When Adelaide mother Jo Slade gave birth to her son Ari, she wasn't sure whether he would survive.

"He came at 30 weeks … and he was in the intensive care unit for 10 weeks," she said.

"I always assumed that having a pre-term baby was just a small baby, but you don't understand the complications of what that means until you face the daily challenges of wondering: 'Are we going to make it through the day?'"

Ari is now eight years old and mostly healthy and strong, but he does have issues with his vision and a heart condition.

Now Adelaide researchers have now confirmed a "simple and cost-effective" way to help prevent premature births and their associated health complications.

Ari McEachean was born prematurely, at 30 weeks, and spent 10 weeks in intensive care. ( Supplied: South Australian Health and Medical Research Institute )

Researchers from the University of Adelaide, SA Health and Medical Research Institute (SAHMRI) and Women's and Children's Hospital reviewed the results of 70 studies from around the world, involving 20,000 women.

SAHMRI researcher Maria Makrides said the data showed daily omega-3 supplementation reduced the risk of birth before 37 weeks by 11 per cent, and reduced the risk of birth before 34 weeks by 42 per cent.

"These findings are very significant and important because there are very few interventions that can safely reduce the risk of prematurity," Professor Makrides said.

"The take-home message for expectant mothers who are carrying a single baby is to take a supplement with omega-3 fatty acids from the 12th week of pregnancy.

"The supplement should include at least 500 milligrams of the omega-3 fatty-acid called DHA."

Professor Makrides said while the outcome of the research was definitive, researchers were not entirely sure why omega-3 reduced the risk of early labour.

"We don't exactly know the mechanism by how omega-3 works but it is likely that it dampens down the potency of very powerful hormones … that often initiate premature birth … in order to extend the duration of gestation," she said.

Hopes research could lead to thousands of healthier babies

Women's and Children's Hospital neonatologist Andy McPhee said the results from the research review were "extraordinary".

Women's and Children's Hospital neonatologist Andy McPhee and SAHMRI researcher Maria Makrides. ( ABC News: Isabel Dayman )

"It's those babies less than 34 weeks where we're seeing the biggest benefit and they're the babies that are most at risk," Dr McPhee said.

"At extreme prematurity, at 23 or 24 weeks, there's a significant likelihood that the baby won't survive [or] that baby may survive, but with damaged organ systems.

"The extraordinary thing about this data is that in South Australia we probably have 500 to 600 babies under 34 weeks a year, and I calculate that we'll see 150 less of those because we're moving them into a more favourable gestational period.

"So that's a big deal … and around Australia that's going to translate to 1,000 or 2,000 babies, and around the world that's hundreds of thousands."

Ms Slade said it was "just so nice to know" there was a simple strategy for women to reduce their risk of pre-term birth.

"There's no risk with the supplement and there are no complications — it's a dose that if you exceed it, it just passes through your body," she said.

"I really support being involved with this type of messaging for people because it is something that can have a really lasting effect for the health of your child."

Health Minister Stephen Wade said the State Government planned to immediately roll out information about the research to expectant mothers and their doctors.