Childbirth experts have issued a warning about research that has found vitamins can prevent many miscarriages in pregnant women.
A study released this week by the Victor Chang Institute found taking vitamin B3 supplements can reduce miscarriages and birth defects.
Scientists from the Victor Chang Institute in Sydney investigated why some women have multiple miscarriages and why some babies are born with heart, kidney and spinal defects.
They found a major cause was a deficiency of a vital molecule known as NAD, which is important for normal development of organs.
In a study published in the New England Journal of Medicine, the team proved birth defects and miscarriages could be overcome by taking vitamin B3.
However the Royal Australian and New Zealand College of Obstetricians and Gynaecologists has warned the claims are potentially harmful.
"Until randomised controlled studies are done, it is premature to claim a medical breakthrough... excessive consumption of vitamin B3 may be harmful to both the woman and the baby," it said in a statement.
The college is warning human studies need to be conducted and that women should not overdose on the vitamin.
The Victor Chang Institute has responded to the criticism, saying further research was already underway.
"Under no circumstances do we want to offer false hope to families who have been affected by miscarriage or birth defects," a spokesperson for the institute said.
"However, our research provides strong evidence that vitamin B3 has the potential to prevent these terrible outcomes in some cases."
The Victor Chang Institute has encouraged women to follow the current recommended dose of vitamin B3 (18 milligrams per day) when preparing for pregnancy.