Scotland is considering whether to add folic acid to flour as concern mounts that there could be an increase in birth defects while the Westminster government delays a decision.
Any move by Scotland could lead to folic acid being added to flour-based products UK-wide, as this would be the easiest solution for commercial bakers.
Folic acid plays a crucial role in preventing neural tube defects such as spina bifida.
But 85% of women do not take enough.
Government advisers have recommended adding folic acid to flour for 16 years but the Department of Health says it is still "considering the matter".
In the meantime, some food manufacturers have reduced the amount of folic acid they add to other foods, such as cereals, in anticipation of the fortification of flour.
Experts say that this means children are at higher risk of birth defects.
The Scottish government says it would have preferred a UK-wide approach but has grown increasingly frustrated with the lack of progress.
It is particularly concerned as unplanned pregnancies are more common in deprived communities.
By James Gallagher, health editor BBC, News website
Why is the UK government seemingly dragging its feet over fortifying flour - something about 80 countries already do?
The government's advisors the Scientific Advisory Committee on Nutrition has repeatedly called for the mandatory fortification of flour.
However, there are concerns that fortifying flour would lead to some people getting too much folic acid as some foods, including spreads and breakfast cereals, are voluntarily fortified.
The advisory committee says this would need careful handling and this is one possible source of delay.
But there is growing concern that food manufacturers are already reducing the levels of fortification in anticipation of fortified flour becoming mandatory.
And concerns have been raised that inaction is leading to more cases of spinal defects.
There are also echoes of the debate around adding fluoride to water with concerns over the nanny state and forcing people to have fortified bread.
Although white flour is already fortified with iron, calcium and some vitamins.
The decision lies firmly with the Department of Health, which is only saying the matter is being considered.
Scotland's Public Health Minister Maureen Watt said: "The Scottish government has been convinced of the case for mandatory fortification for some time. Folate levels are a concern across the UK, but particularly so in Scotland and Northern Ireland.
"We are disappointed that, despite repeated lobbying from a number of sources, there has been no progress at UK level on mandatory fortification of flour with folic acid.
"I have recently written again to the UK government to press for a decision on this important issue.
"I, along with my counterparts in Wales and Northern Ireland, will consider how we might progress this should a decision not be forthcoming from the UK government."
BBC Scotland understands that, if Scotland decided to go ahead with fortification of flour, some bread manufacturers would simply include folic acid in all their UK products rather than make products just for Scotland.
The Food and Drink Federation said: "From a practical point of view, manufacturers would favour a harmonised situation across the UK rather than Scotland 'going it alone' on mandatory folic acid fortification.
"Precise implications of such a situation are not yet clear due to ongoing UK government consultation on the Bread and Flour Regulations.
"If mandatory folic acid fortification is introduced, voluntary practices should be allowed to continue, and FDF members will work with the government to ensure this is done responsibly to prevent the risk of overconsumption."
The federation said it was not aware of any widespread reduction in the amount of voluntary folic acid currently added to products.
However, in October the chair of the UK's Scientific Advisory Committee on Nutrition (SACN) wrote to all UK health ministers pointing out that adding folic acid to flour had no adverse health effects in other countries, and led to a significant fall in birth defects.
The chair of the committee warned of the unexpected consequences of delaying a decision: "Some sectors of the food industry have already reduced the amounts of folic acid in their products in partial compliance with SACN's recommendations.
"This unforeseen conjunction of reduced voluntary fortification in the absence of mandatory fortification may unintentionally have reduced folic acid intakes and worsened the folate status of the population."
A spokeswoman for Food Standards Scotland said: "Food Standards Scotland work with the Scottish government on folic acid and entirely agree with their position."
Spina Bifida Hydrocephalus Scotland (SBH Scotland) welcomed the latest development.
Chief executive Andy Wynd said: "In Scotland it is thought that nearly 50% of pregnancies are unplanned and mothers-to-be will not have increased folic acid intake prior to conception.
"SBH Scotland believe that mandatory fortification will make a significant difference to the many planned and unplanned pregnancies diagnosed with Neural Tube Defects, of which spina bifida is the most common."
Adding folic acid to flour was first recommended by the UK's Committee on Medical Aspects of Food and Nutrition Policy (Coma) in 2000. It was also recommended by the SACN in 2006 and 2009.
Folic acid is found naturally in dark green leafy vegetables and other foods.
Last December, a study suggested birth defects in 2000 babies could have been avoided if the UK had fortified flour in 1998 at the same time as the US. A total of 77 countries around the world currently fortify flour with folic acid.
The current UK advice to women is to take folic acid supplements while trying to get pregnant. However, research suggests that only one third of women take them at the right time.
Supplements should begin three months prior to conception and continue during pregnancy.