Abstract: Iron needs increase significantly during pregnancy, particularly in the third trimester. While many individuals can get adequate amounts of iron from diet alone, primarily those who consume meat consistently, others will have to supplement to keep up with increased demands. Since iron deficiency, particularly iron-deficiency anemia, are serious unwanted conditions causing harmful complications, iron supplementation should be utilized for those with inadequate iron biomarkers. Iron bisglycinate chelate is the ideal supplemental form for decreasing associated unwanted side effects and efficiently improving iron levels.
What is Iron? Why Do I Need It?
Iron is a critical mineral for red blood cell formation and energy-yielding metabolism. Cell growth requires iron, as iron creates two essential proteins, hemoglobin and myoglobin.
Hemoglobin is a protein found in red blood cells that carries oxygen from your lungs to the rest of your body. Hemoglobin prevents anemia and low energy by providing a consistent flow of oxygen to the brain, muscles, tissues, and cells.
Myoglobin is a protein that provides oxygen to muscles. As a component of myoglobin, iron can support muscle metabolism and healthy connective tissue.
Iron is also necessary for physical growth, neurological development, cellular functioning, and synthesis of some hormones. It is used to produce additional proteins and enzymes that contribute to respiration, energy metabolism, and proper immune function.
Dietary iron is absorbed in the small intestine and then transported throughout the body by binding to transferrin. The iron the body takes in spread among a variety of uses, with the majority of iron used for the production of red blood cell hemoglobin. The rest is stored in tissues in the form of ferritin. And a small minority is used to produce other functioning enzymes and proteins, including myoglobin. Hepcidin, a circulating peptide hormone, is the key regulator of both iron absorption and the distribution of iron throughout the body, including in plasma.
A deficiency in this critical mineral can be quite problematic. Iron deficiencies, whether as serious as anemia or not, can lead to various side effects. From an increased risk of child/maternal mortality to impaired exercise endurance, a lack of iron can lead to complications of varying degrees of severity. Iron deficiencies lead to neuropsychological effects, delayed cognitive development in children and adolescents, and decreased work productivity. Mild to moderate anemia may increase susceptibility to infectious disease.
Why Is Iron Important During Pregnancy?
Stages of growth and development, particularly pregnancy, rely on iron for support. During pregnancy, maternal red blood cell production dramatically increases to meet the placenta's and developing fetus's needs. Consequently, the amount of iron women need during pregnancy increases significantly, approximately 1.5 times. This increased need for iron is used for fetal and placental growth, the expansion of red blood cell mass, and roughly a quarter is lost in blood during a traditional birth. Iron necessity is lowest in the first trimester, and maternal iron stores are boosted initially due to the loss of menstruation. However, as the pregnancy progresses, the demand for iron increases, with demands greatest in the second and third trimesters.
Iron plays a key role in fetal development, which is why iron levels should be monitored and adjusted during pregnancy.
Preventing Iron Deficiency Anemia
Pregnant women are the most vulnerable group for iron deficiency. Even among non-vegetarians, it is estimated that only 20% of women have adequate iron stores for pregnancy. A National Health and Nutrition Examination Survey of data from 1999-2006 found that 18% of pregnant women in the United States had iron deficiency. Rates of deficiency grew as the trimesters progressed, showing 6.9% among women in the first trimester, 14.3% in the second trimester, and 29.7% in the third trimester. Iron deficiency is common during pregnancy, but it is easy to prevent by consistently checking your levels and adjusting your intake.
Since iron needs increase rapidly to provide for the developing baby, it's important to ensure you are not starting from a depleted state. However, iron stores and levels should be monitored throughout pregnancy, not just at your first prenatal visit, when iron levels will look their best. Iron deficiency anemia arises if stores become depleted and the body doesn't catch up properly in response to pregnancy demands. A drop in serum ferritin levels reflects an increase in blood volume and rapid utilization of the body's iron reserves, which can become depleted even in the absence of anemia.
Iron deficiency is problematic, regardless of pregnancy, but a lack of iron is particularly impactful when the body is developing a new baby. Inadequate iron intake during pregnancy is a risk factor for numerous complications, including preeclampsia, hypothyroidism, and preterm birth. It may also impair fetal brain development, stunt growth, and increase your baby's lifetime risk of obesity, diabetes, and high blood pressure.
There are varying stages of iron deficiency severity:
- Depletion of iron stores/mild deficiency: Serum ferritin concentrations decline. Symptoms are rarely noticeable or hard to distinguish from pregnancy symptoms. This stage can be easily rectified through an increased intake and understanding of your needs.
- Marginal iron deficiency: Iron stores are now depleted. Iron supply to red blood cells declines. Transferrin saturation, a transporter of iron, declines. Hemoglobin levels are usually within the normal range. Serum iron levels and total iron-binding capacity (TIBC) also show normal levels. However, hemoglobin and serum iron levels will decline as anemia approaches, and TIBC will begin to rise.
- Iron deficiency anemia: Iron stores are exhausted. Hematocrit and levels of hemoglobin decline. Microcytic anemia develops, characterized by small red blood cells with low hemoglobin concentrations or blood lacking adequate healthy red blood cells to carry enough oxygen to your body's tissues, resulting in noticeable symptoms and significant complications.
- Extreme Fatigue (beyond normal pregnancy fatigue)
- Overall Feeling of Weakness
- Headache, Dizziness, or Even Fainting Spells
- Shortness of Breath, Feeling Breathless
- Strange Cravings for NonFood Items
- Restless Leg Syndrome
If you've had two pregnancies very close together, experience extreme morning sickness and difficulty keeping food down, or are undernourished due to an eating disorder or very low weight, your risk of this harmful condition increases significantly.
Randomized controlled trials have shown that iron supplementation can be beneficial in preventing iron-deficiency anemia. However, we will discuss the pros and cons of supplementation later on in this article.
Am I Getting Iron From Food?
Yes! Food sources of iron are ideal. Nourishing food is free from abnormal unwanted side effects, and high-quality animal food sources are well-absorbed, providing plentiful amounts of iron. With animal food products, getting sufficient iron through diet alone is quite doable. However, vegan and vegetarian women will have a much harder time.
The best source of iron is liver and organ meats. However, as discussed during the vitamin A week, there are varying viewpoints on consuming liver during pregnancy, which should be considered before utilizing it for its iron-rich benefits. Incorporating small amounts of liver into home-cooked meatballs or other ground meat recipes could be a great way to get the high nutritional benefits of liver during pregnancy. Red meat, game meat, oysters, sardines, and dark meat poultry are also reliable iron sources, rich in heme iron.
One serving (3 oz) of the following foods include:
- Chicken liver 9.9 mg
- Oysters 5.7 mg
- Beef liver 5.6 mg
- Beef heart 5.4 mg
- Venison 3.8 mg
- Ground bison 2.7 mg
- Sardines 2.4 mg
- Ground beef 2.3 mg
- Clams 2.3 mg
- Lamb 1.7 mg
- Ground turkey 1.7 mg
- Chicken thighs 1.2 mg
- Chicken breast 0.9 mg
- Wild salmon 0.5 mg
Vegetarian sources of iron, or non-heme iron, can be found in many foods in high amounts. However, the amount the body can absorb and utilize is much lower and easily influenced.
The amounts in the following sources, before bioavailability considerations are:
- Fortified Breakfast Cereal (1 serving) 18 mg*
- Spinach (½ cup boiled) 3 mg
- Tofu (½ cup) 3 mg
- Lentils (½ cup) 3 mg
- Chickpeas (½ cup) 2 mg
- Baked Potato with Skin 2 mg
- Cashew Nuts (1 oz) 2 mg
* Iron absorption from whole-grain cereal is low at only 0.3% to 1.8% due to the presence of fiber, or phytic acid, and other anti-nutrients that interfere with absorption. The iron found in cereal is also fortified with synthetic iron. This type of iron can cause digestive discomfort in some individuals.
Even though non-heme iron absorption is poor (2-13%), it can be enhanced through food combining techniques and cooking practices.
Heme vs. NonHeme Iron: Bioavailability Matters
The bioavailability of a nutrient dictates how well your body absorbs and utilizes that nutrient. Bioavailability is critical for iron, and there is a great difference in bioavailability depending on whether the iron is heme or non-heme.
Dietary heme iron is derived primarily from hemoglobin and myoglobin in meat and is absorbed in the intestinal cells intact. It is then metabolized by a heme oxygenase enzyme and transferred to the bloodstream for transport, together with other iron taken up by the cells. Heme iron is highly bioavailable (20-25%) and is relatively unaffected by dietary factors.
Non-heme iron, derived from vegetarian food sources, is solubilized and transferred into a common pool of non-heme iron located in the lumen of the upper gastrointestinal tract. The absorption rate of this non-heme iron pool is greatly affected by the presence of ligands in undigested or partially digested foods, which either enhances or inhibits absorption. Vitamin C, ascorbic acid, enhances the absorption of non-heme iron, while phytate, polyphenols, and calcium supplements hinder absorption. If insoluble forms of iron get digested, they are excreted and not absorbed.
You can enhance iron absorption, particularly of the non-heme variety, from your diet in the following ways:
- Consume iron-rich foods along with a source of vitamin C or other acidic ingredients, such as a vinegar-based salad dressing, tomato sauce, or a lemon squeeze. Lentils with red bell peppers are a good idea, as well as incorporating vitamin C-rich fruits into your vegetarian meals. Strawberries, oranges, papayas, and kiwis are all very rich in vitamin C.
- Consider cooking in cast iron pans, which can increase iron content post-cooking. Eggs and potatoes averaged a five-fold increase in iron content after cooking in cast iron.
Unfortunately, the phytic acid and fiber found in most plant foods make the non-heme iron found in these foods harder to absorb. Oxalic acid found in high amounts in spinach and rhubarb works similarly, disrupting the absorption of the iron found in these foods. Caffeine, found in coffee and tea, can also block iron absorption. Calcium, zinc, magnesium, and copper compete with iron for absorption. Calcium is the most prominent absorption competitor as iron-rich meals should not be consumed alongside calcium supplements or antacids. Even herbs such as chamomile, peppermint, feverfew, and St John's wort can lower your iron absorption rate, which may be something to consider if you are an avid tea drinker.
Do I Need An Iron Supplement? What Form of Iron Is Best?
When deciding whether an iron supplement is right for you, there are three main things to consider:
- What are my iron levels?
- How rich is my diet with heme iron?
- What form of iron supplementation am I using?
Iron needs and tolerance vary significantly by individual. And the amount of iron your body requires changes throughout the pregnancy. While iron supplementation is proven to increase iron stores in the body and combat the onset of iron deficiency anemia, supplementation should be responsive to individual iron monitoring and testing. Iron is very important, particularly during pregnancy; however, supplementation can come with unwanted side effects, such as constipation and other gastrointestinal issues like nausea, vomiting, and diarrhea. If iron supplements prevent food from staying down, you are putting your body at risk for other nutrient deficiencies. Research also shows that taking iron supplements during pregnancy if you're not iron deficient can increase your risk of gestational diabetes and preeclampsia, thus putting you and your baby at risk for short and long-term complications.
Thus, it is highly beneficial to match intake to individual levels. Some prenatal specialty companies think it is best to supplement with iron separately. In this manner, iron supplementation doses can be tweaked according to actual needs instead of standardized and lumped in with other essential nutrients as part of the prenatal vitamin. Furthermore, an extensive review of studies revealed that iron supplementation during pregnancy did not lead to any added health benefits for women who already had adequate iron levels. With these points in mind, why would you risk side effects if supplementation isn't necessary?
These recommendations can be reflected upon in comparison to the following government institutions and societies' formal stances on iron supplementation to make the most suitable decision for you.
- The American College of Obstetricians and Gynecologists (ACOG) states that high-quality and consistent evidence shows that iron supplementation decreases the prevalence of maternal anemia at delivery. ACOG recommends screening all pregnant women for anemia and treating those with iron deficiency anemia with supplemental iron in addition to prenatal vitamins.
- The Centers for Disease Control and Prevention (CDC) recommends that all pregnant women take a low oral dose (30 mg/day) of supplemental iron and be screened for anemia. Women with iron deficiency anemia should be treated with an oral dose of 60-120 mg/day of iron.
- The U.S. Preventive Services Task Force concluded that there is insufficient evidence to recommend for or against both screening for iron deficiency anemia in pregnant women and routinely supplementing them with iron to prevent adverse maternal health and birth outcomes.
- The Institute of Medicine states that since the median intake of dietary iron is well below the EAR, pregnant women need iron supplementation.
- The Dietary Guidelines for Americans advise that pregnant women take an iron supplement when recommended by a doctor.
The form of supplementation is also important. Ferrous fumarate or ferrous sulfate are the most commonly prescribed forms of iron. However, they are also the most difficult to tolerate. The increased risk for unwanted side effects in these forms causes lower efficacy of preventing iron deficiency, as adherence to supplementation is significantly lower in those experiencing side effects.
Iron bisglycinate is a well-absorbed form of supplemental iron. Iron bisglycinate chelate (Ferrochel) is the most bioavailable form on the market, 4-7 times greater than that of ferrous sulfate, and is non-constipating. It can also be consumed with food without altering its bioavailability. Ferrochel has been widely tested in Brazil since the country has implemented a mandatory iron supplementation program within their food industry to encourage the elimination of iron deficiency anemia. This form has shown to have superior effects on biomarkers at a lower dose than any other alternative iron form.
To dive deeper into the ferrous glycinate form - it is an iron (II) chelate with the amino acid glycine that also contains citric acid. The exact form of the substance restricts reaction with dietary inhibitors of iron absorption, neutralizes ferrous iron, and protects gastrointestinal surfaces from irritation by the iron. This structure makes ferrous glycinate an ideal fortificant for foods with high absorption inhibitor content, such as phytates.
Like other non-heme iron compounds, ferrous glycinate is absorbed according to the body's iron status. If stores are low, more is absorbed. If stores are high, less is absorbed. Additionally, as with other non-heme iron compounds, the nature of the other foods consumed with ferrous glycinate may affect the bioavailability. Results of research studies have shown that dietary supplementation and fortification of ferrous glycinate at doses of up to 60 mg of iron per day corrected iron status in individuals with iron deficiency while showing no gastric side effects. There also isn't any evidence that the administration of iron in the form of ferrous glycinate will increase stores of iron after the nutritional requirement for iron has been satisfied.
Iron Supplementation in the Third Trimester
As discussed earlier, iron demands grow as the pregnancy progresses, and the appropriateness of supplementation may differ from trimester to trimester. Although iron supplementation in the first and second trimesters may not be necessary for you, that could change by the third trimester. It may be appropriate to introduce a supplement if you're finding it hard to maintain an adequate intake of iron-rich foods or if you're iron-deficient or anemic. During the third trimester, your baby is pulling iron from your diet and body stores for the first six months of life. It is also important to ward off postpartum anemia during this time. Postpartum anemia can occur from continued inadequate iron intake during pregnancy as well as blood loss experienced during delivery. This condition in moms is linked to depression, anxiety & stress, cognitive impairment, stilted mother-infant attachment, and infant developmental delays.
Alternative Forms of Supplementation
Desiccated Liver Supplements: Liver is a rich source of essential nutrients, including vitamin A, B12, folate, iron, zinc, and copper, and can be a safe and effective way to increase iron intake. Although there is a long history of use, formal studies on the supplements are limited.
Spirulina: A type of algae that has been studied for its effects on iron markers. A study that supplemented pregnant women with either spirulina (1500 mg per day) or iron combined with folic acid found that the spirulina supplement showed a significantly higher gain in hemoglobin than its iron counterpart.
How Much Do I Need?
The official RDA for iron is 27 mg per day in pregnancy, compared to 18 mg per day in non-pregnant women. Due to the differences in bioavailability between meat and vegetarian food sources, the RDA for iron is 1.8x higher for vegetarians.
Lastly, the Tolerable Upper Limit is set at 45 mg daily. Physicians sometimes prescribe intakes higher than the upper limit to replenish iron stores for individuals with iron deficiency anemia.
We can provide the official RDAs for iron but ultimately, the amount of iron you need is based on your unique makeup and iron test results.
How Do I Know If I Am Getting Enough Iron?
Transferrin takes unbound iron deposited in our organs and puts it in a red blood cell protein called ferritin. Serum ferritin reflects iron body stores and is not affected by recent iron ingestion, making serum ferritin concentration the most efficient and cost-effective test for diagnosing iron deficiency. Since serum ferritin decreases during the first stage of iron depletion, it allows for early detection of low iron before developing iron-deficiency anemia. However, ferritin responds to inflammation, infection, and other disease states, and under these conditions, it is not an accurate reflection of iron stores. Ferritin levels can be falsely normal or elevated, despite the presence of anemia. Besides using additional iron markers to get a complete picture of iron levels, an evaluation of the c-reactive protein (CRP) marker can assist in obtaining the correct diagnosis. If CRP is elevated, indicating inflammation, re-evaluation of the serum ferritin level is recommended after inflammation has normalized.
Hemoglobin, the protein that carries oxygen around the circulatory system, is also considered a functional marker of iron status. Since other nutrient deficiencies besides iron can cause anemia, hemoglobin measurements should be used alongside other iron biomarkers, such as serum ferritin. Hematocrit and hemoglobin are the most popular tests for iron; however, they are not as indicative of iron status as ferritin.
Total iron-binding capacity (TIBC) is an additional marker that measures the amount of iron proteins can bind in the blood. Lastly, an increased transferrin receptor (sTfR) concentration in serum (or plasma) is an early sign of iron deficiency and an indicator of the severity of the insufficiency. This marker will elevate when the body senses it is depleted in iron, indicating transferrin is working hard to search for and attract more iron and saturating more of the iron receptor reserves. sTfR is less affected than serum ferritin by an inflammatory state, and body iron stores can be further estimated by calculating the ratio of sTfR to SF.
Elevated total iron-binding capacity (TIBC), low serum iron level, and a low serum ferritin concentration are diagnostic for iron deficiency.
Prenatal Vitamin Brands: What's the Iron Amount and Type in Popular Prenatal Brands?
|Name of the Prenatal||Amount||Type|
|Parsley Health Prenatal:||30 mg||(ferrous bisglycinate chelate)|
|Modern Fertility Prenatal:||18 mg||ferrous bisglycinate)|
|Ritual Prenatal:||18 mg||(ferrous bisglycinate)|
|Perelel: Conception Support and All Trimesters Pack:||15 mg||(ferrous bis-glycinate chelate (Ferrochel))|
|NatureMade Prenatal Multi + DHA:||27 mg||(ferrous fumarate)|
|Seeking Health: Optimal Prenatal:||N/A||N/A|
|Designs for Health: Prenatal Pro:||27 mg||(Ferrochel ferrous bisglycinate chelate)|
*FullWell does not include iron in their prenatal supplement because needs and tolerance vary significantly by individual. It may be best to match the form and dose of iron to your specific needs. FullWell suggests monitoring iron status with a healthcare practitioner and taking it separately in appropriate doses if you need supplemental iron. This will help avoid unnecessary digestive distress from iron supplementation and prevent consuming too much or too little iron.
**Optimal Prenatal does not include iron because some women do not process iron well or do not need iron supplementation.
Precision in iron supplementation during pregnancy is highly beneficial and worth the extra effort in individual testing and curation of dose. With that in mind, if you get sufficient amounts from food or want to supplement with it separately to have more control over the amount, avoiding iron in your prenatal vitamin may be worthwhile. The form is also very important when evaluating iron supplementation. All of the above companies, besides NatureMade, use the best form, iron bisglycinate.
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- 8 Things to Know About Iron + Pregnancy. FullWell. Accessed June 23, 2022. https://fullwellfertility.com/blogs/blog/8-things-to-know-about-iron-pregnancy
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- Niang K, Faye A, Tine J, et al. Spirulina Supplementation in Pregnant Women in the Dakar Region (Senegal). Open J Obstet Gynecol. 2017;07:147-154. doi:10.4236/ojog.2017.71016