The government is consulting on plans
Pregnant women are already advised to take folic acid, but many do not.
It is estimated fortifying flour with folic acid could prevent up to 200 birth defects a year.
The charity Shine, which has campaigned for the move for 25 years, said it hoped it would not be another 25 before it happened.
- Will folic acid ever be added to UK flour?
Women are advised to take 400 micrograms of folic acid a day for at least a month before conception and up to the 12th week of pregnancy.
But about half of pregnancies are unplanned, and women are not always aware they should take the supplement – or forget to.
Neural tube defects, such as spina bifida (abnormal development of the spine) and anencephaly, which affects the brain, affect about 1,000 pregnancies per year in the UK.
Over 40% of cases are fatal. Most babies who survive will need continuing care.
Mandatory fortification would mean everybody who ate foods such as bread would get more folic acid, but scientists have advised the government the recommended level is safe.
“Women from the poorest areas are less likely to take folic acid supplements and it is right that we do all we can to protect the most vulnerable in society,” Public Health Minister Seema Kennedy said.
“We all want to give our children the best start in life and a birth defect diagnosis is devastating for parents.
“The simple measure of adding folic acid to flour would help spare hundreds of families from such a life-changing event.”
Shine chief executive Kate Steele said: “Had it been introduced all those  years ago, when the government’s own scientific advisory committee on nutrition made the recommendation, it is estimated that it could have saved several thousands of UK pregnancies from being affected by spina bifida or anencephaly.
“However, we are not looking a gift horse in the mouth and are delighted that the government has launched this consultation and all we hope is that it will not take another 25 years to make mandatory fortification with folic acid a reality.”
More than 60 countries already add folic acid to flour. When Canada introduced mandatory fortification, in the late 1990s, neural tube defects halved. And when the same change was made in Australia, neural tube defects fell by 14%.
The UK-wide consultation will last for 12 weeks. UK milled wheat flour already has the vitamins thiamine and niacin as well as iron and calcium added.