I could hear my patient’s labored breathing even before I entered the room. Her short, sharp breaths were as stressful for me as they were painful for her. I couldn’t figure it out. I was her obstetrician: She saw me every week for her pregnancy and I could not solve, let alone fix this problem. She was in the early third trimester of her pregnancy, she had no complications and no medical condition that could explain this shortness of breath.
I had referred her to cardiology and pulmonology, wondering if the challenge of pregnancy was uncovering a hidden medical problem like pregnancy-induced heart failure. She passed every test and no diagnosis was made. Yet, she was still struggling for breath. I reviewed her labs again. She had mild anemia—but nothing so significant that would explain this persistent shortness of breath. Or could it?
A laissez-faire attitude toward anemia
As an OB-GYN, I often hear patients casually remark, “Oh, I’ve always been anemic,” when reviewing their blood work. In the past, I didn’t consider this dismissal very serious, but now I find the nonchalant attitude concerning. This casual approach to iron deficiency anemia (IDA) reflects what patients are hearing from their physicians: that it’s common, harmless and nothing to worry about.
However, my patients’ experiences have taught me that this view is inaccurate and potentially dangerous. Why? Because iron deficiency—having too little iron in your body—is more than just a minor inconvenience. It’s the most common nutritional deficiency worldwide and can have serious health impacts, especially during pregnancy.
Iron deficiency vs anemia: What’s the difference?
One of the first steps in understanding iron deficiency anemia is to recognize that anemia, simply defined as the pallor of the red blood cell, is a symptom of a disease, it is not the disease itself. The disease is iron deficiency. This is what is under-recognized: Iron deficiency is the root cause of the issue.
Iron deficiency refers to low amounts of stored iron in the body,5 while iron deficiency anemia is merely one way that the body demonstrates that it has low iron stores. One example of this is pregnancy, during which a woman’s iron stores are stressed by the demands of the growing baby. The level of anemia may not be severe—but the iron stores are working hard in so many other functions that those levels start to fall, and symptoms may crop up that don’t correlate well with the minor level of anemia seen on blood tests.
Why iron matters
Iron is used by the human body in hundreds of biological processes. Iron is essential for our development and survival. Just a few of the important processes where iron is essential include: the creation of DNA, oxygen transport and providing the body the ability to create its necessary energy.
Looking at it in that way, iron is one of the most important minerals that the body needs to remain healthy. When you don’t have enough iron, you might experience:
- Fatigue
- Restless legs
- Unusual cravings for non-food items (pica)
- Heart palpitations (arrhythmias)
- Muscle weakness
- Anxiety or depression
- Difficulty concentrating6
For women, iron deficiency can also cause:
In pregnancy, iron deficiency can result in:
- Low birth weight
- Premature birth
- Slower growth of the baby in the womb (intrauterine growth restriction)2
What’s especially concerning is that iron deficiency during pregnancy can lead to negative impacts on fetal brain development, potentially leading to learning difficulties or behavioral issues later in life.3
Therefore, during pregnancy, the major reasons to maintain sufficient iron stores are to protect your own health, improve pregnancy outcomes and foster your baby’s development.
Why women are at higher risk for iron deficiency
Of the nearly 2 billion people on the planet with iron deficiency, the disease predominantly affects women.2 According to the WHO, 37% of pregnant women and 30% of reproductive-aged women worldwide are affected by low iron levels.
Why are women affected so disproportionately? These are the three main drivers of iron deficiency:
- Diet: Women may have lower iron intake, especially if they’re vegetarian or vegan
- Increased need: Pregnancy dramatically increases the body’s iron requirements
- Blood loss: Monthly menstruation leads to regular iron loss
Many women enter pregnancy already low on iron. Then, as the baby grows, the need for iron skyrockets: from 0.8mg daily in the first trimester, to 4mg daily in the second trimester to 6mg daily in the third!
How we test for iron deficiency is important
Despite its high prevalence, iron deficiency remains poorly recognized by clinicians mainly because the screening guidelines from most medical organizations don’t recommend screening for iron deficiency1 specifically, but rather focus on assessing anemia.
But by the time anemia shows up, you’ve already been iron deficient for a while.2 Most medical organizations recommend looking at hemoglobin concentrations to test for iron deficiency anemia. However, the WHO recommends using a test called ferritin to check iron levels. Ferritin is a more accurate way to test for iron deficiency than hemoglobin.5
A personal lesson learned
Remember my pregnant patient with shortness of breath? After testing her ferritin levels, we discovered she was indeed iron deficient. Once we treated her with the iron her body needed, her breathing improved dramatically.
Key takeaways:
- Iron deficiency is common, especially in women, but often overlooked
- It can cause a wide range of symptoms and health issues, particularly during pregnancy
- Standard anemia tests may miss iron deficiency – ask your doctor about ferritin testing
- Don’t dismiss iron deficiency as “normal” or harmless – it’s a health issue worth addressing
By being aware of iron deficiency and its impacts, we can take steps to improve health for women, their children, and everyone affected by this common but serious condition.
References:
1. Abdulrahman, Al-Nadeem, Abdelrahman Sállame, Shamin Choudhury and Jecko Thachil, Clinical Medicine 2021 Vol 21, No 2: 107-113 “Iron Deficiency without anaemia: a diagnosis that matters”
2. Michael K. Georgrieff, MD, American Journal of Obstetrics and Gynecology, October 2020. “Iron deficiency in pregnancy”
3. Sriparna Basu, Dinesh Kumar, Samoa Anupurba, et al. Journal of Perinatologist (2018) 38:233-239. “Effect of maternal iron deficiency anemia on fetal neural development”.
4. Robert T. Means. Nutrients 2020, 12, 447. “Iron Deficiency and Iron Deficiency Anemia: Implications and Impact in Pregnancy, Fetal Development, and Early Childhood Parameters”.
5. World Health Organization Executive Summary: Use of Ferritin Concentrations to Assess Iron Status in Individuals and Populations 2024
6. Barton, James, et al. PLoS One 15 (4), e0232125 2020 Prevalence of iron deficiency in 62,685 women of seven race/ethnicity groups: The HEIRS Study 7. Bothwell, American Journal of Nutrition 2000
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