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MTHFR and Pregnancy: What Your Genotype Means for Folate, Hormones, and Pregnancy Health

Pregnancy is a time when small changes in nutrient metabolism can have outsized effects. The MTHFR gene helps convert dietary folate into methylfolate, the active form your body uses to support DNA stability, hormone metabolism, and fetal growth. Variations in MTHFR can change how efficiently this conversion happens and may influence fertility, miscarriage risk, and pregnancy-related complications such as high blood pressure or pre-eclampsia.

How MTHFR Affects Folate and Pregnancy

  • Folate must be converted to methylfolate to participate in one-carbon metabolism, a pathway that supports DNA synthesis, repair, and methylation.
  • Methylfolate is especially important during conception and early pregnancy when rapid cell division and neural tube formation occur.
  • Reduced MTHFR enzyme activity can lower methylfolate availability, which may increase risk for miscarriage, fertility challenges, and certain pregnancy complications in some people.

Practical Steps to Support Folate and Reproductive Health

The guidance below is intended to help support folate status and overall reproductive wellness. PlexusDx does not provide medical advice. Always discuss genetic results and any changes to diet, supplements, or medications with your healthcare provider.

  • Choose food-first sources of folate. Prioritize leafy greens (spinach, kale), legumes (lentils, chickpeas), asparagus, broccoli, and avocados. These foods provide natural folate plus other co-nutrients.
  • Use methylfolate if supplementing. If you need a supplement, methylfolate is the active form and bypasses the MTHFR step. This is especially helpful for people with reduced MTHFR function. Typical prenatal folate recommendations during preconception and pregnancy are 400–800 mcg daily, but your provider will advise the right dose.
  • Include supporting B vitamins. Methylcobalamin (active B12) and riboflavin (B2) support methylation pathways and help enzymes work efficiently. A balanced B-complex can be beneficial.
  • Favor whole foods and a balanced diet. Adequate protein, healthy fats, and a variety of vegetables and fruits support overall fertility and fetal development.
  • Limit environmental exposures. Reduce smoking, excessive alcohol, and exposure to pesticides or heavy metals when possible. These can increase oxidative stress and interfere with nutrient needs.
  • Monitor medical markers. Regular prenatal care, blood pressure checks, and monitoring of hemoglobin and B12 levels are important. If your provider suspects low folate or B12, they may order specific blood tests.
  • Partner and lifestyle support. Healthy weight, stress management, sleep quality, and partner health all contribute to better pregnancy outcomes.

Genetic Interpretation

The section below describes possible interpretations for the MTHFR variant rs1801131 (also called A1298C). Expand the summary that matches your genotype to read tailored recommendations. PlexusDx does not provide medical advice. Always consult your healthcare provider to interpret genetic results in the context of your full medical history.

2 effect alleles — GG (A1298C homozygous effect)

If your genotype is GG, you carry two copies of the effect allele. This is associated with roughly a 20 percent decrease in MTHFR enzyme activity. That reduction can lower conversion of dietary folate into methylfolate, potentially increasing risk for miscarriage, fertility challenges, and pregnancy complications such as high blood pressure or pre-eclampsia.

Practical recommendations

  • Consider methylfolate supplementation rather than synthetic folic acid. Discuss form and dose with your healthcare provider; many clinicians recommend 400–800 mcg methylfolate during preconception and pregnancy, but individualized dosing may be needed.
  • Ensure adequate active B12 (methylcobalamin) intake through diet or supplements to support methylation and homocysteine metabolism.
  • Include riboflavin (B2) as it can help enzyme activity in methylation pathways.
  • Emphasize folate-rich foods: dark leafy greens, legumes, asparagus, and citrus fruits.
  • Monitor blood pressure closely during pregnancy and report any elevation to your provider as early management reduces risk of complications.
  • Ask your provider about blood testing for folate, B12, and homocysteine if there are fertility concerns or a history of miscarriage.
1 effect allele — GT (A1298C heterozygous)

If your genotype is GT, you carry one copy of the effect allele. This typically results in a mild reduction in MTHFR enzyme function compared with the non-effect genotype. Effects are usually less pronounced than with two effect alleles, but attention to folate status during preconception and pregnancy is still important.

Practical recommendations

  • Prioritize natural folate sources from foods and consider a methylfolate-containing prenatal supplement, especially during preconception and early pregnancy. Discuss appropriate dosing with your healthcare provider.
  • Include methylcobalamin (B12) and riboflavin (B2) in diet or supplements to support optimal methylation.
  • Maintain a balanced diet rich in whole foods and manage environmental exposures that can increase oxidative stress.
  • If you have personal or family history of miscarriage, fertility issues, or pregnancy complications, review testing options with your provider, such as folate, B12, and homocysteine levels.
0 effect alleles — TT (A1298C homozygous non-effect)

If your genotype is TT, you carry two copies of the non-effect allele and are expected to have typical MTHFR enzyme function. Your body is generally efficient at converting dietary folate into methylfolate, which supports DNA stability, hormone metabolism, and healthy pregnancy outcomes.

Practical recommendations

  • Meet folate needs with a balanced diet rich in leafy greens, legumes, and other folate-containing foods.
  • Standard prenatal folate supplementation of 400–800 mcg during preconception and pregnancy remains appropriate; methylfolate or folic acid can be used per your provider's guidance.
  • Maintain overall healthy lifestyle habits: adequate sleep, stress reduction, moderate exercise, and avoidance of tobacco and excessive alcohol.
  • Continue routine prenatal monitoring and discuss any family history or prior pregnancy complications with your healthcare provider.

When to Talk to Your Healthcare Provider

  • If you are planning pregnancy, pregnant, or experiencing fertility difficulties, review your MTHFR result with your provider to determine if specific testing or supplement adjustments are warranted.
  • If you have a history of recurrent miscarriage, elevated blood pressure in pregnancy, or other complications, ask about testing folate, B12, and homocysteine levels and whether methylfolate supplementation is appropriate.
  • Always discuss changes to medications, high-dose supplements, or pregnancy care plans with your provider.

PlexusDx provides education about genetic predispositions only and does not provide medical advice. Use these results as one part of a larger conversation with your healthcare provider who can recommend testing, diagnosis, and treatment tailored to your personal health needs.