Folic Acid, Pregnancy, and Misinformation: What the Evidence Really Says

If you’ve been on social media lately, you may have seen claims that pregnant people should avoid folic acid because it could increase the risk of autism. This is not only incorrect - it is dangerous. Folic acid is one of the most well-studied, impactful public health interventions in maternal–fetal health, credited with preventing thousands of devastating birth defects worldwide. Below, I’ll break down what folic acid does, what the highest-quality evidence shows, and how to tune out the noise.

What is folic acid and why does it matter?

Folic acid is the supplemental (synthetic) form of folate, a B-vitamin that supports DNA synthesis, cell division, and the early development of a baby’s brain and spinal cord. Because the neural tube closes very early - often before someone knows they’re pregnant - consistent folic acid intake before conception and in early pregnancy is critical. Health Canada’s guidance is clear: anyone who could become pregnant should take a multivitamin with 0.4 mg (400 mcg) of folic acid daily, ideally starting at least three months before pregnancy and continuing through early pregnancy. People with certain risk factors may need more, under the advice of a clinician.

The strongest evidence: preventing neural tube defects

Multiple randomized trials and meta-analyses demonstrate that folic acid prevents neural tube defects (NTDs) like spina bifida and anencephaly. The landmark Medical Research Council (MRC) randomized trial showed that periconceptional folic acid prevents the recurrence of NTDs in families with a previously affected pregnancy.

Beyond recurrence prevention, pooled analyses of primary prevention show substantial protection in the general population: a large meta-analysis estimated a 62% reduction in first-occurrence NTDs with folic acid supplementation. This magnitude of benefit is precisely why so many countries fortify staple foods with folic acid to protect people who may become pregnant, including those with limited access to prenatal care or supplements.

Public health agencies and professional bodies have maintained these recommendations for decades, and recent evidence reviews (including those informing the U.S. Preventive Services Task Force) continue to support folic acid supplementation before and during early pregnancy.

What about autism risk?

A common social-media claim is that folic acid somehow raises the risk of autism. This assertion typically relies on selective interpretation of small observational studies that measured unmetabolized folic acid in umbilical cord blood - a marker that does not equal maternal folic acid intake or supplement dose and cannot establish cause and effect. It’s a leap to go from such indirect measures to “avoid folic acid,” and it conflicts with higher-quality evidence.

In contrast, systematic reviews and meta-analyses that pool large datasets show the opposite pattern: folic acid supplementation around conception and in early pregnancy is associated with a lower risk of autism spectrum disorder (ASD) in offspring. One meta-analysis of 10 studies with 23 sub-studies and 9,795 ASD cases reported an odds ratio of 0.57 for ASD with early-pregnancy folic acid use (about a 43% lower risk).

These analyses do not prove that folic acid “prevents autism” outright (ASD is multifactorial), but they undercut the claim that folic acid increases ASD risk and align with the biologic plausibility that adequate folate supports healthy neurodevelopment.

Why “low-quality evidence” drives high-engagement myths

Part of the problem is that short-form content rewards hot takes and oversimplified narratives. Influencers sometimes spotlight a single small, observational study - often in a narrow subgroup - and present it as definitive. But observational studies can be valuable for generating hypotheses, not for proving harm or establishing clinical guidance. Confounders (like preterm birth, which itself is associated with ASD) can skew associations. Without randomization, we must be cautious about inferring causality.

When content creators dismiss strong evidence (randomized trials, consistent meta-analyses) while elevating weaker, indirect measures, they mislead audiences - particularly when the topic is pregnancy, where decisions carry significant consequences. The result is unnecessary fear, confusion, and in the worst case, avoidance of a proven protective intervention.

Fortification: a population-level success story

Over the past few decades, many countries have fortified flour or other staple foods with folic acid, leading to significant reductions in NTDs at the population level. Fortification is designed to complement, not replace, individual supplementation and a folate-rich diet. It ensures a baseline level of protection - especially important because many pregnancies are unplanned and neural tube closure happens before many people realize they are pregnant.

Practical guidance you can trust

If you are pregnant or planning a pregnancy, evidence-based steps include:

• Take a daily prenatal vitamin with 0.4 mg folic acid, starting at least three months before conception and continuing through early pregnancy. Those with higher risk may need a different dose; ask your provider.

• Eat folate-rich foods such as leafy green vegetables, legumes, citrus, and fortified grains. Supplements and fortified foods work together to maintain adequate folate status.

• Rely on credible sources for pregnancy nutrition, such as Health Canada and provincial health authorities, which base guidance on comprehensive reviews rather than single studies.

The bottom line

Folic acid is a cornerstone of prenatal care because it prevents neural tube defects - a benefit confirmed by randomized trials and reinforced by meta-analyses and national guidelines. Claims that folic acid increases autism risk are not supported by the totality of evidence; in fact, pooled analyses suggest a lower ASD risk with periconceptional use. When viral posts promote fear based on low-quality or misinterpreted data, the harm is real: people may abandon safe, proven practices during a critical window of fetal development. Stick with the consensus built on decades of research.

Felicia Newell is a Registered Dietitian, Nutritionist, Food and Nutrition Expert, Health Coach, and proud mom of four. She is also the owner of Sustain Nutrition/FN Health.

Felicia knows firsthand what it’s like to juggle a busy life while trying to stay healthy in an environment that doesn’t always make it easy. The world of health and wellness can be overwhelming, full of mixed messages and misinformation - and she’s passionate about helping people cut through the noise. Her mission is to guide clients in navigating life and health with clarity, confidence, and enjoyment.

With more than 12 years of education and experience in Nutritional Sciences, Felicia brings both expertise and empathy to her work. She holds a Bachelor’s and Master’s degree in Nutritional Sciences, has worked at a leading research centre, taught university courses, and served in various healthcare roles. Over the years, she’s helped countless individuals achieve their health and wellness goals through evidence-based nutrition counselling that fits their real lives.

As a busy mom herself, Felicia understands the challenges her clients face and offers practical, sustainable strategies to support long-term success. Whether you’re looking to improve your overall health, manage a condition, or simply feel your best, Felicia has the skills, knowledge, and dedication to help you get there - on your terms.