The rates of spina bifida and other neural birth defects in Australian babies have declined since the introduction in 2009.

A review of the program has found the rate of neural-tube defects among teenagers has decreased by almost 55 per cent and by 74 per cent among Aboriginal women.

The review has found the overall rate of neural-tube defects has decreased by 14.4 per cent since its implementation.

Conducted by the government-funded Australian Institute of Health and Welfare, the review shows that reduction is in line with predictions.

The report's co-author, Ann Hunt, has told the ABC the results prove the once controversial program has successfully addressed an important health issue.

"The bread industry and people like that were concerned that they were being asked to (implement) public-health initiatives. At the time, there was a lot of controversy, but now it's well-accepted. And it's been very well implemented into the food system."

What was not expected from the review was the even bigger decrease of neural-tube defects among babies born to teenagers and Aboriginal and Torres Strait Islander women.

The rate of neural-tube defects among teenagers decreased by almost 55 per cent, and by 74 per cent among Aboriginal women.

The Apunimpa Cape York Health Council's Dr Mark Wenitong says he welcomes the findings.

"Look, I think it's fantastic. This is about changing the system so that everybody gets access to these fortified foods, and to make such a difference as that, it's a very, very successful program. It's fantastic that it's the young women as well that are having the increases, because, in our population, a lot of our pregnant mums are young, much younger than the rest of the population. And, often, they miss out on some of the nutritional factors during their pregnancy -- well, before their pregnancy, as well. So this is really good information. It kind of shows as well, I think, that, likely, people are getting better access to some of these foods as well that are fortified, which is also an access problem just around normal nutrition. So getting both, access to decent nutrition and fortified foods such as breads and cereals, is a really positive thing for our women and our babies."

Ms Hunt says the significant decrease is a great result after previous strategies were disproportionate.

"There'd been various strategies before this to try and increase folic-acid intake in women, and, while there'd there been some successes, it was quite uneven, and different socio-economic groups and ethnic groups appeared to be missing out, so this seems to be a very positive outcome for all Australians."

Folic acid is a B-group vitamin that helps prevent neural-tube defects like spina bifida in infants.

A neural-tube defect is an abnormality of the brain and spinal cord which occurs very early in pregnancy.

The risk is reduced if the expectant mother has sufficient folate levels.

The report says the fortification of bread has also remedied the re-emergence of mild iodine deficiency in the general population.

Ms Hunt says iodine is vital for the development and functioning of the thyroid gland, especially in infants and young children.

"Iodine intakes had decreased, and that's really important, having enough iodine, especially for the developing brain. So, children up to two years, it's really important they have enough iodine. And iodine is neccessary for the thyroid, the formation of thyroid hormones and the thyroid, and, if you have insufficient iodine, it can cause all sorts of problems with the thyroid. This requirement required the ordinary salt in bread to be replaced by iodised salt, and this was a very effective way of increasing iodine intakes in the Australian population."

Mandatory fortification of bread with folic acid and iodine was introduced in Australia in 2009 under the Australia New Zealand Food Standards Code.