When Should You Start Taking Folic Acid?

Written by Dr Mark Wilshere and Dr Marc Crutchley, GMC-registered GPs and founders of Dr Marks. Medically reviewed by Dr Mark Wilshere MBChB MRCGP DCH BSc (Hons).

The short answer: UK guidance recommends taking 400 micrograms of folic acid every day, ideally starting 3 months before you get pregnant, and continuing until you're 12 weeks pregnant. If you find out you're pregnant and haven't been taking it, start straight away. Some people need a higher dose of 5mg, which a GP can prescribe. Folic acid reduces the chance of your baby having a neural tube defect such as spina bifida.

Why folic acid matters

Folic acid is the manufactured form of folate, a B vitamin. The NHS says that taking folic acid before and in early pregnancy reduces the chance of your baby having a neural tube defect, a problem with the development of the brain, spine or both, such as spina bifida. It can also help prevent other problems, such as cleft lip and palate and some heart conditions.

The neural tube develops very early in pregnancy, often before people know they're pregnant. That's why the timing matters so much.

The NHS also says it's difficult to get the amount you need from food alone, even with a healthy diet. That's why a supplement is recommended. The recommendation is specifically for folic acid, the form used in the research showing fewer neural tube defects.

When to start: if you're planning a pregnancy

Ideally, start 3 months before you get pregnant. Tommy's, the pregnancy charity, explains that it takes time for folic acid to build up to the level that gives the most protection.
Start before you stop contraception. The NHS advises starting folic acid before you stop using contraception, or if there's a chance you might get pregnant.
If you've already stopped contraception, that's fine. Start taking it now.

It isn't harmful to keep taking folic acid for longer if it takes a while to get pregnant.

If you've had a positive test and haven't been taking it

Don't panic. Start taking 400 micrograms of folic acid every day as soon as you can, and continue until you're 12 weeks pregnant. Tommy's notes that if you're already past 12 weeks and didn't know about folic acid, the risk of a neural tube problem is still very small.

Tell your midwife or GP at your first appointment, especially if you have any of the conditions listed below. Our post on tests in pregnancy explains what happens at your appointments.

After a miscarriage

We know this can be a very difficult time. If and when you feel ready to try again, the advice on folic acid is the same: start taking 400 micrograms a day when you begin planning your next pregnancy, so it has time to build up. Tommy's advises waiting until you've had a negative pregnancy test after your loss before trying again, so that a future positive test can be confirmed as a new pregnancy.

Your GP can talk to you about trying again, check for any health conditions and support you emotionally. If you've had more than one miscarriage, or a later loss, talk to your healthcare team.

How long should you take it?

The NHS advises taking folic acid for the first 12 weeks of pregnancy. By then the neural tube has formed. If you take it for longer, it won't harm your baby. Your midwife or doctor may suggest continuing for other reasons, for example if you're at risk of anaemia.

Who needs a higher dose?

The NHS recommends a higher dose of 5mg of folic acid a day if you're planning a pregnancy or less than 12 weeks pregnant and:

you or the baby's biological father has a neural tube defect
you or the baby's biological father has a relative with a neural tube defect
you've 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

The 5mg dose needs a prescription from your GP. NICE Clinical Knowledge Summaries (CKS) also advise that having a body mass index (BMI) of 25 or more, or a higher risk of pre-eclampsia, doesn't on its own mean you need more than 400 micrograms. Don't stop any prescribed medicine because you're planning a pregnancy. Speak to your GP or specialist first.

Folic acid in flour

From 13 December 2026, non-wholemeal wheat flour in the UK will have to have folic acid added (0.25mg per 100g). The government expects this to reduce neural tube defects by around a fifth. It won't replace the supplement: the Department of Health and Social Care says the advice to take folic acid before and in early pregnancy will remain in place.

Other supplements around pregnancy

Vitamin D: the NHS recommends 10 micrograms a day in pregnancy, at least from October to March, and all year if you don't get much sun on your skin. The NHS vitamin D page explains more.
Vitamin A: don't take cod liver oil or supplements containing vitamin A (retinol) in pregnancy, and avoid liver.
Healthy Start: if you're eligible for the NHS Healthy Start scheme, you can get free vitamins containing folic acid, vitamin C and vitamin D while pregnant and until your baby's first birthday.

A varied diet matters too. Good sources of folate include broccoli, brussels sprouts, leafy green vegetables, peas, chickpeas and fortified breakfast cereals. Our food tips have more ideas.

Further reading on our blog:

Omega-3 and fish oil in pregnancy: is it safe?

When to see your GP

See your GP or midwife if you:

are planning a pregnancy and have diabetes, epilepsy, HIV, sickle cell disease or thalassaemia, or a personal or family history of a neural tube defect
take any regular medicines and are planning a pregnancy (don't stop them without advice)
think you need the 5mg dose
are pregnant and haven't yet booked your first midwife appointment
have had a miscarriage and would like to talk about trying again

Frequently asked questions

How much folic acid should I take before pregnancy?

UK guidance recommends 400 micrograms of folic acid a day, ideally from 3 months before you get pregnant until you're 12 weeks pregnant. Some people need 5mg on prescription.

Is it too late to start folic acid if I'm already pregnant?

No. Start as soon as you know and continue until 12 weeks. If you're past 12 weeks, the risk of a neural tube problem is still very small; mention it to your midwife.

Can I get enough folic acid from food?

It's difficult. The NHS says it's hard to get the amount you need from food alone, so a 400 microgram supplement is recommended even if you eat well.

Should I keep taking folic acid after 12 weeks?

You don't need to, but it won't harm your baby if you do. Your midwife may advise continuing if you're at risk of anaemia.

Who should take 5mg of folic acid?

People with diabetes, sickle cell disease, thalassaemia, a personal or family history of neural tube defects, or who take medicine for epilepsy or HIV. Your GP can prescribe it.

Does flour with added folic acid mean I don't need a supplement?

No. Even once flour is fortified from 13 December 2026, the advice to take a 400 microgram folic acid supplement will stay the same.

References

NHS. Pregnancy vitamins and supplements. https://www.nhs.uk/pregnancy/keeping-well/pregnancy-vitamins-and-supplements/ (accessed 19 October 2026)
NHS. Vitamins and minerals: B vitamins and folic acid. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/ (accessed 19 October 2026)
NHS. Folic acid. https://www.nhs.uk/medicines/folic-acid/ (accessed 19 October 2026)
NICE Clinical Knowledge Summaries. Pre-conception: advice and management (advice for all women: folic acid). https://cks.nice.org.uk/topics/pre-conception-advice-management/management/advice-for-all-women/ (accessed 19 October 2026)
Tommy's. Benefits of taking folic acid and vitamin D before pregnancy. https://www.tommys.org/pregnancy-information/planning-a-pregnancy/are-you-ready-to-conceive/benefits-taking-folic-acid-pregnancy (accessed 19 October 2026)
Tommy's. Folic acid in pregnancy. https://www.tommys.org/pregnancy-information/im-pregnant/nutrition-in-pregnancy/folic-acid-pregnancy (accessed 19 October 2026)
Tommy's. Trying again after a miscarriage: what you need to know. https://www.tommys.org/baby-loss-support/miscarriage-information-and-support/pregnancy-after-miscarriage/getting-pregnant-after-miscarriage (accessed 19 October 2026)
GOV.UK. Folic acid (guidance, updated 10 July 2026). https://www.gov.uk/government/publications/folic-acid/folic-acid (accessed 19 October 2026)
GOV.UK. Bread and flour: labelling and composition. https://www.gov.uk/guidance/bread-and-flour-labelling-and-composition (accessed 19 October 2026)
Department of Health and Social Care (2024). Birth defects prevented by fortifying flour with folic acid. https://www.gov.uk/government/news/birth-defects-prevented-by-fortifying-flour-with-folic-acid (accessed 19 October 2026)
NHS Healthy Start. Getting vitamins. https://www.healthystart.nhs.uk/getting-vitamins/ (accessed 19 October 2026)
Tommy's. Your care after 1 or 2 miscarriages. https://www.tommys.org/baby-loss-support/miscarriage-information-and-support/tests-and-treatments-after-miscarriage/your-care-after-1-or-2-miscarriages (accessed 19 October 2026)

This article is general information and is not a substitute for personal medical advice. If you are pregnant, planning a pregnancy or breastfeeding, speak to your midwife, GP or pharmacist before taking any supplement. Food supplements should not replace a varied, balanced diet and healthy lifestyle. Dr Marks is an independent company and is not affiliated with or endorsed by the NHS.