Having passed her original due date, February 19, Abi is now at home near Esher, Surrey, with her overjoyed parents Louise and David. Picture: YouTube.com

She was born four months early, a week before the legal cut-off time for abortions.

But as if that was not enough of a threat to her tiny life, Abi Peters was suffering from a ruptured intestine.

Yet against the odds, 1lb 5oz (about .5kg) Abi survived being born at 23 weeks into pregnancy and then having to undergo major abdominal surgery only six days later.

Described by her mother and father as "our little miracle", she became the youngest patient ever operated on at St George’s Hospital in Tooting, South London – and the youngest in the world to have survived this kind of major surgery.

Having passed her original due date, February 19, Abi is now at home near Esher, Surrey, with her overjoyed parents Louise and David.

Medical staff believed the operation on Abi, who was smaller than the hand of her surgeon Zahid Mukhtar, had a less than 10 percent chance of success.

They used specially adapted tiny surgical equipment to repair her intestine, which had ruptured in three places. Abi had suffered perforated necrotising enterocolitis, a condition found mostly in premature babies where intestinal tissue becomes damaged and begins to die.

Mrs Peters, 32, said: "They told us all the risks but didn’t say this was the world’s youngest baby ever operated on, otherwise it might have scared us too much.

"We agreed to the operation, despite the risks associated with it, as we knew she wouldn’t survive without it.

"After she’d gone into theatre, Dave and I sat in a room for what was probably the longest three hours of our lives.

"When the door opened and one of the surgeons came into the room, we just looked at his face and we knew she was okay – he was smiling.

"Our baby girl is a fighter. She stayed in intensive care for a while and overcame many more hurdles, but she kept fighting and we are so pleased with how she is doing today. She truly is our little miracle."

Peters and her 43-year-old husband, a director at engineering firm Aecom in London, already had daughter, Tara, two. Mrs Peters, an analyst at Investec, gave birth to Abi at St Peter’s Hospital in Chertsey in October after going into premature labour.

Peters said: "Once the neonatal team had intubated Abi, we were allowed a quick peek and a kiss before she was rushed off.

"It was incredibly scary and certainly not the birth we had been imagining. She just looked so tiny and couldn’t make any noise or open her eyes.

"It was hard to believe something that small could survive, but we knew the fact she was being whisked away meant there was a chance."

Abi was transferred to the neonatal unit at St George’s. Consultant paediatric surgeon Mr Mukhtar, who led the ten-strong team that performed the hour-long operation on her, said: "It is a unique case and we only chose to operate because her chances of survival without surgery were so small.

"The fact she survived the operation, and is now doing so well, is fantastic news.

"We will continue to monitor her closely, but all the signs suggest we should be optimistic about her long-term prognosis."

The couple do not know why their daughter, whose full first name is Abiageal, was born prematurely as both Mrs Peters’ pregnancies had progressed without problem.