Faith Williams, the month-old conjoined twin who survived a lengthy surgery to separate her from her sister, died on the afternoon of Christmas Day, London's Great Ormond Street Hospital said.
Her doctor, Agostino Pierro, said in a statement that while Faith's death was very sad, it was not unexpected.
"We were always clear that Faith was very sick," he said. "She required the full range of skills of our intensive care staff, and underwent a number of further procedures. However, she succumbed to the complexities of her condition."
Faith and Hope were born Nov. 26, joined from their chests to the lower part of their stomachs. They had separate hearts, but shared a liver and intestines.
On Dec. 2, the pair underwent an 11-hour surgery to separate them, an operation that doctors had hoped could wait until the girls became stronger. But the infants' deteriorating condition made it necessary for the surgical team to separate the twins.
Hope died hours after doctors completed the 11-hour operation.
"Hope's lungs were too small to support ... breathing and the circulation," Pierro said after the twins were separated. "The lungs of Faith were somehow supporting Hope."
He said then that Faith's chances of surviving were about 50 percent.
Faith then underwent two further surgeries, one to try and resolve a problem with her circulation and the second to close her chest.
The babies' mother is 18-year-old Laura Williams, who is Britain's youngest-ever mother to give birth to conjoined twins.
