Fritzl kept his daughter Elisabeth locked up in a secret, windowless cellar in the basement of his house, where she gave birth to seven of his children. Three of the children were kept locked in the cellar with their mother.
"The patient Kerstin F. was brought around from her artificial coma and was able to leave the intensive care unit a few days back," the hospital in Amstetten said. "The patient is still in need of intensive medical and therapeutic care."
Doctors put her into an artificial coma after she suffered from cramping fits due to oxygen deficiency and kidney problems and was brought from the prison cellar to hospital by Fritzl.
Three of the six surviving children of the incestuous relationship, now aged between 19 and 5 years, were locked up with their mother in the basement of the family's home in the town of Amstetten in the province of Lower Austria.
Another three were raised by Fritzl and his wife Rosemarie as their own, and one died shortly after birth.
Prosecutors are investigating the 73-year-old for coercion, rape, incest and the death of the baby, though he has not been charged. Police say he has admitted incarceration and incest.
The case unravelled after Kerstin, who had been locked up with her mother since birth, fell seriously ill and was brought to the hospital by Fritzl.
Austrian media reported that Kerstin might have been reunited with her mother, her grandmother and her siblings who are all cared for at the hospital.
A spokesman for the hospital could not immediately confirm this or provide any further details.
