HSA | FSA CARDS ARE NOW ACCEPTED

TMPRSS6 and Pregnancy: How Your Genetics Can Affect Iron Levels

Pregnancy increases iron needs to support maternal blood volume expansion and fetal growth. The TMPRSS6 gene helps regulate hepcidin, the hormone that controls how much iron your body absorbs and recycles. Variants in TMPRSS6 can change hepcidin regulation and influence risk of iron-deficiency anemia during pregnancy. Below is an easy to understand explanation of how different genotypes for rs855791 affect risk, together with practical diet, supplement, lifestyle, and monitoring suggestions you can discuss with your healthcare provider.

How TMPRSS6 Affects Iron Metabolism

TMPRSS6 encodes a protein that influences hepcidin production. Higher hepcidin lowers intestinal iron absorption and traps iron in storage cells. Certain variants in TMPRSS6 are associated with higher hepcidin activity or reduced ability to downregulate hepcidin when iron is needed, which can make it harder to maintain adequate circulating iron, especially in pregnancy when demand rises.

2 effect alleles (AA) — Higher risk

If you have the AA genotype for rs855791, you carry two copies of the effect allele. This genotype significantly increases your risk of iron-deficiency anemia during pregnancy, particularly when dietary iron intake is low. TMPRSS6 influences hepcidin, the hormone that controls iron absorption and recycling. With two A alleles, your body may have a reduced ability to properly regulate iron absorption, meaning you need higher dietary iron to maintain healthy blood levels during pregnancy when iron requirements are highest.

Potential pregnancy impacts: increased risk of low birth weight, preterm birth, and maternal symptoms such as fatigue and weakness if anemia develops.

Recommendations to discuss with your healthcare provider:

  • Prioritize iron-rich foods: beef, liver, seafood, poultry, legumes, fortified cereals, and dark leafy greens.
  • Prefer heme iron sources (meat, poultry, fish) when possible because they are absorbed more efficiently.
  • Pair iron foods with vitamin C sources such as citrus, bell peppers, strawberries, or tomatoes to boost absorption.
  • Avoid drinking tea or coffee with meals and avoid taking calcium supplements with iron-rich meals, as these inhibit absorption.
  • Consider early and more frequent prenatal iron status monitoring, including hemoglobin and ferritin tests.
  • Follow prenatal supplement guidance from your provider; higher dose iron supplementation may be indicated if tests show deficiency.
1 effect allele (AG) — Moderate risk

If you have the AG genotype for rs855791, you carry one copy of the effect allele. This variant affects how your body regulates iron absorption and recycling through hepcidin. During pregnancy, when iron needs increase, carrying one A allele may moderately increase your risk of iron-deficiency anemia, particularly if your dietary iron intake is low.

Recommendations to discuss with your healthcare provider:

  • Eat a balanced mix of heme and non-heme iron sources: lean meats, seafood, legumes, fortified grains, and dark leafy greens.
  • Use vitamin C at meals to enhance absorption. For example, add citrus or bell peppers to salads or legumes.
  • Limit substances that block absorption around meals: wait at least one hour after eating before drinking tea or coffee and separate calcium supplements from iron-containing meals.
  • Have routine prenatal screening for hemoglobin and ferritin. If levels fall, follow your provider's recommendations for supplementation.
  • Consider small, frequent iron-rich meals or snacks if large meals are poorly tolerated during pregnancy.
0 effect alleles (GG) — Typical risk

If you have the GG genotype for rs855791, you carry two copies of the non-effect allele. The GG genotype is associated with typical iron regulation during pregnancy. Your body's natural ability to control iron absorption and recycling through TMPRSS6 is not impaired by this variant.

Even with typical genetic risk, pregnancy increases iron demands, so maintain a diet and monitoring plan to keep iron status healthy.

  • Include regular sources of iron in meals: lean meats, legumes, fortified cereals, and leafy greens.
  • Pair iron foods with vitamin C for better absorption and avoid inhibitors at mealtime.
  • Follow routine prenatal care with hemoglobin and ferritin checks and take prenatal vitamins as recommended.

Practical Diet and Meal Tips

  • Focus on heme iron first: beef, lamb, pork, chicken, turkey, and fish provide the most absorbable iron.
  • Include plant iron: beans, lentils, tofu, spinach, and iron-fortified cereals. Combine these with vitamin C to improve uptake.
  • Avoid high-calcium foods or supplements at the same time as iron-rich meals. Space calcium supplements at least two hours from iron intake when possible.
  • Limit tea and coffee near meals. Polyphenols in these beverages can reduce iron absorption for several hours after drinking.
  • Cook acidic sauces with iron-rich foods or include citrus-based dressings to enhance absorption.

Supplements and When to Consider Them

  • Follow your prenatal vitamin schedule as recommended by your healthcare provider.
  • If blood tests show low ferritin or anemia, your provider may recommend specific iron supplements. Types and doses vary, and side effects can include constipation or nausea, which are manageable with guidance.
  • Do not start high-dose iron on your own. Excess iron can cause problems and should only be taken based on testing and clinical guidance.

Lifestyle and Other Considerations

  • Plan regular prenatal visits and blood tests. Hemoglobin and ferritin are the primary tests used to track iron status in pregnancy.
  • Monitor symptoms such as persistent fatigue, shortness of breath, dizziness, or paleness and report them to your provider.
  • If you have other conditions that affect iron, such as heavy menstrual bleeding before pregnancy, gastrointestinal disorders, or prior bariatric surgery, discuss this with your care team early.
  • Balance iron-rich eating with comfortable portion sizes if pregnancy nausea or food aversions occur. Small, frequent nutrient-dense meals can help.

Testing and Monitoring

  • Ask your provider for baseline and follow-up hemoglobin and ferritin measurements during pregnancy.
  • Ferritin helps assess iron stores. Low ferritin with low hemoglobin indicates iron-deficiency anemia that typically benefits from supplementation.
  • Providers may adjust iron dosage and frequency of monitoring based on trimester, symptoms, and test results.

Important Disclaimer

PlexusDx provides education about genetic predispositions only. This information does not constitute medical advice. Always consult your healthcare provider for personalized medical guidance, diagnosis, and treatment decisions.