If you are sexually active and could become pregnant — whether you’re planning to or not — you need to take a folic acid supplement every day. This is because folic acid helps your baby’s spine and brain develop and reduces the risk of neural tube defects (NTDs), such as spina bifida.
Around half of all pregnancies are unplanned, and the most important window for folic acid is the first few weeks after conception, often before you know you’re pregnant. That’s why the advice applies to all women who could become pregnant, not only those actively trying.
Folic acid is the man-made form of folate, a B vitamin (B9) that your body uses to make new cells. In early pregnancy, it plays a crucial role in helping your baby’s neural tube — which develops into the brain and spinal cord — close properly.
Neural tube defects happen very early in pregnancy, often within the first 28 days after conception, so having folate already in your system at the moment of conception is what matters most. You can’t catch up on this once you find out you’re pregnant.
For most women planning a pregnancy:
Folic acid is widely available in pharmacies and supermarkets, on its own or as part of a pre-pregnancy / pregnancy multivitamin. Check the label — you want 400 µg of folic acid (sometimes written as 0.4 mg).
It’s hard to get enough folate from food alone, even with a good diet, which is why a daily supplement is recommended in addition to folate-rich foods like leafy greens, beans, peas, lentils, citrus fruit and fortified cereals.
Some women are at higher risk of having a baby with a neural tube defect and need a higher daily dose of 5 mg of folic acid (this is a prescription strength). You should talk to your GP about a higher dose if:
If any of these apply to you, speak to your GP before you start trying for a baby, so the right dose can be started in good time.
Start taking 400 µg of folic acid as soon as you know you’re pregnant, and continue until the end of week 12. Speak to your GP or midwife — they can advise on whether you need any extra checks or a higher dose based on your individual circumstances.
Folic acid does not improve fertility on its own — its job is to protect your baby from neural tube defects. But it is recommended while trying to conceive so it’s already in your system when conception happens.
At the standard 400 µg dose, no. Higher doses (such as 5 mg) should only be taken on medical advice. Don’t try to top up by taking several multivitamins, as you may get too much of other nutrients — some of which (such as vitamin A) can be harmful in pregnancy.
The strongest evidence for folic acid is in the first 12 weeks, when the neural tube is forming. Many women continue to take a pregnancy multivitamin that includes folic acid throughout pregnancy — that’s perfectly safe.
Folic acid recommendations apply to women who could become pregnant. There’s some emerging research suggesting folate intake may support sperm health, but this is not yet a formal recommendation.
