The world’s most premature living baby, born the length of a ballpoint pen at 21 weeks and six days, is to be allowed home from a Florida hospital today.

When she was born on October 24, Amillia Taylor weighed just 280g (10oz) and measured 24cm (9.5 inches). Doctors did not expect her to survive.

No baby born at less than 23 weeks was known to have survived before, according to the University of Iowa, which keeps a record of the world’s tiniest babies.

Amillia has spent four months in a neonatal intensive care unit at Baptist Children’s Hospital in Miami, where she has been in an incubator since birth, receiving oxygen.

She has experienced respiratory problems, a very mild brain hemorrhage and some digestive trouble, but none of the health concerns are expected to pose long-term problems, her doctors said.

Her mother Sonja Taylor said: “It was hard to imagine she would get this far. But now she is beginning to look like a real baby.”

She said: “Even though she’s only 4lb (1.8kg) now, she’s plump to me.”

Doctors said the baby girl is now thriving at 4½lb (2kg) – and between 25 and 26 inches (64 and 66cm) long – and well enough to be cared for by her parents at home.

“She’s going to be in a normal crib, she’s going to have normal feedings, she’s taking all her feedings from a bottle,” said William Smalling, a neonatalist at the hospital.

He said caring for Amillia in the past month was like navigating uncharted waters. “We didn’t even know what a normal blood pressure is for a baby this small.”

The baby was delivered by caesarean section after attempts to delay a premature delivery failed. She was breathing without assistance at birth and even made several attempts to cry.

The American Association of Pediatrics says that babies born at less than 23 weeks of age and 400g in weight are not considered viable. The survival rate for a child born at 23 weeks and weighing a pound is just 30 per cent.

Dr Smalling said: “It may be that we need to reconsider our standard for viability in light of Amillia’s case.”

He said: “Over the years, the technology that we have available to save these premature babies has improved dramatically. Today, we can save babies that would have never survived 10 years ago.”

Amillia is the first child of Eddie and Sonja Taylor of Homestead, Florida. She was conceived by in vitro fertilization, which made it possible to pinpoint her exact time in the womb.

Dr Smalling said: “She’s truly a miracle baby.”

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