A leading paediatrician says the Government's decision not to make putting folic in bread mandatory was a "missed opportunity".
Paediatric Society Doctor Andrew Marshall said making folic acid mandatory would prevent 10 to 20 birth defects, such as spina bifida, a year.
"If the benefits are obvious with a mandatory regime then I hope the government would reconsider this decision," said Marshall.
New Zealand Organisation for Rare Disorders Director John Forman was also critical of the government's decision.
"They had a major responsibility to fix a serious known and preventable harm, and they've completely dropped the ball."
In Australia, all bread has been fortified since 2009.
But Food Safety Minister Kate Wilkinson said her decision came down to consumer choice over science.
"You can have scientists arguing black and scientists arguing white," said Wilkinson.
"At the end of the day the consultation went out, the submissions were clearly in favour of voluntary, so people can make up their own mind whether they want folic acid in their bread or not.
But research suggests most women do not know enough to make an informed decision.
A survey commissioned by the Government found only half of women surveyed knew folic acid was needed during pregnancy.
The Government is promising an education campaign about folic acid and says it will work with bakers to boost fortification rates from 12.5% of all packaged loaves to half.