Australian scientists at the Victor Chang Institute have discovered miscarriages and birth defects can be prevented by simply taking a Vitamin B3 supplement.

A landmark Australian study has discovered Vitamin B3 can cure critical molecular deficiencies in pregnant women that cause miscarriages and birth defects.

The breakthrough made at Sydney's Victor Chang Cardia Research Institute may spare scores of couples across the world the heartbreak of losing an unborn child and the challenges of raising a baby with a birth defect.

"The ramifications are likely to be huge. This has the potential to significantly reduce the number of miscarriages and birth defects around the world, and I do not use those words lightly," lead researcher Professor Sally Dunwoodie said on Thursday.

Every year 7.9 million babies are born with a birth defect worldwide, while one in four Australian pregnant women suffers a miscarriage.

In most cases the cause of these problems has remained a mystery.

Using whole exome sequencing technology, researchers looked for gene variants in families that had experienced multiple congenital malformations.

Prof Dunwoodie and her team found that a deficiency in a vital molecule, known as NAD, cripples the growth of an embryo in the womb.

Nicotinamide adenine dinucleotide (NAD) is one of the most important molecules in all living cells. It's synthesis is essential for energy production, DNA repair and cell communication.

Environmental and genetic factors can disrupt its production.

After 12 years of research, Prof Dunwoodie revealed that a NAD deficiency can be cured by taking dietary supplement vitamin B3, also known as niacin.

Vitamin B3 is required to make NAD and is typically found in meats and green vegetables as well as Vegemite.

In the laboratory, scientists investigated the effect of vitamin B3 on developing mice embryos with the same genetic mutations as the study participants.

Before the vitamin was introduced into the mother's diet, embryos were either lost through miscarriage or the offspring were born with a range of severe birth defects.

After the dietary change, both the miscarriages and birth defects were completely prevented, with all the offspring born healthy.

The findings are published in the prestigious New England Journal of Medicine.

Victor Chang Cardiac Research Institute executive director Prof Robert Graham said the "profound" discovery is akin to the breakthrough made last century that confirmed folic acid supplementation can prevent spina bifida and other neural tube defects in babies.

"This will change the way pregnant women are cared for around the world," he said.

With research suggesting at least a third of pregnant women have low levels of vitamin B3 in the first trimester, Prof Dunwoodie says many pregnant women may require more B3 than is currently available in most vitamin supplements.

Researchers are now working on developing a diagnostic test to measure NAD levels to enable doctors to identify women at risk pregnant women.