The world's smallest baby has been sent home from hospital three months after her birth, with doctors hailing her survival as a miracle.

She would fit right into your hand

Paediatrician Margarita Psaraki

The baby girl - nicknamed 'Perla' by her medical team - weighed only 285 grams (under 10 ounces) at birth at the Careggi hospital in Florence, Italy.

Doctors said they believe her to be the smallest human on record to have survived so long.

Perla, born two months premature, spent three months in intensive care following her birth, suffering from breathing difficulties, anaemia, hypothyroidism, hypoglycaemia and jaundice, according to Italian media reports.

Now weighing two kilograms (4.4 pounds), doctors said she now has almost a 100% chance of leading a normal life, and that her parents can bring her up normally.

Unique situation

Previously the record was in Japan in the 1990s where a baby weighing only 300 grams (10.5 ounces) was born.

Premature babies can face health problems in later life

But Perla's life was in the balance even before she was born.

Doctors induced the birth after fears for her mother's health.

Her mother developed arteritis - an inflammation of the arteries that led doctors at one point to consider amputating her leg and prompted them to deliver the baby early.

And after the birth, they were unsure how to proceed, given the tiny size of the baby; premature babies who survive birth at 27 weeks or later still face the prospect of severe mental or physical problems later in life.

'Will to live'

Paediatrician Margarita Psaraki, part of Perla's medical team, told Italian television channel Canale 5 that doctors could not believe her size when she was born.

"I was afraid of holding her," she said.

"She was ten inches (25 centimetres) long, but that's when she was stretched out, normally babies curl up."

"She would fit right into your hand."

Doctors spent three months nursing Perla back to health, at one point even commissioning a medical technology supplier to make equipment small enough for them to use on her.

"She really had the will to live, she was strong and lively," Ms Psaraki said

"She was immediately lively, active. This helped us to help her."