The role of folic acid in pregnancy and pre-conception
By Annemarie Aburrow RD
By Annemarie Aburrow RD
Folic acid, also known as vitamin B9 or folate, is very important for pregnancy. In fact folic acid is the only vitamin recommended to be taken before you even start trying for a baby.
Folic acid is so important because it helps prevent neural tube defects (NTDs). The most common of these birth defects are spina bifida and anencephaly. The baby’s neural tube starts developing in week 3 of pregnancy – before you know you’re even pregnant, when specialised cells begin to fuse together to form a tube. This tiny tube eventually becomes the baby’s brain and spinal cord. A defect can occur if the tube doesn’t close properly, leaving an opening of the brain or spinal cord. The formation of the neural tube is completed by week 12.
We use folic acid to make new cells, including those specialised cells of the neural tube. Folic acid is also needed to make the chemicals which enable messages to be sent between nerves in the brain and spinal cord, e.g. serotonin. Research suggests that the developing baby has high requirements for folic acid, which cannot be met by diet alone. Research shows that taking folic acid supplementation before you fall pregnant can prevent at least 50% of NTDs. It is therefore very important that you start taking folic acid supplements before you start trying for a baby.
In the preconception stage, folic acid is the only vitamin that is recommended by the Department of Health. A dose of 400 micrograms every day is required. Start this before you start trying for a baby and continue taking until you are at least 12 weeks pregnant. Once you find out you’re expecting, vitamin D supplements are also recommended, although most women decide to take a pregnancy multivitamin and mineral tablet or Healthy Start Vitamins, which include both folic acid and vitamin D.
Some women have a higher risk of having a baby with NTDs, and are therefore advised to take a higher dose of 5 milligrams of folic acid during preconception and early pregnancy. You are at increased risk if you’ve had a previous pregnancy affected by a NTD, have diabetes, or if you or your partner have a NTD, or have a family history of NTDs. You may also need this higher dose if you take anti-epileptic medication. This 5mg dose of folic acid is not routinely stocked on the shelf, so ask your GP for further advice and to request a prescription.
In addition to taking folic acid supplements the Department of Health recommends a diet rich in folate. Folate is the natural form of folic acid found in food. Green leafy vegetables (e.g. spinach, kale, broccoli), brown rice and granary bread are good sources of folate. In addition, folic acid is added to many brands of breakfast cereals and spread/margarines. Check the label of your usual brand and consider switching if they don’t contain added folic acid.
If you’re trying for a baby, start taking folic acid supplements. As you may not know the exact day of conception, this ensures you are taking it right from the start of your pregnancy to give your baby the best chance of healthy neural tube development.
Great Britain Committee on Medical Aspects of Food and Nutrition Policy Working Group on the Nutritional Status of the Population Great Britain Department of Health (2000) Folic acid and the prevention of disease. Report of the Committee on Medical Aspects of Food and Nutrition Policy. London: The Stationery Office.
MRC Vitamin Study Research Group (1991) Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 338(8760):131-137.
NHS Choices. Vitamins and nutrition in pregnancy (Accessed 1st August 2013).