8 Things to Know About Iron + Pregnancy

8 Things to Know About Iron + Pregnancy

ayla barmmer

Iron is one of the most popular topics I am consistently addressing via email and DM.

And with good reason! Iron is a critical mineral needed for growth and development. Iron levels should be monitored and adjusted while trying to conceive and during pregnancy: you and your developing baby depend on it.

That said, the number one question I receive has to do with the fact that FullWell Prenatal, well, doesn't contain any iron.

Really?! Why

FullWell Prenatal does not have iron in it by design. Let me explain.

Iron needs and tolerance vary significantly by individual. The amount of iron your body requires changes as a pregnancy progresses, and getting enough iron is critical for health at every stage. However, not all women will need to supplement with iron to keep their levels in an ideal range. Plenty of women get enough iron through diet alone (which makes me - the real food dietitian - extremely happy! More on that later). For those who need to supplement, it may be best to match the form and dose of iron to individualized, specific needs. In my experience, I’ve learned that monitoring your iron status with your healthcare practitioner will always be your best bet, as form and dosage are much more unique to each individual. This way, if you do need supplemental iron, you’ll know specifically which form to take and most likely be consuming it separately in appropriate doses at your healthcare practitioner’s recommendation. This will help avoid unnecessary digestive distress, avoid interfering with the absorption of other vital nutrients and keep you from consuming too much or too little iron overall. 

So, I didn’t leave iron out of FullWell Prenatal because it’s unimportant. I left it out because it’s so important it should be tended to on its own, apart from your (equally important) comprehensive prenatal multivitamin.

Iron is such a big deal that it gets its own blog post! Read on to learn more about:

  1. What iron is, and what it does in the body
  2. Which real foods are highest in iron 
  3. Who is at risk for iron deficiency
  4. Why iron is so important during pregnancy
  5. How iron needs change and continue to evolve once you become pregnant
  6. How I carry out specific iron recommendations within my private practice
  7. Which labs to ask for when assessing your iron needs with your healthcare provider
  8. What to look for in an iron supplement

We’ve got a lot to cover, so let’s start at the beginning. 

1. What is iron, and why is it so important?

A basic, general understanding of the importance of iron in the human body dates back to ancient times. Some evidence suggests that advanced civilizations such as the Egyptians, Hindus, Greeks, and Romans used iron for medicinal purposes to treat symptoms that were a result of (or resembled a consequence of) iron deficiency. Not bad, early science! But don’t worry: the research we base our current recommendations and further exploration on did not begin until the mid-twentieth century and, as you’ll see in this post, is still ongoing and constantly updated.

Today, we know that iron is a mineral that your body needs for cell growth and development.

Most importantly, iron is used to create

  • Hemoglobin, a protein found in red blood cells that carries oxygen from your lungs to the rest of your body
  • Myoglobin, a protein that provides oxygen to muscles

Iron is usually absorbed from food in your small intestine and transported throughout the body by binding to transferrin, a protein that originates in your liver. 70% of that iron is incorporated into red blood cell hemoglobin production and can be found in your blood and muscles. The rest is stored in tissues in the forms of ferritin or hemosiderin, with additional amounts utilized to produce other proteins, such as myoglobin and certain enzymes. A smaller portion forms proteins designed for respiration, energy metabolism, and proper immune function. The average non-pregnant adult woman holds about 300mg of stored iron in her body (which, in context, is enough to last for about six months). 

Now, not all of us fall into that “average” category. The National Institutes of Health recommends roughly 18 mg of iron per day for non-pregnant women and 27 mg per day for pregnant women. Deficiency - even before pregnancy - is not uncommon for a variety of reasons, one of them being diet. Many women adhere to specific diets that naturally lack sufficient iron, putting them at a much greater risk for iron deficiency.

I’ve already hinted at it (and will repeat it before the end of this post), but the best way to ensure your iron intake is adequate is through food.

2. Which real foods are highest in iron?

I discuss this term as it pertains to supplements, but it also applies to real food: When it comes to getting nutrients through food, bioavailability matters. Remember, all I mean when I use the term “bioavailable” is how well your body absorbs and utilizes a nutrient.

high bioavailability = very easily/quickly absorbed
low bioavailability = not as efficient

There are two main types of iron that you can acquire through diet.

  1. heme iron, which is found in high quantities in animal proteins and is highly bioavailable (about 25-40%)
  2. nonheme iron, found in plants, holds a much lower absorption rate (2-13%). Nonheme iron is more challenging for your body to absorb, which means it also physically takes longer before your body can put it to work

For women who eat animal products and byproducts, it is pretty doable to get the amount of iron you need through diet alone. The foods richest in iron are staples in a western diet.

iron foodsFor vegan and vegetarian women, however, it’s a bit tricker. Many plant-based whole foods contain iron, but remember, these will all be in the nonheme form.

iron foods

When it comes down to animals vs. plants, the issue lies with bioavailability. To get the amount of iron you need even before pregnancy without consuming meat, you’d have to eat truly enormous volumes of these foods even to have a shot at absorbing enough iron. And while many foods, like cereals, are fortified with iron, it is understood that this iron is not only very poorly absorbed but often leads to digestive discomfort, which we are trying to avoid at all costs!

One thing that can help plant-sourced nonheme iron become more bioavailable is to eat it with another food that is high in vitamin C (e.g., bell peppers, citrus, strawberries, tomatoes, etc.). Vitamin C - or ascorbic acid - has been shown to enhance the absorption of nonheme iron in foods. But it is also important to note that any vitamin C-rich foods fortified with calcium (like many orange juices) should be avoided while pairing your food, as calcium inhibits iron absorption. There are a handful of additional compounds that can also inhibit iron absorption, including

    • Phytates, a compound present in most grains
    • Oxalic acid, which is found in high amounts in spinach and rhubarb
    • Polyphenols, specifically polyphenols found in coffee and chocolate 

Plant-based eaters are on my shortlist for people who might need to consider supplementation. As you read on, you’ll discover how to talk to your healthcare practitioner about thoroughly testing your iron through lab work and decide what kind of supplementation is best for you.

3. Could I be at risk for iron deficiency?

Diet aside, before you become pregnant, iron loss through substantial bleeding (e.g., heavy menstrual periods) is one of the most common causes of iron deficiency in women. Significant blood loss can lead to iron deficiency, so if you tend to have intense periods pre-conception, it might be a sign that you need to up your iron-rich food intake and consider supplementing. 

Some who suffer from chronic gastrointestinal disorders such as celiac or inflammatory bowel disease can also quickly become iron-deficient (and even deficient in a whole host of nutrients) due to decreased absorption through the digestive tract. This also applies to people who have undergone bariatric procedures, especially gastric bypass operations.

While it’s not ideal, mild iron deficiency isn’t as scary as it sounds. Once you know and understand your needs, there are ample ways to rectify your lack of the nutrient. The real thing to be concerned about is iron deficiency anemia, a condition you become more susceptible to when you are iron deficient. This is a condition when your blood lacks ample healthy red blood cells to carry enough oxygen to your body's tissues, which is a big problem.

You might be suffering from iron deficiency anemia if you experience any of the following symptoms: 

  1. Extreme fatigue or a general feeling of weakness
  2. Chest pain, erratic heartbeat, shortness of breath
  3. Headache or dizziness
  4. Poor appetite

4. Why is iron so important before, during, and after pregnancy?


The absolute best time to evaluate your iron status is before you even start trying to conceive so that you have a chance to get ahead of the game! While trying to conceive, you should be aware of your iron intake through food and consider taking additional steps with your doctor if your lab results show room for improvement. This is the most straightforward stage to fix iron levels while on your pregnancy journey, as the stakes are relatively low (barring you suffering from any severe symptoms of iron deficiency or anemia). Working with your healthcare provider to get your levels within range is the first and most productive step you can take.

While pregnant

During pregnancy, you need a significantly more significant amount of iron than non-pregnant women because the amount of blood in your body increases to provide for yourself and your baby. You’ve got to have enough to make more blood in your own body that will go on to supply oxygen to your baby as they develop. 

This is why starting from a depleted state is not ideal. Your needs increase so rapidly to begin providing for baby that you can quickly run through your stores and still have trouble catching up and getting enough iron during pregnancy, which could lead to iron deficiency anemia. If untreated, this could result in low birth weight, premature birth, decreased milk production, and low levels of iron into infancy which could ultimately affect your baby’s brain development.


Postpartum anemia usually results from 1) being iron deficient before becoming pregnant, 2) continued inadequate iron intake during pregnancy, and 3) the blood loss experienced during delivery. This triple whammy produces the exact combination of circumstances that lead to postpartum anemia, which has been associated with

  • depression
  • anxiety & stress
  • cognitive impairment
  • stilted mother-infant attachment
  • infant developmental delays 

5. Will my iron needs change once I become pregnant? 

Boy, will they ever!

It’s never a bad idea to work to understand normal reference ranges and laboratory values to look for during pregnancy, predominantly because those ranges and values will change from conception into pregnancy and then continue to change through each trimester. There’s a lot to keep track of.

The physiological iron demand in pregnant women increases throughout gestation. Roughly a third of the iron you consume will be put toward fetal and placental growth, about half will contribute to the expansion in red blood cell mass, and a quarter will be lost in blood at delivery in a traditional birth. A lower iron necessity in the first trimester fluctuates significantly into your second and third trimesters, respectively.

As baby develops, your needs will change from trimester to trimester, and it isn’t always as easy as generally needing more as you go. Getting specific with your doctor will be extremely helpful.

6. How do you address iron concerns in your private practice?

I look at the big picture first and then dive in deeper to find the root cause of the issue. Iron can be affected by many different variables, and many things must fall into place before iron can be absorbed. A healthy digestive system is critical, as are adequate amounts of specific enzymes, hormones, and proteins that bind with and transport nutrients into the bloodstream. 

This might surprise you, but stomach acid is important when it comes to iron. Over-the-counter medications such as antacids and acid blockers can lead to malabsorption. If you experience any heartburn or reflux, speak with your healthcare practitioner about how to treat it to ensure you maintain your gut health. Iron supplementation can also interfere with the absorption of Levothyroxine and other thyroid prescriptions, so if you are on thyroid medication, it’s best not to take it within four hours of iron supplements.

It’s all in the timing.

Timing plays into iron absorption. As I mentioned above, calcium can interfere with iron absorption, even in more bioavailable forms, such as dicalcium malate (the form of calcium I formulated into FullWell Prenatal). I always have my private practice clients stagger prenatal vitamins with iron supplements to allow them more time and a better chance of being digested and absorbed correctly for optimal results. Also note that many women taking high doses of iron supplements on an empty stomach can experience upset stomachs, constipation, nausea, abdominal pain, vomiting, and fainting, so it’s not out of the question to take an iron supplement with food. 

If I haven’t stressed this enough, let me tell you again.

Your diet is the best way to ensure you get the iron you need. This means I always analyze what foods my private practice clients typically eat and take note of how and when they are eating them to ensure the most iron-rich foods have the best shot at efficient absorption. 

Finally, I work with my clients and their healthcare providers to ensure that all of their labs are ordered and interpreted correctly. This can be a tricky subject as the labs required to understand how much iron you are absorbing can get confusing, but bear with me. I’m going to lay it all out for you.

This is the part you’ve all been waiting for!

7. Which labs do I need to ask to assess my iron levels accurately?

I love that many of you reach out with specific questions about lab work! Knowing what you don’t know and continuing to advocate for yourself and your baby by asking questions is such an admirable quality. I’m preaching to the choir when I tell you that while your doctor is probably fantastic, it never hurts to be informed and involved in lab work. After all, it’s your body and your baby! 

Before I get into specific labs, let’s explore what we’re looking at/for.

Let’s talk about ferritin.

When we consume and absorb too much iron, it’s not like a water-soluble vitamin like B12 that we can excrete. Instead, our body employs a safety guard to protect us from overdoing it. When we have too much unbound iron deposited in our organs, that transferrin we glossed over a little earlier grabs it and puts it in a red blood cell protein called ferritin.

Ferritin is like a safe storage of excess iron. If you don’t have any excess iron, there’s nothing to store. So, when we don’t eat enough iron, our body senses that it doesn’t have the iron it needs and sends a signal to ferritin, which naturally releases stored iron for us to use.

But even with ferritin acting as our iron safe, when your body senses that it doesn’t have enough iron, it essentially begins to ration what you’re storing, shutting off iron channels to the processes it deems least critical. This is when we start experiencing problems like hair loss. Your body makes the call that sending iron to your integumentary system is less critical than getting it to your bone marrow and employing it to create more red blood cells. 

So when it comes to your lab work, ferritin is the most accurate test and most specific indicator of iron status overall.

Since ferritin is the primary storage form of iron, it’s the simplest way to catch low iron early. It is used to determine iron deficiency when the body is without the presence of inflammation, fatty liver disease, obesity, hyperthyroidism, or any malignancies. 

Low ferritin is a red flag, but too much isn’t good, either. In the presence of inflammatory processes or chronic diseases, ferritin levels can be falsely normal or elevated, despite anemia. This is because ferritin reacts as an acute-phase protein. Evaluating C-reactive protein (CRP) levels may assist in obtaining the correct diagnosis, excluding infections or inflammation. If the CRP value is elevated, re-evaluation of the serum ferritin level is recommended after the normalization of CRP concentration.  

Now let’s go back to hemoglobin and hematocrit.

The most common lab-ordered test for iron involves looking for hemoglobin and hematocrit. These are not as indicative as ferritin, yet hemoglobin and hematocrit are primarily the only tests ordered in conventional medicine. In my experience, these tests are not a sensitive or specific enough indication of iron status, though they can serve as a good marker of improvement over time.

Remember transferrin?

Transferrin is the transporter of iron, receiving it from the absorption stage and ensuring it gets to where it needs to go. 

If your ferritin levels are normal, a serum transferrin value < 15% proves a latent iron deficiency because more iron is released from blood circulation by transferrin to ensure erythropoiesis (or the production of red blood cells). 

Next up is TIBC.

TIBC stands for transferrin iron binding capacity

This lab value will tell us how prepared your body is to take in and utilize iron. TICB values are high when your body senses it is depleted in iron since it’s going out of its way to try to do what it can to fix that iron deficiency.

Transferrin has a high affinity to iron, which means it’s got a strong attraction to it, almost like a magnet. Its job is to look for unbound iron and bind to it so that it safely transports it to where it needs to go.

Then, we’ll want to look at % saturation.

This will measure the percentage saturation of transferrin with iron, calculated by dividing the serum iron concentration by the total iron binding capacity (TIBC) and multiplying by 100. 

Another helpful parameter to detect iron deficiency during pregnancy, especially in the case of normal ferritin values and elevated CRP, is transferrin receptor (sTfR). sTfR will present with an increase in cases of iron deficiency or greater iron cellular demand. During pregnancy, increased sTfR values are related to increased erythropoiesis stimulation—an additional major iron requirement resulting from demands on the body by iron-dependent cell proliferation. sTfR concentration is an excellent marker to keep checking in on because infections or inflammatory reactions do not influence it, so you and your doctor can take it at face value.

Now, a comprehensive iron panel includes the following:

  • Serum iron test — measures the level of iron in the liquid portion of your blood
  • Transferrin test — directly measures the level of transferrin in the blood, which is the protein that transports iron around in the body. Under normal conditions, transferrin is typically one-third saturated with iron. This means that about two-thirds of its capacity is held in reserve.
  • TIBC (total iron-binding capacity) — measures the total amount of iron that proteins can bind in the blood. Since transferrin is the primary iron-binding protein, the TIBC test is a good indirect measurement of transferrin availability.
  • UIBC (unsaturated iron-binding capacity) — a UIBC test determines the reserve capacity of transferrin, i.e., the portion of transferrin that has not yet been saturated with iron. UIBC also reflects transferrin levels.
  • Transferrin saturation — a calculation that reflects the percentage of transferrin saturated with iron (100 x serum iron/TIBC).
  • Serum ferritin — reflects the total amount of stored iron in the body. 
  • C-reactive protein (CRP) — if ferritin is normal, but HgB and HcT are low, this measurement can help determine what role inflammation may be playing

One thing to note about iron deficiency anemia

Good news and bad news: Iron deficiency anemia comes on gradually.

This is good news because it means once you know whether or not you are deficient, you have time to correct it. It’s bad news because unless you’ve run your labs, you might not even realize you are at risk.

When your rate of iron loss exceeds the amount of iron you absorb from food or supplement intake, iron stores are slowly used up. At this stage, ferritin will be low, but serum iron and TIBC will usually look normal while you are still not entirely dipping into the anemic range. As the iron deficiency worsens, serum iron levels fall, TIBC and transferrin rise, and anemia develops. Then, with prolonged or severe iron deficiency, the red cells become small and pale due to decreased hemoglobin levels, and the other symptoms we’ve discussed might begin to take center stage.

Stay on top of your labs so that you can be well-informed enough to make the right decisions, and you will be just fine!

8. If I have to supplement, what are the best ways to find the right one?

Once your lab results come back, your healthcare practitioner will help you determine what is right for you, depending on your pregnancy stage. I cannot stress enough how important it is to work within the trimester-specific lab reference ranges I discussed above when evaluating iron status and looking at the right markers. Hemoglobin and hematocrit (two markers on a standard CBC) are insufficient. You’ll need to know ferritin at a minimum, but running a full list of a complete panel will be more informative, especially near the end of your pregnancy. 

iron fullwell fertility


In most cases, a 25mg daily dose of iron bisglycinate has been shown to be as effective in preventing iron deficiency and iron deficiency anemia in pregnancy as the more common (but more difficult to tolerate) form of iron, ferrous sulfate

  • Iron bisglycinate 25mg (elemental iron) once to twice daily
  • Herbal Iron Tonic Syrup may help reduce the need for other iron supplements and is generally the easiest to tolerate. It simply requires procuring herbs and some at-home preparation. Taking in addition to iron bisglycinate may support better motility (e.g., less constipation, more regular bowel movements), absorption, and improve overall tolerance of the iron bisglycinate. 

herbal iron tonic

herbal iron tonic

Add yellow dock, dandelion, rose hips, ginger, cinnamon, anise, and 4 cups of water to a pot. Heat on low and simmer for 30 minutes to an hour, uncovered, stirring occasionally. Turn off the heat and immediately add nettles and molasses. Let steep, covered for 1 hour or more. Strain and discard solids. Stir in fresh orange juice and store refrigerated for up to 2 weeks. Dose with 1-2 tablespoons per day.

Do you have more questions about iron? Always feel free to reach out to hello@fullwellfertility.com.

*The information on this website is provided for educational purposes only and should not be treated as medical advice. FullWell makes no guarantees regarding the information provided or how products may work for any individual. If you suffer from a health condition, you should consult your health care practitioner for medical advice before introducing any new products into your health care regimen. For more information, please read our terms and conditions.


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