20/01/2010 14:24 GMT | Updated 22/05/2015 10:12 BST

N: What Are Neural Tube Defects?

Concerned mother with doctor Neural tube defects (NTDs) occur during early pregnancy and can cause both mental and physical problems in the baby.

During development, the neural tube eventually forms the spinal cord and brain of the baby. At the beginning of pregnancy, this tube is open but should close by the end of the first month of gestation.

When the tube fails to close properly, the backbone, spinal cord and brain are at risk and serious defects can occur.

The three main categories of neural tube defects are:

Spina bifida - where the tube does not close properly around the spinal cord, sometimes leading to serious neurological problems.

Encephalocele - a severe defect caused by incomplete development of the skull allowing the brain to protrude through the hole

Anencephaly – an extremely serious defect that is the result of underdevelopment of the brain and the skull.

These defects are often diagnosed via routine tests while an amniocentesis (which measures alpha-feto-protein, present in increased amounts if an NTD has occurred) can confirm any neural tube defects.

Factors that may contribute to the development of NTDs include poor nutrition, exposure to chemicals or radiation and occasionally due to genetic predisposition.

However, one of the most common causes is a lack of folic acid both before and during the early stages of pregnancy.

The good news is that up to 70 per cent of cases can be prevented by taking folic acid supplements before becoming pregnant and during the first few weeks of pregnancy.

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