Formerly Conjoined Twins Celebrate First Birthday

— -- Formerly conjoined twins Knatalye Hope and Adeline Faith Mata celebrated their first birthday with a "Frozen"-themed party at the hospital.

A team at Texas Children's Hospital separated the girls on Feb. 17 in a 26-hour surgery. They are still in the pediatric intensive care unit and have each had a few surgeries since the separation, but their mother, Elysse Mata, decorated their room with snowflakes and balloons.

"It's been a year," Mata said, surrounded by presents as the hospital filmed her. "It went by so fast. I feel like just yesterday they were born."

Earlier in the week, Mata had a party for everyone at the hospital who helped her babies over the last year. She said she was sad to leave some of the doctors from before the separation, but she knows it's a positive thing.

"Now they're good and healthy and hopefully headed towards home," said Mata, 25, of Lubbock, Texas.

Mata was shocked to learn the twins were conjoined when she was pregnant with them, she told ABC News in July.

"I was speechless, it was so unexpected,” she said.

The girls were born on April 11, 2014 at Texas Children's Hospital. They shared a chest wall, diaphragm, intestines, lungs, lining of the heart and pelvis. Their middle names are Hope and Faith because you can't have one without the other, she said.

"Nightline" was at the hospital in February as 12 surgeons operated on the Mata twins, and Elysse, her husband and 20 family members camped out in the waiting room.