How much folic acid for pregnancy, when to start and what if you miss it?

The neural tube is the structure which eventually becomes your baby's spinal cord and brain. It develops early in pregnancy and tends to close about 4 weeks after conception. In an NTD, part of the tube does not close, which can lead to severe neurological problems, disability and death.

It's difficult to get the amount of folate recommended for a healthy pregnancy from food alone, so taking a folic-acid supplement is the best way to help prevent NTDs.

When should I start taking folic acid?

It is recommended that you start taking folic acid when you are trying to get pregnant – ideally for 3 months before you become pregnant – and then continue to take it up to the end of your 12th week of pregnancy.

This might mean that you are taking folic acid for much longer than 3 months if it takes longer than that for you to conceive but that's fine. It's not at all harmful.

If you've found out you're pregnant and you have not been taking folic acid, then start taking it as soon as you can.

How much should I take?

The current recommended dose of folic acid for most women is 400 micrograms (mcg) of folic acid daily until the 12th week of pregnancy.

However, there are some women who may be considered to be at increased risk of having baby affected by an NTD and, if you fall into that category, you will need a different daily dose of folic acid.

You would be considered to be at increased risk of having baby affected by an NTD if:

You or your partner have a NTD
You have had a previous pregnancy affected by an NTD
You have a family history of an NTD condition

You may be considered to be at increased risk of having baby affected by an NTD if:

You are taking anti-epilepsy or anti-seizure medications
You have particular medical conditions such as diabetes
You have obesity (BMI over 30kg/m2)
You have sickle cell disease, thalassaemia or thalasaemia

If you are considered to be high risk, it will be recommended that you take a bigger daily dose of 5 milligrams (mg) of folic acid until the 12th week of pregnancy. Additionally, if you have sickle cell disease, thalassaemia or thalasaemia, you will be advised to continue taking this bigger dose of folic acid beyond 12 weeks and up to the end of your pregnancy.

If you need to take the bigger 5mg dose of folic acid, you will be prescribed it (for free) on prescription.

Read more about taking extra folic acid if you're overweight and pregnant

How long should I take folic acid for?

Unless you're advised otherwise by your GP, the recommendation is that folic-acid supplementation can be stopped after the 12th week of pregnancy.

What if I’m pregnant and haven't been taking folic acid?

If you weren't taking folic acid pre-pregnancy, then you can start to take it once you find out you are pregnant.

If you are already pregnant and haven't started taking it yet, then start as soon as you can.

What if I'm already past 12 weeks pregnant?

Taking folic acid past 12 weeks of pregnancy is still safe to do so and, as it also has a role in the development of red blood cells, you may wish to starting taking it now.

You should inform your antenatal team that you haven't taken folic acid in the first 12 weeks but remember the risk of NTDs are still small. Your baby will be assessed thoroughly during your 12-week dating scan and your 20-week scan.

What if I forget to take my daily dose?

Try not to worry. You can either take it later in the same day or just start again the next day.

What if I take too much folic acid by mistake?

Folic acid is unlikely to cause harm if you take an extra dose. It is considered generally very safe.

Can't I just get folic acid from eating healthily?

You can get the natural form of folic acid (folate or vitamin B9) from foods such as dark leafy vegetables but, as you need around 10 times as much folate as usual during pregnancy, a supplement is recommended during pregnancy to ensure that you have enough.

But isn't folic acid added to foods like flour?

Some foods, such as breakfast cereals and bread made from fortified white flour, has folic-acid fortification (added folic acid). But, even if you eat plenty of these foodstuffs, it's not easy to be sure that you'll eat enough to get the required dose.²

And, since having more than the recommended amount of folic acid is unlikely to do you or your baby harm, the recommendation is to have a folic-acid supplement as well.

Where can I get folic-acid supplements from?

You can get folic-acid supplements from supermarkets and pharmacies, both online and on the high street. If you live in England, Wales or Nothern Ireland, and you are eligible for the NHS Healthy Start scheme you will be entitled to free Healthy Start vitamins which contain folic acid, vitamin C and vitamin D (as long as you are pregnant, breastfeeding or have a child under 1 year old).

Can I take folic acid if I am breastfeeding?

Yes it is safe to take folic-acid supplements during breastfeeding.

References:

^{1. Pre-conception advice for all women, National Institute for Health and Care Excellence, Apr 2023.}
^{2. Vitamins, supplements and nutrition in pregnancy. NHS, 1 September 2023.}
^{3. Folic acid in flour to prevent birth defects is too low, scientists say, Roxby P. BBC News, 2 February 2023.}

Pic: Getty

Dr Philippa KayeGP

Dr Philippa Kaye works as a GP in both NHS and private practice. She attended Downing College, Cambridge, then took medical studies at Guy’s, King’s and St Thomas’s medical schools in London, training in paediatrics, gynaecology, care of the elderly, acute medicine, psychiatry and general practice.

Why do I need to take folic acid?