Folic acid is to be added to the most commonly consumed flours in the UK to help prevent spinal conditions in babies, the government has announced.

Doctors advise pregnant women to take folic acid supplements but, with about 50% of pregnancies in the UK being unplanned, many mothers-to-be may not be able to do this early enough.

The government said requiring flour millers to boost non-wholemeal wheat flour with folic acid will actively help avoid about 200 neural tube defects in babies each year – reducing the annual UK total by about 20%.

The neural tube forms the early part of the brain and spine within the first 12 weeks of gestation, usually before the mother knows she is pregnant, and neural tube defects can result in spinal conditions such as spina bifida or anencephaly.

Kate Steele, the chief executive of Shine, a charity that provides specialist support for people whose lives have been affected by spina bifida and hydrocephalus, said: “Mandatory fortification of flour with folic acid will improve public health for so many, now and in the future.

“In its simplest terms, the step will reduce the numbers of families who face the devastating news that their baby has anencephaly and will not survive. It will also prevent some babies being affected by spina bifida, which can result in complex physical impairments and poor health. This is truly a momentous day.”

Folic acid is the human-made version of the vitamin folate, also known as vitamin B9, which helps the body make healthy red blood cells.

The addition of folic acid to food has been a successful public health policy in a number of countries worldwide, including Australia, New Zealand and Canada, resulting in falls in neural tube defects.

Non-wholemeal flour is already an established vehicle for fortification in the UK, and the costs of fortification to industry are expected to be minimal, the UK government said.

Alex Waugh, director of UK Flour Millers, said: “Flour, whether white, brown or wholemeal, is an ingredient in many foodstuffs, and supplies a big proportion of our daily fibre and protein along with essential nutrients such as calcium, iron and B vitamins.

“If it is decided that folic acid should be added to flour for public health reasons, flour millers will do all they can to overcome any practical challenges to make it happen.”

Folic acid is already voluntarily added by food manufacturers to breakfast cereal, including to some gluten-free products, meaning people can usually get all they need from eating a balanced diet, but a higher intake is required in the first 12 weeks of pregnancy.

The NHS strongly recommends women who could become pregnant or are planning a pregnancy take a 400 micrograms folic acid tablet every day before pregnancy and until they are 12 weeks pregnant, and this advice will continue.

Wholemeal flour and gluten-free foods are not subject to mandatory fortification and these products are not in the initial scope of this policy.