Nourishing your body with a healthy diet is always important, but even more so when you're eating for two. Although your baby needs a steady stream of vitamins and minerals in the womb, your own nutrient needs increase significantly as your body performs the work of pregnancy.1 And making sure your body has the right amount of iron – a mineral essential to red blood cell production – is a must.

Without an iron boost in your diet, you could be at risk of anemia, which is the condition of not having enough healthy red blood cells to carry oxygen to your body's tissues. Anemia makes you feel tired and weak at any stage of your life, but during pregnancy it can have many effects – and some of them might surprise you.

A low iron level, also called iron deficiency, is the cause of most cases of anemia during pregnancy.2,3

How iron delivers oxygen to you and your baby

Iron has an essential role in the formation of new red blood cells, which contain hemoglobin, the iron-rich protein that gives blood its red color. Hemoglobin enables red blood cells to carry oxygen from the lungs to the tissues throughout your body – and, when you're pregnant, to your developing baby.

To keep up with your body’s oxygen demand during pregnancy, you need 20-30 percent more red blood cells than you had before you were pregnant.2 But to form these red blood cells the body's need for iron increases dramatically.4-6

Some women have enough iron reserves built up to meet their own needs, as well as their baby's, if they stick with a healthy diet. But many women don't. As your pregnancy progresses and your body uses up more stored iron, you could be at risk for low iron. According to the World Health Organization, 37 percent of pregnant women worldwide have anemia.3

Personal factors can predict your iron supply

Just being pregnant increases your risk of iron deficiency. But your risk is especially high if your iron stores are already low or depleted for other reasons, such as:2,5,6

  • Getting pregnant during adolescence
  • Getting pregnant soon after a previous pregnancy
  • Being pregnant with multiple fetuses
  • Vomiting because of morning sickness
  • Having a history of heavy periods
  • Having a history of anemia
  • Eating a diet that is low in iron (especially being vegetarian or vegan)
  • Having bariatric (weight loss) surgery, such as gastric bypass, gastric banding, or sleeve gastrectomy

Whether or not you have known risk factors for anemia, your health-care professional likely will order a blood test to screen for this condition at your first prenatal visit. The results of this test will show how well your body has processed and stored iron historically, and how carefully you may need to be watched for changes as your pregnancy progresses.

The dangers of deficient iron during pregnancy

Mild anemia isn't likely to cause any health issues for you or your baby. But more severe anemia can be dangerous for both of you.1-3,5,6

Severe anemia will put your baby at risk of: 1-3,5-6 

  • Being born too early (premature birth)
  • Being born at a low birth weight
  • Developing anemia in infancy
  • Being stillborn (dying before birth)

As for the mother, severe anemia will put you at risk of:

  • Making it more difficult to fight infections
  • Losing too much blood during delivery
  • Having restless legs syndrome during pregnancy4
  • Developing postpartum depression

Signs and symptoms of anemia

Based solely on how you feel, it can be hard to recognize mild anemia during pregnancy. Many signs and symptoms are sneaky because they seem like normal pregnancy changes. But if mildly low iron becomes severely low, then anemia’s signs and symptoms are more obvious:2-6 

  • Fatigue and weakness
  • Pale or yellowish skin
  • Rapid or irregular heartbeat
  • Chest pain
  • Feeling lightheaded or dizzy
  • Cold hands and feet
  • Headache
  • Shortness of breath
  • Trouble concentrating

Dietary choices that increase your iron intake

Getting enough iron before you are pregnant helps prevent anemia during pregnancy. That is one of the reasons why health-care professionals recommend taking a prenatal vitamin before a woman conceives – ideally, on a daily basis during her reproductive years.7

In addition, make sure your regular diet includes plenty of iron-rich foods. Animal protein, including lean meats, poultry, and fish, provide a type of dietary iron called heme – the type of iron your body absorbs and utilizes most easily.

Many plant-based foods are good sources of non-heme iron. Some of the best choices to meet your iron needs include: 

  • Dried fruits, such as raisins and apricots
  • Dried beans
  • Peas
  • Dark green leafy vegetables
  • Eggs
  • Peanuts
  • Iron-fortified foods, such as certain cereals, breads, and pastas

To enhance your body's absorption of iron, drink orange or other citrus juices or eat foods rich in vitamin C at the same time you eat high-iron foods.1,6-8 

When foods don't fulfill your iron needs

Pregnant women need at least 27 mg of iron each day.1,2,6-8 Your prenatal vitamin should provide this, unless you’re taking a gummy prenatal vitamin, which generally does not contain iron. In this case, your health-care professional may recommend an iron supplement. 

If blood tests early in your pregnancy are normal, then you might not need more iron than what's included in your diet and your daily prenatal vitamin. If your blood tests show that you have low iron, then your health-care professional will likely recommend an iron supplement. The amount of additional iron you need will depend on how much iron is in your prenatal vitamin, what your current iron level is, and what form of iron is prescribed. Some forms of iron are better absorbed than others. 

Taking antacids or calcium supplements can interfere with iron absorption, so if you use these, then take them at a different time than your iron supplement.3,6,8,9 And space your dose of iron at least 1-2 hours apart from foods that can block iron absorption:  cheese, yogurt, eggs, milk, spinach, tea or coffee, and whole-grain breads, cereals, and bran.8,9

If you have had gastric bypass or small bowel surgery or you are unable to tolerate taking iron orally, then you might need intravenous iron administration.1,4

You will likely note that you feel better after iron supplementation with less fatigue, lightheadedness, dizziness, or shortness of breath, and fewer headaches. 

Take caution: Too much iron can be risky

If prenatal blood tests show your iron level is normal, then you might think that an iron supplement could add an extra health benefit during pregnancy. After all, is there such a thing as doing too much to protect your health and the health of your baby? When it comes to iron, the answer is yes.

Some women with excess iron in their body experience gastrointestinal side effects, like nausea, diarrhea, and constipation.4,8,10,11 More worrisome, studies link excess iron during pregnancy with an increased risk for gestational diabetes and hypertensive disorders of pregnancy.9,12,13 

If you are iron deficient, recent research suggests that taking an additional iron supplement every other day – in addition to the iron in your daily prenatal supplement – might lessen the risk of gastrointestinal side effects.11 

Before taking an iron supplement, it’s important to talk with your health-care professional about the risks and benefits of iron supplementation for your individual situation.

A word from Thorne

Thorne’s Basic Prenatal contains iron bisglycinate, a form that is better absorbed than some others14 and is generally better tolerated.

References

  1. Garner C. Nutrition in pregnancy. UpToDate. https://www.uptodate.com/contents/nutrition-in-pregnancy-dietary-requirements-and-supplements?search=Garner%20C.%20Nutrition%20in%20pregnancy&source=search_result&selectedTitle=2%7E150&usage_type=default&display_rank=2#H717781762. [Accessed June 17, 2024]
  2. Anemia and Pregnancy. American Society of Hematology. http://www.hematology.org/Patients/Anemia/Pregnancy.aspx. [Accessed June 17, 2024]  
  3. Anaemia. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/anaemia#:~:text=Globally%2C%20it%20is%20estimated%20that,age%20are%20affected%20by%20anaemia. [Accessed June 17, 2024]
  4. Auerbach M, Landy HJ. Anemia in pregnancy. UpToDate. https://www.uptodate.com/contents/anemia-in-pregnancy?search=anemia%20in%20pregnancy&source=search_result&selectedTitle=1%7E150&usage_type=default&display_rank=1. [Accessed June 17, 2024]
  5. Anemia in pregnancy. Merck Manual Professional Version. https://www.merckmanuals.com/professional/gynecology-and-obstetrics/pregnancy-complicated-by-disease/anemia-in-pregnancy. [Accessed June 17, 2024]
  6. Iron deficiency anemia during pregnancy: Prevention tips. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/anemia-during-pregnancy/art-20114455. [Accessed June 17, 2024.]
  7. Prenatal vitamins. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/prenatal-vitamins/art-20046945. [Accessed June 17, 2024]
  8. Iron. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/. [Accessed June 17, 2024] 
  9. Iron supplements. Mayo Clinic. https://www.mayoclinic.org/drugs-supplements/iron-supplement-oral-route-parenteral-route/precautions/drg-20070148. [Accessed June 17, 2024]
  10. Iron-Deficiency Anemia. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/anemia/iron-deficiency-anemia. [Accessed June 18, 2024]
  11. Kumar A, Sharma E, Marley A, Samaan MA, et al. Iron deficiency anaemia: pathophysiology, assessment, practical management. BMJ Open Gastroenterol. 2022;9(1):e000759.
  12. Petry, C. Iron supplementation in pregnancy and risk of gestational diabetes: a narrative review. Nutrients. 2022;14(22):4791.
  13. Fang, Z, Zheng S, Xie Y, Lin S, et al. Nutrition and Metabolism. Correlation between serum ferritin in early pregnancy and hypertensive disorders of pregnancy. Front Nutr 2023;10.
  14. Layrisse M, García-Casal M, Solano L, et al. Iron bioavailability in humans from breakfasts enriched with iron bis-glycine chelate, phytates and polyphenols. J Nutr 2000;130(9):2195-2199.