Folic Acid and Folate Before and During Pregnancy: Neural Tube Defects and Official Advice
What official bodies in the US, UK and Canada advise about folic acid before and during pregnancy, what trials found on neural tube defects, and who is told to ask about higher amounts.
Content last updated . This page has not been medically reviewed.
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Talk to a midwife, doctor or pharmacist before you try to conceive, or as soon as you think you may be pregnant. Official advice on folic acid is aimed at people who are planning a pregnancy or could become pregnant, because the neural tube (the early brain and spine) forms in the first weeks. This page reports what each body says, with its country and date. It is not personal dosing advice, and it does not tell anyone to stop a medicine.What neural tube defects are
The NHS describes a neural tube defect as a problem with the brain or spine, or both, such as spina bifida. [1] The US Preventive Services Task Force (USPSTF) says neural tube defects are among the most common congenital malformations in the US, with an estimated 3000 pregnancies affected each year. [2]What official bodies advise
| Country and body | What it says | Source and year |
|---|---|---|
| United States, USPSTF | All persons planning to or who could become pregnant should take a daily supplement with 0.4 to 0.8 mg (400 to 800 micrograms) of folic acid. It found high certainty of substantial net benefit. [2] | JAMA reaffirmation, 2023 |
| United Kingdom, NHS | 400 micrograms of folic acid daily, ideally from 3 months before pregnancy, and for the first 12 weeks. [1] | NHS page reviewed June 2026 |
| Canada, Public Health Agency of Canada | A multivitamin with 0.4 mg of folic acid daily for people who could become pregnant, are planning a pregnancy or are pregnant. [3] [4] | Pregnancy guide and Health Infobase, 2026 |
| European Union, EFSA | Could not be verified. We were unable to open EFSA's opinion this session, so we state no EU figure. | Not verified |
The bodies differ in wording and in the amounts they name. Do not read one country's figure as universal.
Higher amounts for some people
- UK: the NHS lists people who are advised a higher amount, which it says is 5 mg and can be prescribed by a GP: a neural tube defect in you or the baby's father, a relative with one, a previous affected pregnancy, diabetes, a blood condition such as sickle cell anaemia or thalassaemia, or taking medicine for epilepsy or HIV. [1]
- Canada: the pregnancy guide says some people may need a higher dose, including after a previous pregnancy with a neural tube defect or with a family history, and to talk to a health care provider before going above 1 mg a day. [3]
- Do not change your medicines to suit a supplement. A prescriber decides.
What trials and population data found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Preventing a first neural tube defect | A Cochrane review pooled five trials (6708 births) and found a protective effect of daily folic acid, alone or with other vitamins and minerals (risk ratio 0.31, 95% CI 0.17 to 0.58, high quality evidence). [5] | Established; high-quality evidence |
| Preventing a repeat | The same review found a protective effect on recurrence (risk ratio 0.34, 95% CI 0.18 to 0.64). It found no change in effect whether daily folic acid was 400 micrograms or higher. [5] | Established |
| Cleft palate, cleft lip, heart defects | The review found no evidence of an effect for cleft palate, cleft lip or congenital heart defects, with low quality evidence. [5] The NHS says folic acid can also help prevent cleft lip and palate or some heart conditions. [1] | Mixed or insufficient |
| Mandatory flour fortification | After the US required fortification of enriched cereal grain products with 140 micrograms of folic acid per 100 g from 1998, neural tube defect birth prevalence declined; it averted an estimated 1,000 affected pregnancies a year. [6] | Population surveillance data |
The Cochrane review notes that effects of different doses, forms and schemes on other birth defects are unclear. [5] Results from trials of folic acid should not be assumed for other forms. See Folate vs folic acid vs methylfolate.
Intake figures and food
Health Canada's Dietary Reference Intakes give an RDA of 600 micrograms of dietary folate equivalents (DFE) a day for pregnancy (ages 19 to 30) and 400 for adult non-pregnant women, with an upper limit of 1,000 micrograms of folic acid that applies to supplements and fortified foods only. [7] The NHS says it is difficult to get the amount you need from food alone during pregnancy. [1]Frequently asked questions
When should folic acid start?
The NHS says ideally 3 months before pregnancy or as soon as you find out. [1] Your midwife or doctor can advise on your situation.
How much does the USPSTF recommend?
A daily supplement with 0.4 to 0.8 mg (400 to 800 micrograms) of folic acid for all persons planning to or who could become pregnant. [2]
Is 400 micrograms enough?
Canada's guide says there is strong evidence that 0.4 mg a day is enough to reduce the risk of neural tube defects, and that some people need more. [3]
Can I get enough from food?
The NHS says it is difficult to get the amount you need from food alone. [1]
Does folic acid prevent cleft lip and heart defects?
The NHS says it can help; a Cochrane review found no evidence of an effect, with low quality evidence. [1][5]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: established nutritional role, evidence in adequately nourished people, mixed and Proper evidence not found.
Safety
- Vitamin B12: the NHS warns that more than 1 mg of folic acid a day can mask the symptoms of vitamin B12 deficiency. [8] See Folic acid fortification and unmetabolized folic acid.
- Genes: MTHFR variants do not change the advice for everyone: see MTHFR variants and folate.
- Products: prenatal products vary in content. See Prenatal and postnatal vitamins and Preconception, pregnancy, postpartum and breastfeeding.
References
- NHS (UK). Pregnancy vitamins and supplements. Page last reviewed 3 June 2026. Read 2026-10-23.
- US Preventive Services Task Force. Folic acid supplementation to prevent neural tube defects: reaffirmation recommendation statement. JAMA 2023;330(5):454-459.
- Public Health Agency of Canada. Your guide to a healthy pregnancy. Page details 2026-05-21. Read 2026-10-23 through a web-fetch tool.
- Public Health Agency of Canada. Folic acid use and neural tube defects, Health Infobase. Last updated 2026-06-09. Read 2026-10-23 through a web-fetch tool.
- De-Regil LM, et al. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database Syst Rev 2015;(12):CD007950.
- Williams J, et al. Updated estimates of neural tube defects prevented by mandatory folic acid fortification, United States, 1995-2011. MMWR 2015;64(1):1-5.
- Health Canada. Dietary reference intakes tables: Reference values for vitamins. Page dated 2025-11-19. Read 2026-10-23 through a web-fetch tool.
- NHS (UK). Vitamins and minerals: B vitamins and folic acid. Page last reviewed 3 August 2020. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.