The 11-hour operation to separate the twins, who were joined from the breastbone to the top of their navels, was carried out in the British capital's Great Ormond Street Hospital. The girls shared a liver but had separate hearts.
Doctors were forced to carry out emergency separation surgery on the week-old babies after the twins' health rapidly deteriorated due to a blockage in their joint intestine.
Baby Hope died as she was unable to breathe, while her sister Faith survived the operation and is currently in a stable condition, although she will need further surgery to close her stomach. She is now in intensive care.
"The technical separation worked well and went according to plan," the doctor said. "However, shortly after the operation it became apparent that Hope's lungs were too small to support her breathing. The lungs of Faith were somehow supporting Hope."
Doctors say every case of conjoined twins is different, and every operation is a unique experience in surgery and recovery therapy. Such cases are fraught with organ failures and other complications. Separation surgery is considered successful if at least one of the patients survives.
Conjoined twins usually occur in women aged 25 to 40 years, when a single egg, from which identical twins usually develop, fails to divide properly. This occurs in one of 400,000 births, and the survival rate is 5-25%.
The mother of Hope and Faith, 18-year-old Laura Williams, is the youngest known woman to give birth to conjoined twins.
