Background Information
Folic Acid
Folic acid (vitamin B9) is essential for DNA synthesis and cell division, making it critical during periods of rapid cell growth such as early pregnancy.
Importance in Pregnancy
Folic acid is required for normal neural tube development, which forms the brain and spinal cord.
Deficiency increases the risk of neural tube defects, including:
- Spina bifida
- Anencephaly
- Encephalocele
Overview of Pregnancy and Supplements
NICE recommends taking the Healthy Start vitamins (free supplements provided by the NHS to eligible pregnant women) that contain:
- Folic acid 400 micrograms
- Vitamin C 70mg
- Vitamin D 400 IU
Vitamin A supplementation is not recommended during pregnancy.
Pregnant women should avoid:
- Taking supplements containing vitamin A (retinol)
- Eating liver or liver products (as they contain high levels of vitamin A)
Excess vitamin A during pregnancy has potential teratogenic effects.
Folic Acid and Pregnancy
When To Start Taking
Advise ALL women who are planning pregnancy to start taking folic acid BEFORE conception (i.e. before attempting to get pregnant).
If the woman is already pregnant and is NOT taking folic acid → advise to start taking folic acid ASAP
Rationale for pre-conception folic acid
Folic acid should be started before conception to reduce the risk of neural tube defects
- The neural tube closes by ~4 weeks of gestation and this is often before pregnancy is recognised (many people do not realise they are pregnant immediately and may test days to weeks later)
- Starting folic acid only after a positive pregnancy test may be too late to prevent neural tube defects.
It is important to still take folic acid supplements even if food (including flour) is fortified with folic acid.
Duration
Folic acid should be taken from whenever started (ideally pre-conception) until 12 weeks of pregnancy
Dosage (IMPORTANT)
| Type | Folic acid dosage | Indications |
|---|---|---|
| Standard dose | 400 micrograms daily | Most women, if high-dose folic acid is NOT indicated |
| High-dose | 5 mg daily | Those at increased risk of having a baby with neural tube defect or other congenital malformation.
ANY of the following:
|
Overweight / obesity is no longer an indication to take high-dose folic acid.
NICE: Reassure anyone with a body mass index (BMI) of 25 kg/m2 or more who is planning to become pregnant or is in the first 12 weeks of pregnancy that they do not need to take more than 400 micrograms of folic acid a day, unless they have any of the factors listed in recommendation 1.1.5.
Important NOT to mix up doses of folic acid:
- Standard dose is 400 MICROGRAMS (mcg) – not milligrams (mg)!
- High-dose is 5 MILLIGRAMS (mg)
References
NICE guideline Maternal and child nutrition: nutrition and weight management in pregnancy, and nutrition in children up to 5 years
NICE CKS Pre-conception - advice and management