedding anniversary, telling PEOPLE in August, “One year down, and many more to go! It was beautiful. We had a beautiful dinner. We still love to dance, so we had a dance. It was very romantic.”

Adding, “It feels like we’ve known each other forever. It’s been almost three years since we met. He’s just amazing. We’re best friends, and it’s just easy.”