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Folic acid in pregnancy

Folic acid (also known as vitamin B9) is probably the most important supplement to take during pregnancy, and taking it is one of the easiest and best things you can do for your unborn baby. Taking 400mcg of folic acid a day from the time you start trying to conceive until you are 12 weeks pregnant will help prevent neural tube defects such as spina bifida.

By Mumsnet HQ | Last updated Jun 30, 2021

pregnant woman with glass of water and medication

How much folic acid do I need to take in pregnancy?

The National Institute for Health and Clinical Excellence (NICE) recommends that women take a supplement of 400 micrograms of folic acid every day from when they start trying to conceive and for the first 12 weeks of pregnancy.

Although you can get folic acid through food (see below) – and many foods are fortified with folic acid – it's important to take a supplement too. This is because you need a much higher amount during pregnancy and while trying to conceive (almost double the recommended daily intake for when you aren't pregnant).

Why is folic acid important?

Folic acid helps the body create new cells, which is why it is so crucial in the very early stages of pregnancy. As well as protecting against spina bifida (where the bones of the spine don't form properly around the spinal cord), folic acid is also thought to reduce the risk of other problems such as cleft palate and certain heart defects. Some studies have also suggested that it might protect against premature birth and low birth weight too.

When should I start taking folic acid?

Start taking folic acid soon as you begin trying to conceive. The Association for Spina Bifida and Hydrocephalus recommends you take folic acid supplements three months before conception, so if you'd like to get ahead of the game it certainly can't do any harm.

How long do I need to take folic acid for?

You're advised to take it up to the 12th week of pregnancy but lots of multi-vitamin and mineral supplements containing it can be taken throughout pregnancy quite safely, so you can continue for as long as you like.

What if my pregnancy was unplanned and I didn't take folic acid?

If your pregnancy was a 'surprise' (or even a severe shock), don't worry. Neural tube defects are uncommon, even if you didn't take folic acid. Think of all the women with healthy babies who merrily drank, smoked and did showjumping (though probably not all at once) in the weeks before they realised they were pregnant.

Try not to panic and just start taking it as soon as you get a positive pregnancy test.

Do I need to take a higher dose of folic acid?

Some women in certain higher-risk groups for neural tube defects will need a higher dose of folic acid (4-5mg daily). This includes women with:

  • A history of neural tube defects in their family (on either the mother's or father's sides)
  • Epilepsy, who are taking medication for it
  • Insulin-dependent diabetes
  • A previous pregnancy where neural tube defects were identified in their baby
  • Coeliac disease
  • A body mass index higher than 30

Taking a higher dose of folic acid should be discussed with your doctor, who can prescribe the higher dose but may need to check for vitamin B12 deficiency first.

Does folic acid have any side effects?

There are no serious side-effects to taking folic acid, although some women may feel nauseous or bloated, particularly when they first start to take it. There is no problem in taking it for prolonged periods while trying to conceive.

Can you take too much folic acid?

You aren't going to overdose by eating too much broccoli, but it's not a great idea to take more of any supplement than the recommended dose. There's no need to worry if you forget one day, but do try to remember to take one tablet a day as the body can't 'store' folic acid and needs a constant supply. Don't take two the following day if you forget one though.

What time of day should I take my supplement?

It doesn't really matter. It's thought taking them with food may aid absorption but it doesn't have to be with your breakfast. Lots of women find swallowing a pill makes them gag first thing in the morning when pregnant so you can always take it with your dinner instead.

What foods are high in folic acid?

Although pretty much the only way to ensure you're getting the right amount of folic acid for pregnancy is by taking a supplement, stocking up on foods where it occurs naturally as part of your pre-pregnancy diet will only benefit your pregnancy.

Foods rich in folic acid include:

  • Green, leafy vegetables like spinach and Brussels sprouts
  • Cruciferous vegetables like broccoli
  • Potatoes and peas
  • Granary bread
  • Brown rice
  • Fortified breakfast cereals and breads (check the packet)
  • Marmite
  • Eggs
  • Tinned salmon
  • Orange juice

Looks like a particularly gripping episode of Ready Steady Cook, doesn't it?

It's worth knowing that folic acid can be destroyed by overcooking or boiling, so try to steam or microwave these foods to preserve as much of the goodness as possible.

Liver is also high in folic acid but is not safe to eat in pregnancy due to its high levels of vitamin A, which can cause birth defects. It's worth keeping on top of other pregnancy dos and don'ts, too, as there are a few other food items that would normally be good for you, but are off the menu in pregnancy.

What other supplements do I need to take during pregnancy?

A generic pregnancy multivitamin usually contains your daily dose of folic acid along with a multitude of other added extras, but the essential supplements to look for in there are vitamin D and folic acid.

Vitamin D helps to maintain calcium levels and will help your baby develop strong teeth and bones, but it can be difficult to get enough through diet alone. You can get Vitamin D from exposure to sunlight, but that's not always readily available in the UK. A deficiency in vitamin D can result in rickets, which, despite sounding like it should only belong in a Victorian novel, has recently been on the increase. A 10mcg dose daily is an appropriate amount.

Vitamin C, while essential for your health and your baby's development, should not be taken in excessive 'mega' supplement amounts as it has been linked to premature labour. It's easy to get enough vitamin C in your diet by eating lots of fresh fruit and vegetables, and through pre-natal multivitamins.

Unless you have anaemia, iron supplements should be avoided in pregnancy as too much iron can affect foetal growth.

What Mumsnetters say about taking folic acid in pregnancy

“I started taking them about three months before I conceived, but I would forget to take them once or twice a week. I am almost 12 weeks so will stop soon, and then I will find something else to feel guilty about!”

“I took them for a while when trying to conceive but stopped when it looked unlikely that I was going to get pregnant any time soon. I started again when I found out I was pregnant but then I got hyperemesis and couldn't keep anything down for 10 weeks. The doctor just said to take them when I could and not worry too much.”

Talk to other mums-to-be about folic acid and other pregnancy-related topics on our pregnancy Talk boards.