A London hospital said Faith Williams, who survived a high-risk operation Tuesday to separate her from conjoined twin Hope, is now “very sick,” Agence France-Presse reported Thursday.

“Faith Williams is a very sick little girl,” said a statement from Great Ormond Street Hospital. “(The hospital) is doing everything it can for her, and we continue to offer her the highest possible levels of care.”

Hope died shortly after the 11-hour procedure, where the twins were separated from their breastbone to the top of the naval. They shared blood circulation, intestines and a liver, but had their own organs.

Faith was in stable condition Wednesday, and doctors gave her a 50 percent survival rate.

The girls were born via Caesarean section on Nov. 26.

Faith’s mother, Laura, 18, is Britain’s youngest mother to ever give birth to conjoined twins.

Doctors had hoped to wait until the twins were older to separate them, but the girls’ health had started to fail.

Click here to read more from the AFP.