Folic acid is the man-made form of folate, a B-group vitamin found in foods such as leafy green vegetables.
Everybody needs folate for healthy growth and development. Your body uses it to make DNA and to help your cells divide and grow. It is particularly important for your blood cells.
Folate is also essential in early pregnancy – the embryo needs folate for normal development of the neural tube.
What is the neural tube?
The neural tube is one of the earliest parts of your baby to develop. It forms in the first four to six weeks of pregnancy. This is before most women even realise they are pregnant.
The neural tube will eventually become your baby’s brain and spinal cord, so it’s a critically important structure.
What are neural tube defects?
Neural tube defects (NTD) occur when the neural tube doesn’t close properly. This means the baby’s brain and spinal cord don’t develop properly. In Australia, NTD affects around 4-5 out of every 10,000 births.
There are quite a few different types of NTD. The two most common ones we encounter are spina bifida and anencephaly.
In spina bifida, the spine and its membranes fail to fully close around the spinal cord. The most common place for this gap in the spine is on the baby’s lower back. There is a spectrum of severity, from mild forms with no associated nerve problems, through to severe forms that cause problems with continence and walking.
Anencephaly is a very severe NTD. Large parts of the brain and skull fail to develop. There is no treatment or cure. Virtually all babies with anencephaly die before birth or within hours of being delivered.
Folic acid helps prevent neural tube defects
A lack of folic acid is not the only cause of neural tube defects, but it is an important risk factor. Up to 70% of neural tube defects can be prevented by having a high folate intake.
How much folic acid should I take?
Most women need a supplement containing 400 micrograms of folic acid per day.
Some women are at higher risk of having a baby with a NTD. These women should take a higher dose of folic acid – 5 milligrams per day.
You are at higher risk of NTD if:
- You have spina bifida yourself
- You have had a previous pregnancy affected by NTD, or there is a family history of NTD
- You have diabetes
- You have a condition that stops you absorbing nutrients, for example some bowel diseases
- You take certain medications, for example anti-epileptic drugs
- You are obese
- You are a smoker
This is not a complete list, so please check your individual requirement with your doctor.
When should I start taking folic acid?
Ideally, start your folic acid supplement 3 months before you start trying to conceive.
If you are already pregnant, start your folic acid as soon as you receive the positive pregnancy test.
Continue the folic acid supplement until you have passed at least 12 weeks of pregnancy.
How are neural tube defects diagnosed?
These days, the majority of severe neural tube defects are diagnosed during pregnancy, at the time of the 19-week ultrasound.
Spina bifida occulta will not be seen on prenatal ultrasound. It is often diagnosed after the baby is born, when the paediatrician notices a dimple or patch of hair on the baby’s lower back. Sometimes it isn’t diagnosed until later in life, when an X-ray or scan is done for other reasons.