A pair of conjoined twins were successfully separated during a complex procedure that marked a surgical first for the Fort Worth, Texas, pediatric hospital where it took place on Monday. 

The infants, AmieLynn Rose and JamieLynn Rae Finley, “are recovering well,” officials at the hospital, Cook Children’s Medical Center, wrote in a news release describing what they called a “historic surgery.” AmieLynn and JamieLynn were born prematurely to parents and Fort Worth residents Amanda Arciniega and James Finley, at the nearby Texas Health Harris Methodist Hospital on Oct. 3. 

At the time of their birth, the twins were joined along their abdomens and shared skin, muscle and intra-abdominal organs, including a liver, according to Cook Children’s Medical Center. A 2016 report published by the National Institutes of Health suggests that omphalopagus twins — the technical term means that part of the gastrointestinal system and abdominal wall is shared– have the best chances of survival following a successful separation. About 10% of babies born conjoined are omphalopagus twins, according to the agency.

AmieLynn and JamieLynn’s separation surgery involved a team of 25 medical professionals, including six surgeons, who performed the delicate operation over the course of 11 hours. The team was divided and assigned to focus on either AmieLynn or JamieLynn’s individual surgeries once the separation procedure was complete, the hospital said.

“This is a historic, amazing day,” said Wini King, senior vice president and chief of communications, diversity, equity and inclusion for the Cook Children’s Health Care System, at a news conference held on Wednesday.

“This is a magical moment for Cook Children’s,” echoed Rick Merrill, the president and CEO of the hospital, in his own remarks at the conference. 

Prior to undergoing surgery this week, AmieLynn and JamieLynn had already defied a number of odds. Their condition at birth is rare, and although health officials believe the incidence of conjoined twins is underreported globally, current statistics indicate that this occurs in about one of every 50,000 to 200,000 births. Of conjoined twins who survive birth, about 25% live long enough to be eligible for separation surgery, according to the NIH.

“We are very happy with their progress at this point,” said Dr. José Iglesias, the lead surgeon on the Finley twins’ case. “We are focusing on their healing. They obviously have risks for several things but we’re keeping an eye on those.”

“They’re going to grow up into the little girls that they’re supposed to be: independent and feisty, like they’ve already shown us,” Iglesias added, drawing a burst of knowing laughter from the audience. “So, we’re very thankful with that so far.”