Causes of spina bifida 

The cause of spina bifida is unknown, although a number of things that can increase the risk of the condition have been identified.

Lack of folic acid

Not having enough folic acid during pregnancy is one of the most important factors that can increase your chances of having a child with spina bifida.

Folic acid is a vitamin that occurs naturally in some foods, such as broccoli, peas and brown rice. It is also added to foods, such as some breakfast cereals and folic acid tablets that are available from pharmacies, supermarkets and health stores.

It's estimated that taking folic acid supplements before you conceive and while you are pregnant may prevent up to seven out of 10 cases of neural tube defects, such as spina bifida.

Exactly how folic acid helps to prevent spina bifida is still uncertain. It may affect how the cells and tissue form in the developing baby.

Read preventing spina bifida for more information and advice about folic acid and folic acid supplements.

Family history

Having a family member with a neural tube defect, such as spina bifida, increases your chances of having a baby with spina bifida.

If you have previously had a child with spina bifida, your risk of having other children with the condition is significantly increased – from less than 1 in 1,500 to around 1 in 25.

If you have a family history of spina bifida, it’s very important that you take high-dose folic acid, prescribed by your GP before you become pregnant, and for at least the first 13 weeks of pregnancy.


Taking certain medications during pregnancy has been linked to an increased risk of spina bifida and other birth defects.

Two medications particularly linked to spina bifida are valproate and carbamazepine. These are most widely used to treat epilepsy, but are also used to treat some mental health conditions, such as bipolar disorder.

Doctors will try to avoid prescribing these medications if there is a chance you could get pregnant while taking them, but they may be needed if the alternatives aren’t effective.

It's advisable to use a reliable form of contraception if you need to take one of these medications and aren't planning a pregnancy.

Tell your doctor if you are thinking about trying for a baby and you need to take one of these medications. They may be able to lower the dose of your medication and prescribe folic acid supplements at a higher than normal dose, to help reduce the risk of problems.

If you're not sure whether a certain medication could affect your pregnancy, check with your doctor, midwife or pharmacist before taking it.

You should never stop taking a prescribed medication unless advised to do so by your GP or another qualified healthcare professional responsible for your care.

Genetic conditions

Some cases of spina bifida occur as part of a genetic condition affecting the chromosomes (bundles of genetic material found in cells).

Each cell in the body normally contains 23 pairs of chromosomes, but occasionally something goes wrong and a baby ends up with three versions of a particular chromosome.

These conditions include Patau syndrome, Edwards' syndrome and Down's syndrome.

Additional tests such as amniocentesis (where a sample of amniotic fluid is removed and tested) may be carried out during pregnancy if your baby is found to have spina bifida and it's thought it may have occurred alongside one of these conditions.


Women who are obese are more likely to have a child with spina bifida than those of an average weight.

Being obese means you have a body mass index (BMI) of 30 or more. You can use the healthy weight calculator to work out your BMI.


Women with diabetes may have an increased risk of giving birth to a child with spina bifida. This might be due to the excess glucose in the blood interfering with the child’s development.

Page last reviewed: 26/02/2015

Next review due: 26/02/2017