How much folate do I need, and why?

What to do

• 400 micrograms a day, starting at least a month before you try, on its own or in a prenatal. Folic acid and methylfolate both count — more on the difference.
• If you've had a pregnancy affected by a neural tube defect, the US recommendation is much higher: 4,000 micrograms (4 mg) a day, started before conception and continued through the first trimester, under your doctor's guidance.
• The UK also uses a higher dose (5 mg) for diabetes diagnosed before pregnancy, epilepsy treated with anti-seizure medication, sickle cell disease or thalassaemia, and some HIV medications. US guidance doesn't list these, so if one applies to you, ask your doctor which dose is right.
• Higher weight is no longer a reason for a higher dose in UK guidance as of 2025; 400 micrograms is considered enough.

Be careful

Safety consideration Don't take more than 1,000 micrograms a day of folic acid from supplements unless a doctor prescribes it. High doses can hide the anaemia of vitamin B12 deficiency while the nerve damage it causes carries on.

Does it help you get pregnant?

Emerging evidence Possibly. In a study that followed more than 18,000 nurses, women who took a multivitamin most days were less likely to have ovulation problems, and folic acid explained part of that. It's an observational finding, so it can't prove the vitamin was the cause — but it's one more reason to start a prenatal early.