Folic acid is the one supplement the NHS asks you to start before a positive test. Most people need the standard 400 micrograms you can buy anywhere. A smaller group should ask their GP about a higher 5mg dose. Here is how to tell which group you are in, when to start, and what to do if you are already pregnant and missed it.
Last reviewed 7 October 2026 · Checked against NHS guidance · 9 min read
The short answer
Take 400 micrograms of folic acid every day while you are trying to get pregnant, ideally starting 3 months before, and carry on until you are 12 weeks pregnant. If you or the baby's father has a neural tube defect, or a relative does, or you have had an affected pregnancy, diabetes, sickle cell anaemia or thalassaemia, or you take medicine for epilepsy or HIV, the NHS recommends a higher 5mg dose, which a GP can prescribe. Already pregnant and haven't started? Start now.
Folic acid sits alongside food safety as one of the first things to get right, so if you are also reading up on what to eat, our pregnancy food safety checklist covers that side. This guide goes deep on one question only: how much folic acid, from when, and who needs more.
Why folic acid matters so early
Folic acid is the man-made form of folate, which is vitamin B9. The NHS explains that taking it around conception and in early pregnancy reduces the chance of your baby having a neural tube defect, which it describes as a problem with the brain or spine, or both, such as spina bifida. The NHS adds that it can also help prevent other problems, such as cleft lip and palate or some heart conditions.
The timing is the whole point. The NHS medicines guide says folic acid helps a baby's brain, skull and spinal cord develop properly, and the protective window the NHS sets is the first 12 weeks. Many people do not know they are pregnant for several of those weeks, which is why the advice is to have folic acid on board before you conceive rather than waiting for a positive test. GOV.UK puts it simply: folic acid helps a baby's spine develop and reduces the risk of neural tube defects.
When to start and when to stop
The NHS advice has three parts:
- Start when you are trying to get pregnant, ideally 3 months before.
- Keep going every day, without gaps, through conception.
- Stop once you reach 12 weeks of pregnancy, unless your GP or midwife tells you otherwise.
Three months is the ideal, not a hard rule. If you are trying now and have not started, start today rather than waiting for a "proper" run-in. Every day of folic acid before conception counts. Folic acid is one item on our wider checklist for before you try for a baby.
Not actively planning but could get pregnant? The NHS page on B vitamins says women who could become pregnant should also take a daily 400 microgram folic acid supplement, as well as those who are pregnant or trying.
400 micrograms or 5mg: which dose is yours?
Two doses come up again and again, and the numbers look confusing because one is written in micrograms and the other in milligrams. 5mg is 5,000 micrograms, so the higher dose is more than twelve times the standard one. That is exactly why it is a prescription decision rather than something to pick off a shelf.
Standard dose: most people
- Every day, from before pregnancy until 12 weeks
- Buy from pharmacies, supermarkets and online
- Often labelled 400mcg or 400µg
Higher dose: specific groups
- Recommended by the NHS for the groups listed below
- Can be prescribed by a GP
- Also taken every day until 12 weeks
Who the NHS says should take the higher dose
The NHS pregnancy vitamins page, reviewed June 2026, recommends a higher daily dose if you are planning a pregnancy or are less than 12 weeks pregnant and:
- you or the baby's father has a neural tube defect
- you or the baby's father has a relative with a neural tube defect
- you have had a previous pregnancy affected by a neural tube defect
- you have diabetes
- you have a blood condition such as sickle cell anaemia or thalassaemia
- you take medicine for epilepsy or HIV
Notice that two of the six are about the baby's father, not you. That catches a lot of couples out: a partner's family history of spina bifida is a reason to have the conversation with your GP.
You may see other conditions listed on other websites. We have only included the ones on the current NHS page. If you have a health condition that is not on this list and you are unsure, your GP or pharmacist is the right person to ask.
Should I ask my GP about the higher dose?
Tick anything that applies to you or your partner. Based on the NHS list. Nothing you tick is saved or sent anywhere.
A quick check, not a diagnosis. The Vitamins Before Pregnancy course walks through folic acid and vitamin D in full, including how to read a supplement label.
Speak to your GP before you start trying
If anything on the list applies, book a GP appointment as soon as you start planning, rather than at your first antenatal visit. The higher dose works best when it starts before conception. If you take medicine for epilepsy, HIV or diabetes, do not stop or change it on your own; your GP can review your medicines and folic acid together.
"I didn't take it before I got pregnant." What now?
This is one of the most common worries, and the NHS answer is clear: if you did not take folic acid before you conceived, start as soon as you find out you are pregnant, and continue until 12 weeks.
A few practical points:
- Start today. Buy a 400 microgram tablet from a pharmacy or supermarket; you do not need a prescription for the standard dose.
- Do not take extra to catch up. The NHS medicines guidance says if you forget a dose, take it when you remember and take the next one at the usual time. Do not take two doses to make up for a missed one.
- Tell your midwife or GP at booking, especially if any higher-dose factor applies to you.
- Try not to panic. Starting as soon as you know is part of the official advice, not a fallback. You are doing what the NHS recommends.
Can you get enough folate from food?
Eating folate-rich foods is a good idea, but it does not replace the tablet. The NHS says it is difficult to get the amount you need for pregnancy from food alone, which is why it recommends a supplement on top of a healthy diet. For a closer look, see our guide: Getting Ready for Pregnancy.
Good food sources of folate listed by the NHS include:
For context, the NHS says most adults need 200 micrograms of folate a day, and that the body cannot store it for long, so you need it regularly. The pregnancy recommendation is a separate 400 microgram supplement on top of food, not a target to reach through diet.
On "folate versus folic acid": the NHS simply describes folic acid as the man-made version of folate. Its pregnancy advice is written in terms of a folic acid supplement, so that is what we recommend checking for on the label. If you are weighing up a different form, ask a pharmacist.
Folic acid in flour from the end of 2026
The UK government announced on 14 November 2024 that new legislation would require millers and flour producers to fortify non-wholemeal wheat flour with folic acid from the end of 2026. The current GOV.UK guidance states that non-wholemeal wheat flour will be fortified by law from December 2026, and that some products may contain fortified flour from autumn 2025.
What it covers: non-wholemeal wheat flour, which ends up in many everyday breads and baked goods. GOV.UK says wholemeal, gluten-free and other grain flours will not be fortified.
What it does not change: your supplement. GOV.UK is explicit that fortification is intended to support, not replace, current advice, and that women trying for a baby should still take folic acid supplements. Fortified bread is a helpful safety net for unplanned pregnancies, not a reason to skip the tablet.
Buying and taking folic acid
The standard 400 microgram dose is easy to find. The NHS says you can buy vitamin supplements from pharmacies, supermarkets and online, and you may be able to get free vitamins through the Healthy Start scheme if you are eligible.
- Plain folic acid or a pregnancy multivitamin. Either works, as long as it gives 400 micrograms of folic acid. Check the label rather than the front of the box.
- Avoid vitamin A. The NHS says not to take cod liver oil or supplements containing vitamin A (retinol) when pregnant, as too much can harm your baby.
- Add vitamin D. The NHS pregnancy page also advises 10 micrograms of vitamin D a day between early October and late March.
- Make it a habit. The NHS says you can usually eat as normal while taking folic acid. Taking it at the same time each day, with the pot by your toothbrush, makes it harder to forget.
- Don't double up. The NHS notes that taking 1mg or less of folic acid supplements a day is unlikely to cause harm, and that high doses can hide signs of vitamin B12 deficiency. Stick to the dose you have been advised.
Our sister guide on pregnancy vitamins in the UK covers vitamin D, iron and what to skip once you are pregnant.
Planning a pregnancy? Get the full plan
This article answers the folic acid question. Our preconception courses go further: vitamin D, label checking step by step, and a week-by-week plan for the months before you start trying.
Vitamins Before Pregnancy
Folic acid and vitamin D before pregnancy: how much, when to start, who may need 5mg, and how to check a supplement label.
Complete Preconception Course
A 12-week plan for the run-up to pregnancy, covering food, supplements and everyday habits.
See all preconception courses.
Related guides
- Morning sickness: what to eat: and how to keep taking your tablets.
- Pregnancy meal plan (UK): a balanced day built on the Eatwell Guide.
- Eating fish when pregnant or trying: tuna and oily fish limits.
Questions people ask
How long before pregnancy should I take folic acid?
The NHS says ideally 3 months before you get pregnant. If you are trying and have not started yet, start now; any time before conception helps.
Should I take 400mcg or 5mg folic acid?
Most people need 400 micrograms a day. The NHS recommends 5mg if you or the baby's father has a neural tube defect or a relative with one, you have had an affected pregnancy, you have diabetes, sickle cell anaemia or thalassaemia, or you take medicine for epilepsy or HIV. A GP can prescribe it.
Is it too late to take folic acid if I'm already pregnant?
No. If you did not take it before you conceived, the NHS says to start as soon as you find out you are pregnant and keep taking it until 12 weeks.
When can I stop taking folic acid?
The NHS advice is to take it until you are 12 weeks pregnant. Follow your GP's or midwife's advice if they have told you something different.
Can I get enough folic acid from food?
Not reliably. The NHS says it is difficult to get the amount you need from food alone, so take a supplement as well as eating folate-rich foods such as broccoli, leafy greens, peas and beans.
Will folic acid in flour mean I don't need a supplement?
No. Non-wholemeal wheat flour will be fortified by law from December 2026, but GOV.UK says this supports rather than replaces supplement advice, so you should still take folic acid when trying for a baby. You can browse every course and guide on the My Nutri Care home page.
Sources
- NHS: Vitamins, supplements and nutrition in pregnancy (page last reviewed 3 June 2026)
- NHS: Folic acid (medicines guide) (page last reviewed 5 May 2026), including how and when to take it
- NHS: B vitamins and folic acid
- GOV.UK: Folic acid
- GOV.UK: Birth defects prevented by fortifying flour with folic acid (14 November 2024)
This article is general information based on UK public health guidance. It is not medical advice. If you have a health condition, take regular medicines or have questions about your own situation, speak to your GP, midwife or pharmacist.
