A mom's priceless reaction was captured on camera as she welcomed a son, whom she thought would be a baby girl.

The viral photo, taken by Lauren Jolly Photography, made its rounds on birthing accounts showing Nancy Ray and her husband, Will Ray, the moment they learned that their third child was a boy.

"I was saying how beautiful she was and how much I loved her," Nancy Ray recalled of the moment her child was born. "Then we turned him over to cut the cord and I was like, 'What is that?'"

Nancy Ray of Raleigh, North Carolina, told "Good Morning America" that a sonogram technician placed the sex of her baby in an envelope during her 18-week anatomy scan.

Ray and her husband, who were already parents to two girls, went out to dinner to open the envelope together.

PHOTO: Nancy Ray, a mom of three, welcomed a son via midwife at a birth center in North Carolina on Dec. 13, 2018.
Courtesy Lauren Jolly Photography
Nancy Ray, a mom of three, welcomed a son via midwife at a birth center in North Carolina on Dec. 13, 2018.

"We just busted out laughing and we couldn't believe we were having three girls," Nancy Ray said. "That was it. We prepared for our third girl and we had a name picked out, got the nursery ready and had the surprise of our lives."

On Dec. 13, 2018, the Rays welcomed Beaufort Ray, who weighed 8 pounds, 5 ounces.

PHOTO: Nancy Ray of Raleigh, N.C., said doctors told her she was expecting a girl, but on Dec. 13, 2018, she welcomed a boy.
Courtesy Lauren Jolly Photography
Nancy Ray of Raleigh, N.C., said doctors told her she was expecting a girl, but on Dec. 13, 2018, she welcomed a boy.

And although it wasn't captured on film to such spectacular effect, dad Will was apparently just as surprised.

"My husband lifted his leg to check and sure enough, it was a boy, and he proceeded to fall on the floor -- he just could not believe it. " Ray said.

Photographer Lauren Holly said she was also shocked by the big moment.

"We all just freaked out and I'm thankful that I was able to continue to keep shooting," Jolly told "GMA."

Ray said she's not upset about the mistake, but happy it was caught in a photo.

"He's going to hear this story for the rest of his life," Ray said of her son.