Pregnancy Folate Explained: Folic Acid, Methylfolate (5-MTHF), MTHFR, Vitamin B12, and What the Evidence Really Means

Feeling confused about folic acid, folate, methylfolate, and which to take during pregnancy? You're not alone. Choosing a prenatal supplement should be simple, but for many women, it quickly becomes overwhelming. Your GP or obstetrician might recommend folic acid, while your naturopath leans toward methylfolate. Add in social media opinions, conversations about vitamin B12, unmetabolised folic acid and genetic testing, and it's no wonder why so many women are left wondering if they're taking the right supplement to support their pregnancy.

The reassuring news is that the science is much clearer than the online conversation often suggests. While much of the discussions are based on genuine research, they are frequently taken out of context, applied to doses well above those typically recommended during pregnancy, or interpreted without considering the overall strength of the evidence.

Like most areas of nutrition, the answer isn't about choosing sides; it's about understanding the balance of evidence and making informed decisions that work best for your body.

Folate vs Folic Acid vs Methylfolate: What’s the Difference?

Folate is an essential B vitamin that plays a vital role in healthy cell growth and your baby's early brain and spinal cord development.(1) While it is naturally found in foods such as leafy green vegetables, legumes and citrus fruits, meeting the increased demands of pregnancy through diet alone can be challenging.(1,2) Current data shows that up to 1 in 2 Australian women do not consume adequate folate from food (including from natural and fortified sources).(3) Natural food folates are also relatively fragile and can be lost during cooking, processing and storage. Given how critical this nutrient is during the earliest weeks of foetal development, often before a woman knows she is pregnant, supplementation with folic acid before and during early pregnancy is recommended alongside a nutritionally balanced diet.(4,5)

Folic acid is a stable, highly bioavailable, synthetic form of folate used in supplements and food fortification programs worldwide.(5) Once absorbed, it undergoes a series of metabolic steps before being converted into the active forms of folate used by the body. Its stability allows it to withstand manufacturing, storage and cooking, helping to provide a consistent and reliable source of folate at a time it matters most during baby's early development.(6)

Methylfolate (5-MTHF) is the biologically active form of folate, meaning it is ready for the body to use without first needing to be converted. Because some women naturally convert folic acid less efficiently than others, methylfolate has shown to support maternal health during pregnancy.(7)

Why is Folic Acid Supplementation Recommended in Pregnancy?

Long before most women know they're pregnant, one of the most important stages of their baby's development is already underway.

During the first few weeks after conception, the neural tube forms; the structure that later develops into the brain and spinal cord.(8) When dietary folate intake is inadequate, neural tube defects, such as spina bifida and anencephaly, can occur.

Folic acid is one of the most thoroughly researched nutrients in pregnancy. Decades of research, including randomised controlled trials and studies involving genetically diverse populations, have consistently shown that taking 400 micrograms (mcg) of folic acid daily, starting at least one month before conception and continuing through the first trimester, helps to prevent neural tube defects, such as spina bifida and anencephaly, by up to 70%.(9)

This evidence underpins the recommendations of the World Health Organization (WHO)(10), the National Health and Medical Research Council (NHMRC)(11) and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG)(12). It is one of the most consistent recommendations in all of prenatal nutrition.

What is Unmetabolised Folic Acid (UMFA)?

You've probably seen the term UMFA online, often presented as something to be concerned about. Here's what it means.

Before your body can use folic acid, it first needs to convert it into its active form through an enzyme called dihydrofolate reductase (DHFR). If more folic acid is consumed than the body can convert at one time, a small amount may remain circulating in the bloodstream. This is known as unmetabolised folic acid, or UMFA.(13)

The important question isn't whether UMFA exists – it does. The question researchers are trying to answer is whether small amounts detected in the bloodstream have a meaningful impact on health.

At present, there is no clear evidence that UMFA associated with folic acid from food or supplementation is linked to harm when taken at the recommended doses. (14,15) Instead, researchers continue to investigate its potential significance while acknowledging that more research is needed.

Why Does the Amount of Folic Acid Matter?

This is one of the most important parts of the conversation, and one that is often missing online.

Much of the research exploring UMFA and its potential impact on pregnancy health outcomes has centred around folic acid intakes well above the standard pregnancy recommendation in Australia, typically ranging between 800 mcg to 4,000 mcg per day. (15) This research becomes particularly relevant in countries where the recommended daily intake of folic acid during pregnancy is 800 mcg or above, such as in Canada and the USA.(3)

By comparison, studies investigating supplements containing 400 mcg of folic acid – the amount recommended by WHO, NHMRC and RANZCOG – have found no significant increase in maternal or cord blood UMFA compared with placebo in randomised control studies.(14)

In other words, as with many nutrients, dose matters. Too little folic acid may increase the risk of neural tube defects, while higher doses are more likely to increase circulating UMFA, the long-term health implications of which remain uncertain.(15)

Current evidence continues to support 400 mcg of folic acid for women at average risk, while emerging research highlights the potential role of metabolically active folate in supporting individual differences in folate metabolism.(16) Together, these findings suggest that both the dose and form of folate are important considerations when choosing a prenatal supplement.

What About Vitamin B12? Can Folate Mask Vitamin B12 Deficiency?

Another topic that often appears alongside folic acid is vitamin B12.

Vitamin B12 works closely with folate in DNA synthesis, red blood cell production and nervous system function.(17) During pregnancy, adequate B12 supports maternal health and healthy foetal development.

You may have heard that folic acid can "mask" a vitamin B12 deficiency.

This concern is based on genuine science. High intakes of folic acid can correct the blood signs and symptoms caused by vitamin B12 deficiency; allowing the underlying deficiency to remain undetected.(14)

However, once again, dose matters.

The concern about folic acid masking a vitamin B12 deficiency is only considered relevant at high intakes, specifically at or above 1,000 mcg per day, which is the established safe upper limit for adults in Australia and New Zealand.(18,19) Even at this upper limit, the risk of masking is still considered low for women with adequate vitamin B12 levels.(20) The standard recommended dose of 400 mcg daily during pregnancy is less than half this upper limit, and therefore this dose is not considered a meaningful concern for B12 deficiency masking in otherwise healthy women.(18,19,20)

For women following vegetarian or vegan diets, those with gastrointestinal conditions affecting B12 absorption, women taking certain medications, or those with multiple closely spaced pregnancies, ensuring adequate B12 intake is an important part of prenatal nutrition.(21)

One of the most biologically active forms of B12 is mecobalamin (also known as methylcobalamin), which can be absorbed effectively through the lining of the mouth as well as through the digestive tract.(22) This makes oral-dissolving supplements a practical option for women experiencing nausea, food aversions or digestive discomfort during pregnancy.

What if I Have a MTHFR Gene Variant?

Perhaps no topic generates more confusion in pregnancy than MTHFR, and a lot of what circulates online can be misleading.

The 5,10-methylenetetrahydrofolate reductase enzyme (MTHFR) helps convert folate into the form your body actually uses.(23) Some people carry a variant of this gene that makes this process work a little less efficiently.(23) This has led many women to wonder whether they should ditch folic acid and switch to methylfolate instead, but for most pregnant women, the science does not back this up.

Here is what the evidence actually shows:

• Most MTHFR variants have a low impact on your health. Only around 10% of people carry the specific variant most strongly linked to significantly reduced folate conversion; the homozygous C677T variant.(24) For those who have just one copy of a common MTHFR variant has such a modest effect that it is not considered clinically meaningful at the doses used in standard pregnancy supplements.(24) For more information about which form is folate is suitable for your MTHFR variant, click here.
• Folic acid has evidence across varied genotypes. Large studies conducted across genetically diverse populations have consistently shown that folic acid reduces the risk of neural tube defects, including in women who carry common MTHFR variants.(25) The American College of Medical Genetics and Genomics (ACMG) states that MTHFR status does not change the recommendation to take folic acid during the reproductive years.(26)
• Australian clinical guidelines agree. The RACGP confirms that folic acid protects against neural tube defects in women with and without MTHFR variants and does not recommend routine MTHFR testing.(24) RANZCOG recommends at least 400 mcg of folic acid daily from one month before conception through to 12 weeks pregnancy.(27)
• Having a MTHFR variant does not mean a higher risk of neural tube defects. Neural tube defects occur far less commonly in the population than MTHFR variants do, which tells us that MTHFR is just one piece of a much more complex picture, and that folic acid supplementation is effective across mixed genotypes.(23)

For most women, following the current recommendations is the evidence-based approach to support a healthy pregnancy. If you have had a previous pregnancy affected by a neural tube defect, have confirmed homozygous MTHFR status with elevated homocysteine levels, or have specific concerns about your folate needs, your GP, obstetrician, or midwife can help work out what is right for you.

Where Does Methylfolate (5-Methyltetrahydrofolate) Fit In?

While folic acid remains the only form with decades of evidence demonstrating neural tube defect prevention when taken at least four weeks before conception and during the first trimester of pregnancy, methylfolate may still have an important role to play.(1)

Unlike folic acid, Methylfolate (5-MTHF) is already in its active form, meaning it doesn't need to be converted by the MTHFR enzyme before your body can use it. This may be particularly relevant for women with a MTHFR genetic variation that can make this conversion less efficient.(28)

This isn't a case of one form replacing the other. Folic acid remains the form recommended by leading health organisations for neural tube defect prevention, based on the strength of the current evidence. Rather, folic acid and methylfolate can be thought of as complementary; with folic acid as the more stable, evidence-based form and methylfolate as the biologically active form suitable for women with reduced enzyme activity.(28)

A thoughtfully formulated prenatal supplement can combine the proven benefit of 400 mcg of folic acid with metabolically active methylfolate; pairing decades of research and reliability with newer advances in nutritional science.

When Should I Seek Personalised Advice?

Most women can confidently follow standard pregnancy recommendations. However, it's worth speaking with your healthcare practitioner if you:

• have previously had a pregnancy affected by a neural tube defect
• have confirmed vitamin B12 deficiency
• follow a vegan, vegetarian or restrictive diet
• have digestive conditions affecting nutrient absorption
• have elevated homocysteine levels
• have a confirmed MTHFR variant and would like personalised guidance

The Bottom Line

If you have been feeling overwhelmed by conflicting information online, you are not alone.

The reassuring news is that the core nutritional recommendations for pregnancy are well-established and backed by decades of high-quality research. You do not need to choose between the science you can trust and newer nutritional thinking. At their best, the two work together, giving you a more complete picture of what your body needs during one of the most important periods of your life.

At H.E.R Code, we believe every woman has her own unique biological code. Our formulation is built on that foundation; honouring the decades of evidence that support folic acid as a key nutrient in reducing the risk of neural tube defects, while incorporating emerging research into genetics and nutrient metabolism that helps us better understand individual differences in how women process and respond to nutrients.

This article is intended for general nutritional education only and does not replace personalised medical advice. Always consult your GP, obstetrician, midwife, or qualified healthcare practitioner for guidance specific to your individual needs during pregnancy.

References

1. De‐Regil LM, Peña‐Rosas JP, Fernández‐Gaxiola AC, Rayco‐Solon P. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane database of systematic reviews. 2015(12). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC8783750/
2. Australian Health Survey: Usual Nutrient Intakes. Australian Bureau of Statistics; 2011-12 financial year [Internet]. Released 6 Mar 2015. Available from: https://www.abs.gov.au/statistics/health/food-and-nutrition/usual-nutrient-intakes/latest-release (accessed 1 Mar 2026)
3. Ledowsky C, Mahimbo A, Scarf V, Steel A. Women taking a folic acid supplement in countries with mandatory food fortification programs may be exceeding the upper tolerable limit of folic acid: a systematic review. Nutrients. 2022 Jun 29;14(13):2715. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC9268323/
4. National Health and Medical Research Council, Australian Government Department of Health and Aged Care, New Zealand Ministry of Health. Nutrient Reference Values for Australia and New Zealand: Folate [Internet]. Canberra (AU): Eat for Health; [cited 2026 Jul 12]. Available from: https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/folate
5. Li J, Duan H, Ramaswamy H, Wang C. A comprehensive review of fortification, bioavailability, and health benefits of folate. International Journal of Molecular Sciences. 2025 Aug 9;26(16):7703. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC12386915/
6. Sulistyoningrum DC, Sullivan TR, Skubisz M, Palmer DJ, Wood S, Ueland PM, McCann A, Makrides M, Green TJ, Best KP. Maternal serum unmetabolized folic acid concentration following multivitamin and mineral supplementation with or without folic acid after 12 weeks gestation: A randomized controlled trial. Matern Child Nutr. 2024 Oct;20(4):e13668. Available from:  https://pubmed.ncbi.nlm.nih.gov/38783413/
7. De‐Regil LM, Fernández‐Gaxiola AC, Dowswell T, Peña‐Rosas JP. Effects and safety of periconceptional folate supplementation for preventing birth defects. Cochrane database of systematic reviews. 2010(10). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC4160020/
8. Pregnancy, Birth and Baby. Neural tube defects [Internet]. Melbourne: Healthdirect Australia; 2024 [cited 2026 Jul 8]. Available from: https://www.pregnancybirthbaby.org.au/neural-tube-defect
9. Dorney E, Black KI. Preconception care. Aust J Gen Pract. 2018;47(7):424-429. doi:10.31128/AJGP-02-18-4485. Available from: https://www1.racgp.org.au/ajgp/2024/november/preconception-care
10. World Health Organization. Periconceptional folic acid supplementation to prevent neural tube defects [Internet]. Geneva: WHO; 2023 [cited 2026 Jul 1]. Available from: https://www.who.int/tools/elena/interventions/folate-periconceptional
11. National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand: Folate [Internet]. Canberra: NHMRC; 2006 [cited 2026 Jul 1]. Available from: https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/folate
12. Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Vitamin and mineral supplementation in pregnancy [Internet]. Melbourne: RANZCOG; [cited 2026 Jul 1]. Available from: https://ranzcog.edu.au/wp-content/uploads/Vitamin-Mineral-Supplementation-Pregnancy.pdf
13. Ledowsky C, Mahimbo A, Scarf V, Steel A. Women taking a folic acid supplement in countries with mandatory food fortification programs may be exceeding the upper tolerable limit of folic acid: a systematic review. Nutrients. 2022 Jun 29;14(13):2715. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC9268323/
14. Pentieva K, Selhub J, Paul L, Molloy AM, McNulty B, Ward M, Marshall B, Dornan J, Reilly R, Parle-McDermott A, Bradbury I. Evidence from a randomized trial that exposure to supplemental folic acid at recommended levels during pregnancy does not lead to increased unmetabolized folic acid concentrations in maternal or cord blood. The Journal of nutrition. 2016 Mar 1;146(3):494-500. Available from: https://www.sciencedirect.com/science/article/pii/S0022316623005369?via%3Dihub
15. Ledowsky C, Scarf V, Sobczyńska-Malefora A, Carter T, Timbrell NE, Steel A. Health effects of excess folic acid use and high blood folate during preconception and pregnancy: a systematic review. Reproductive BioMedicine Online. 2025 Sep 12:105240. Available from: https://www.sciencedirect.com/science/article/pii/S147264832500447X
16. Cochrane KM, Elango R, Devlin AM, Mayer C, Hutcheon JA, Karakochuk CD. Supplementation with (6S)-5-methyltetrahydrofolic acid appears as effective as folic acid in maintaining maternal folate status while reducing unmetabolised folic acid in maternal plasma: a randomised trial of pregnant women in Canada. British Journal of Nutrition. 2024 Jan;131(1):92-102. Available from: https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/supplementation-with-6s5methyltetrahydrofolic-acid-appears-as-effective-as-folic-acid-in-maintaining-maternal-folate-status-while-reducing-unmetabolised-folic-acid-in-maternal-plasma-a-randomised-trial-of-pregnant-women-in-canada/A07396C9FBD5A56E4B3D6BCB5D465CBA
17. National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand: Vitamin B12 [Internet]. Canberra: NHMRC; 2006 [cited 2026 Jul 1]. Available from: https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/vitamin-b12
18. Mills JL, Molloy AM, Reynolds EH. Do the benefits of folic acid fortification outweigh the risk of masking vitamin B12 deficiency? BMJ. 2018;360:k724. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6889897/
19. Reynolds EH, Sobczyńska-Malefora A, Green R. Fortification, folate and vitamin B12 balance, and the nervous system. Is folic acid excess potentially harmful?. European Journal of Clinical Nutrition. 2025 Nov;79(11):1073-7. Available from: https://www.nature.com/articles/s41430-025-01652-8
20. Food Standards Australia New Zealand (FSANZ). Risk of masking vitamin B12 deficiency [Internet]. Canberra: FSANZ; [date unknown]. Available from: https://www.foodstandards.gov.au/sites/default/files/food-standards-code/proposals/Documents/Risk%20of%20masking%20vitamin%20B12%20deficiency.pdf
21. Frayne J, Pinchon D. Anaemia in pregnancy. Aust J Gen Pract [Internet]. 2019 Mar [cited 2026 Jul 18];48(3):125–132. Available from: https://www1.racgp.org.au/getattachment/f4c2d04b-4c99-477d-acf6-b88ede6325ba/Anaemia-in-pregnancy.aspx
22. Andrès E, Jannot X, Terrade JE. Vitamin B12: Integrative Metabolism and Comparative Pharmacology of the Four Cobalamin Forms-Cyanocobalamin, Hydroxocobalamin, Methylcobalamin, and Adenosylcobalamin. Arch Biotech Pharma Res. 2026 Mar 27;2(1):31-43. Available at: https://urfpublishers.com/journal/biotech-pharma-research/article/view/vitamin-b12-integrative-metabolism-and-comparative-pharmacology-of-the-four-cobalamin-forms-cyanocobalaminhydroxocobalaminmethylcobalamin-and-adenosylcobalamin
23. Hickey SE, Curry CJ, Toriello HV. ACMG Practice Guideline: lack of evidence for MTHFR polymorphism testing. Genet Med [Internet]. 2013 [cited 2026 Jul 18];15(2):153–156. Available from: https://www.nature.com/articles/gim2012165
24. Long S, Goldblatt J. MTHFR genetic testing: controversy and clinical implications. Aust Fam Physician [Internet]. 2016 Apr [cited 2026 Jul 18];45(4):237–240. Available from: https://www.racgp.org.au/afp/2016/april/mthfr-genetic-testing-controversy-and-clinical-imp
25. Stover PJ, MacFarlane AJ, Field MS. Bringing clarity to the role of MTHFR variants in neural tube defect prevention. The American Journal of Clinical Nutrition. 2015 Jun 1;101(6):1111-2. Available at: https://www.sciencedirect.com/science/article/pii/S0002916523274031?via%3Dihub
26. Dean L. Methylenetetrahydrofolate reductase deficiency. In: Pratt VM, Scott SA, Pirmohamed M, et al., editors. MINI Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012– [updated 2024 Nov 4; cited 2026 Jul 18]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK66131/
27. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Pre-pregnancy counselling. C-Obs 3a [Internet]. Version 13.1. Melbourne: RANZCOG; 2024 Nov [cited 2026 Jul 18]. Available from: https://ranzcog.edu.au/wp-content/uploads/Pre-Pregnancy-Counselling.pdf
28. Tate C, Shuman A, Nice S, Salehi P. The critical role of folate in prenatal health and a proposed shift from folic acid to 5-methyltetrahydrofolate supplementation. Georgetown Medical Review. 2024 Oct 31;8(1). Available from: https://gmr.scholasticahq.com/article/124570-the-critical-role-of-folate-in-prenatal-health-and-a-proposed-shift-from-folic-acid-to-5-methyltetrahydrofolate-supplementation