Conjoined twins from Nigeria separated at Tennessee hospital .

Conjoined twin girls from Nigeria have been separated after a lengthy operation at a Tennessee hospital, days ahead of their first birthday. Miracle and Testimony Ayeni were separated during 18 hours of surgery that began on Nov. 7 and finished Nov. 8 at Le Bonheur Children's Hospital in Memphis, the hospital said. The twins were joined together at the pelvis, a condition that only occurs in one of about every 5 million births, said Dr. Max Langham, who led the surgical team. "Without separation, their future wasn't very good," Langham said at a news conference Tuesday. "They would grow up incontinent, unable to walk, totally dependent for all of their care and unable to participate in the world fully." Doctors are optimistic about the long-term prognosis and hospital spokeswoman Anne Glanker told The Associated Press that both girls are "doing really well." The twins have been in the hospital since their parents brought them from Nigeria in June to prepare for the procedure. The twins face additional surgeries and rehabilitation and it's not clear when they might return home. The family has another reason to celebrate — Wednesday is the first birthday of the twins. This is the second time a set of conjoined twins have been separated at Le Bonheur. Twin boys who were joined at the back and pelvis were separated in 2011. more