Australian doctors have discovered a cheap and simple solution to a deadly health problem suffered by very premature babies.

One in eight babies born in Australia are born premature, and many babies born eight weeks early can develop a serious bowel condition called necrotising enterocolitis, or NEC.

The potentially fatal condition, which occurs because the baby's gut is colonised by bad bacteria instead of good bacteria, can require surgery and multiple hospital visits.

Babies with the illness can also have neurological complications such as cerebral palsy.

Dr Girish Deshpande from Sydney's Nepean Hospital says there are not many effective treatments for the condition, so prevention is the best option.

Because of this, doctors at the hospital have been trialling a probiotic supplement on all babies born eight weeks premature.

It is live, friendly bacteria, similar to that found in some yoghurts.

In this case, doctors sourced the purest probiotic they could find, finding the best one from Switzerland.

It is mixed with breast milk and given to the babies through a feeding tube.

Dr Deshpande says there is good evidence to show that probiotics improve gut integrity.

"They also reduce the inflammation in the gut as well, so it's very well documented and that's why we chose probiotics for little pre-term babies here," he said.

"Probiotics are quite helpful in preventing this serious and deadly condition."

Fourteen-month-old Madison Parsey was the first Australian baby to have the probiotic.

Her dad Scott says it was an easy decision to take part in the study.

"We came to the conclusion that the benefits far outweighed any negatives," he said.

"She hasn't taken a backward step since.

"She tolerated the treatment well. She is now healthy and not showing any signs of health problems."

An early trial showed the treatment reduced the incidence of bowel disease by 50 per cent.

And when probiotics were given to all the premature babies in the nursery, the effect was even greater.

In the last year, no babies given the probiotic at Nepean Hospital have developed the bowel condition.

All very premature babies at hospitals like Nepean now get the supplement as a matter of course.

Doctors say another advantage of the treatment is the cost.

It can cost around $250,000 to treat a child who gets the disease, while a course of the probiotic is as little as $75.

Ezekiel Huxley was born at 28 weeks in November last year.

He has just left Nepean's neonatal intensive care unit after treatment, including getting the probiotic.

His father Stephen says having the supplement was comforting.

"I think for us, it gave us a real peace of mind knowing that there was just one less thing we had to worry about," he said.

With the success of the probiotic supplement, the treatment is being rolled out to hospitals in Australia and New Zealand.