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Folic Acid and Prenatal Vitamins: What You Need to Know

Why folic acid matters, what a prenatal vitamin usually contains and why to avoid megadoses.

Before you use this guide: This is general educational information, not an individual medical assessment. We do not identify a clinician reviewer on this page, so please confirm personal health decisions with your doctor, midwife or paediatrician.

Folic acid (the synthetic form of vitamin B9, or folate) helps prevent neural tube defects, such as spina bifida, which affect the baby's brain and spine in the earliest weeks. The neural tube forms in the first month after conception, before many women know they are pregnant, so doctors usually advise starting before conception.

Typical advice

Many health services recommend 400 micrograms (0.4 mg) of folic acid a day from at least a month before conception until about week 12 of pregnancy. Some countries, such as Australia, recommend 500 micrograms. If your pregnancy was not planned, start as soon as you find out, because it can still help.

When a higher dose is advised

A higher dose, often 4 to 5 mg a day and available only on prescription, is advised in some situations. Examples include a previous pregnancy affected by a neural tube defect, a family history, diabetes, a high body mass index, certain epilepsy medicines, and some conditions such as sickle cell disease. Ask your doctor which dose is right for you, ideally before you try to conceive.

Folate in food

Eating folate-rich foods, such as leafy green vegetables, beans, lentils, oranges and fortified bread or cereals, is helpful. But it is hard to get enough from food alone, so a supplement is still recommended.

What is in a prenatal vitamin

Prenatal vitamins usually combine folic acid with other nutrients that matter in pregnancy. The amounts vary between brands and countries.

• Iron: supports your growing blood supply, but some women get constipated. Take iron only if it is advised.
• Iodine: supports your baby's brain development. Many health services recommend about 150 micrograms a day.
• Vitamin D: supports bones and the immune system. In the UK, 10 micrograms a day is recommended throughout pregnancy and breastfeeding.
• Calcium, vitamin B12, choline and omega-3 (DHA): some products include them.

Choosing a supplement

• Pick a product made for pregnancy, and check the label for folic acid or folate.
• Look for independent testing marks, such as USP or NSF in the US.
• Gummy vitamins often lack iron and other nutrients, and may contain less folic acid than you need.
• A generic prenatal is usually as good as an expensive one.
• Do not combine a prenatal with another multivitamin without asking, because doubling up can lead to too much of some nutrients.

Avoid too much

• Too much vitamin A (retinol) from supplements can harm a developing baby. Avoid supplements containing retinol, cod liver oil and liver products, unless advised by your doctor.
• Do not take high-dose or herbal supplements without advice.
• Vitamins support a healthy diet but do not replace one.
• Keep vitamins, especially iron, out of reach of children. Iron overdose is dangerous for them.

Special diets

If you are vegetarian or vegan, ask about vitamin B12, iron, iodine, vitamin D, calcium, zinc and omega-3. You may need specific supplements or fortified foods.

Tips if vitamins make you feel sick

• Take them with food, or at night before bed.
• Try a different brand, or a lower-iron product, and ask your doctor or pharmacist.
• If morning sickness is severe, ask whether you can start vitamins later, but do continue folic acid if you can.

Common questions

• I did not take it before I got pregnant. Is it too late? No. Start now and continue to about week 12. It still helps.
• Can I take more to be safe? Not without advice. The usual dose is enough for most people, and a higher dose should be prescribed.
• Do I need to keep taking it after week 12? Your prenatal vitamin may contain it, and it does no harm. Follow your doctor's advice.
• What if I forget a dose? Take it when you remember, and do not double up.
• Is it needed while trying to conceive? Yes, ideally for at least a month before and through the early weeks.
• Does it help fertility? Folic acid prevents neural tube defects. Evidence that it improves fertility is limited, so the aim is a healthy start.

Tell your doctor

Always tell your doctor or pharmacist about every supplement and herbal product you take, including any you bought online.

Where to check current advice

Recommended doses differ between countries, so check with your own health service, such as the NHS in the UK, the HSE in Ireland, the CDC and ACOG in the US, the SOGC in Canada and the Australian Government Department of Health.

This content is for general information only and is not medical advice. Every pregnancy and every baby is different. Always talk to your doctor, midwife or paediatrician about your own situation, and seek urgent care if you are worried.