Checking Your Iron in Pregnancy
Checking Your Iron Levels: Why It Matters for Fertility and Pregnancy
Written by Dr. Fiona Callender, ND
Iron deficiency is one of the most common nutritional concerns in pregnancy, affecting nearly 50% of pregnancies worldwide. Despite the prevalence, it’s not always approached with the urgency it should be, knowing the critical role it plays in both fertility and pregnancy outcomes.
Iron needs increase significantly during pregnancy to support expanding blood volume, placental development, and fetal growth and development. Normal physiological changes in pregnancy can make it harder to maintain adequate levels. Ideally, we want to identify and address iron deficiency before pregnancy. Unfortunately, the solution isn’t as simple as supplementing everyone. Iron requires a more nuanced, individualized approach.
Let’s walk through how iron impacts fertility and pregnancy and what to consider when it comes to testing and supplementation.
Iron and Fertility
Iron status is typically assessed using ferritin, a marker of your iron stores. Low iron levels have been associated with both reduced fertility and higher miscarriage rates. When iron deficiency is present on lab work, correcting it (through supplementation) may help improve these outcomes.
When it comes to fertility, iron plays an important role in:
Ovulation: Hormone production and follicle development require adequate iron
Implantation: A well-prepared uterine environment depends on proper nutrient availability
Placental development: Critical for early pregnancy and nutrient transfer
Assessing iron is an important part of preconception care.
Iron and Pregnancy Outcomes
Iron requirements increase quite dramatically throughout pregnancy. This increase is, in part, due to increased iron requirements - pregnancy requires more iron for the expansion of blood to support both mom and baby, as well as the losses that occur in childbirth and additional needs for the placenta. The increase in plasma (the non-cell part of blood) volume happens to a greater extent than the actual blood cell mass. This creates an almost expected anemia and we adjust our thresholds depending on the trimester you are in. To meet the increased demands, intestinal iron absorption increases substantially by the third trimester. That said, even with the compensatory measures and lower thresholds, many women can’t meet the increased demands, especially if they entered pregnancy already deficient - which is also very common!
When it comes to pregnancy, even without overt anemia, iron deficiency can lead to symptoms such as fatigue, low mood, trouble concentrating, restless legs, shortness of breath. It also increases risk of preterm labour, postpartum hemorrhage, increased cesarean rates, higher rates of blood transfusions postpartum, higher infection rates, and longer hospital stays.
For the fetus, iron deficiency in mom increases risk of low birth weight, preterm birth, intrauterine growth restriction, and impaired neurodevelopment. Their brain development is particularly vulnerable to iron deficiency and the effects may last far beyond birth. Notably, newborns with iron deficiency often have impacted memory and processing speed, as well as impaired early bonding.
When Should You Test Your Iron?
If you’re trying to conceive, now is the time to check your iron levels.
Early identification gives us the opportunity to correct deficiencies before pregnancy, when demands increase significantly.
Testing typically includes:
Ferritin (iron storage)
Hemoglobin (to assess for anemia)
Other iron-related lab tests may also be performed, depending on your symptoms and health history.
These markers help guide whether supplementation is needed, and at what dose.
Testing throughout pregnancy is also important for monitoring how effective supplementation is and catching changes before birth.
Iron Supplementation is Not One-Size-Fits-All
Oral iron supplements are often a good starting point for most people. That said, they aren’t always the right choice for everyone.
Intravenous (IV) iron may be necessary for:
Moderate to severe deficiency (especially in the second or third trimester)
Poor response to oral supplementation
Significant side effects (e.g., digestive upset, nausea)
Malabsorption conditions
In these cases, IV iron can be a safe and effective way to restore levels more quickly.
Can You Take Too Much Iron?
Short answer: yes.
Iron is essential - it supports oxygen transport, energy production, and healthy pregnancy - but your body tightly regulates how much iron it absorbs. Though most pregnant (and many non-pregnant) people need iron, dosing does matter.
Iron regulation is controlled by a hormone called hepcidin, which acts like a gatekeeper:
Low iron: Hepcidin decreases → absorption increases
Adequate/high iron: Hepcidin increases → absorption decreases
When iron levels are already sufficient, taking high-dose supplements won’t necessarily improve your status. Very high doses of iron also trigger hepcidin - which is also why more isn’t always better. Excess iron can also contribute to oxidative stress, which may negatively impact tissues like the ovaries. This isn’t something to be alarmed about, but it does highlight the importance of testing and targeted treatment.
Key Takeaways
If you are iron deficient, correcting this may significantly improve fertility and pregnancy outcomes
If your iron levels are already optimal, additional supplementation is unlikely to help - and may actually be counterproductive
It’s recommended to test before supplementing, and get a dose prescribed by your provider.
If oral iron isn’t effective or tolerated, IV iron is a valuable alternative.
Iron is one of the most simple (and most impactful) nutrients to assess when it comes to fertility and pregnancy.
Understanding your levels allows us to treat you appropriately and monitor how effective that treatment is. Most pregnant folks end up needing iron at some point, but an individualized approach ensures we meet your needs.
Curious about supporting your body through conception to birth? I love working with those trying to conceive or who are already pregnant, navigating pregnancy, birth and beyond. You are welcome to book a complimentary meet and greet appointment to see if I’m the right provider to support you.