Which group of patients is most likely to develop iron deficiency from increased need?

December 29, 2025 •

4 min read

According to the World Health Organization, iron deficiency is the most common nutrient deficiency worldwide. Pregnant women represent the group of patients most likely to develop iron deficiency from increased need, due to the significant physiological demands of expanding blood volume and fetal development. Other high-risk groups include infants, young children, and adolescents experiencing rapid growth, as well as high-performance athletes with elevated iron requirements.

Quick Summary

This article explores various patient populations that face a higher risk of developing iron deficiency due to physiological demands. It details why pregnant women, rapidly growing infants and children, and elite athletes are particularly susceptible. The content examines specific risk factors and physiological mechanisms behind their increased iron needs.

Key Points

Pregnant Women: Due to a major increase in blood volume and providing iron for the developing fetus, pregnant women have the highest iron requirements and are the most susceptible patient group.
Infants and Young Children: Rapid growth in the first few years of life, coupled with depleting iron stores present at birth, makes infants and toddlers highly vulnerable, especially those born prematurely.
Adolescents: The growth spurts of puberty and the onset of menstruation for girls drive a significant increase in iron demand during teenage years.
Endurance Athletes: Intense training and unique mechanisms of iron loss, such as hemolysis and gut bleeding, put endurance athletes at a higher risk of deficiency.
Iron Loss vs. Increased Need: It is important to distinguish between iron deficiency from blood loss (e.g., heavy periods, GI bleeding) and deficiency from physiological demands (e.g., pregnancy, growth) when assessing a patient's risk.
Early Detection: Regular monitoring of iron status is crucial for at-risk populations, as iron deficiency can occur before anemia develops and can cause cognitive or developmental issues.

The body requires sufficient iron for crucial functions like oxygen transport via hemoglobin, energy metabolism, and cellular growth. When iron demand outpaces intake or stores, iron deficiency can result. For some patient groups, this imbalance is not due to dietary inadequacy alone, but to a dramatically increased need driven by specific physiological states.

Pregnant Women

Pregnancy dramatically increases a woman's iron needs. A pregnant woman's blood volume expands by 20% to 30%, necessitating more iron to produce the extra hemoglobin for this increased volume. Additionally, a substantial amount of iron is needed for the fetus's growth and development, particularly for brain development, and to build the fetus's own iron stores, which will sustain the infant during the first 6 months of life. The placenta, a highly metabolic organ, also requires a significant iron supply. These combined demands make pregnant women one of the most vulnerable groups. The iron requirement for pregnant women is 27 mg per day, compared to 18 mg for non-pregnant women of reproductive age.

Increased Risk Factors During Pregnancy

Multiple pregnancies: Women carrying multiples need an even greater amount of iron to support the growth of more than one fetus.
Closely spaced pregnancies: Having pregnancies close together can deplete iron stores before they have had a chance to fully recover.
Poor pre-pregnancy iron status: Women who enter pregnancy with low iron reserves are at an immediate disadvantage.
Morning sickness: Frequent vomiting can lead to poor dietary intake and further reduce iron levels.

Infants and Young Children

Infancy and early childhood are periods of rapid growth and development, which translates to a high demand for iron. A full-term infant's iron stores, built up in the womb, are usually sufficient for the first 4–6 months. After this period, their needs increase significantly as these stores are depleted. Iron is vital for brain maturation, cognitive development, and supporting the expansion of muscle mass and blood volume.

Factors Increasing Iron Need in Infants

Premature or low birth-weight babies: These infants miss the critical final trimester of iron accumulation and are born with insufficient iron stores, placing them at very high risk.
Introduction of solid foods: Infants who are not given iron-fortified cereals or other iron-rich complementary foods after 6 months are at risk, especially if their primary intake is cow's milk, which is low in iron and can inhibit absorption.
Lead exposure: Lead interferes with the body's ability to produce hemoglobin, exacerbating iron deficiency.

Adolescents

The rapid growth spurts of puberty place a significant strain on the body's iron stores, particularly in girls with the onset of menstruation. Adolescent boys experience increased iron needs to support muscle mass and blood volume expansion. However, menstruating adolescent girls are at a higher risk due to both growth and iron loss through blood. The iron requirement for adolescent girls (14-18 years) is 15 mg per day, notably higher than that for boys of the same age (11 mg).

Iron Deficiency in Adolescents

Heavy menstrual periods: For teenage girls with heavy periods, blood loss can quickly deplete iron reserves.
Dietary choices: Restrictive dieting, common in this age group, and vegetarian or vegan diets, can lead to inadequate iron intake.
Teenage pregnancy: The combined needs of a growing adolescent and a developing fetus create an extremely high demand for iron.

Athletes

Endurance athletes and those who train intensely are another group with heightened iron requirements. Their increased iron need is driven by several factors.

How Athletics Increase Iron Demand

Increased red blood cell production: High-intensity training boosts the production of red blood cells to carry more oxygen, requiring more iron.
Iron loss through sweat: Athletes lose a small amount of iron through heavy sweating.
Gastrointestinal bleeding: Some endurance runners may experience minor, but chronic, blood loss from the gastrointestinal tract due to the physical stress of intense training.
Foot-strike hemolysis: Repetitive impacts from running on hard surfaces can cause red blood cells to break down in the feet, leading to a form of iron loss.
Hepcidin response: Intense exercise can temporarily increase levels of the hormone hepcidin, which limits iron absorption in the gut.

Comparison of At-Risk Groups for Iron Deficiency


Patient Group	Primary Mechanism for Increased Need	Common Symptoms	Treatment Approach
Pregnant Women	Blood volume expansion and fetal development.	Fatigue, dizziness, shortness of breath, restless legs syndrome.	Prenatal vitamins, targeted iron supplements, diet rich in iron.
Infants & Young Children	Rapid growth and depletion of fetal iron stores.	Pale skin, developmental delays, behavioral issues, pica.	Iron-fortified formula/cereals, limiting cow's milk, supplements if needed.
Adolescents	Growth spurts (both sexes) and menstruation (girls).	Fatigue, poor concentration, reduced school performance, headaches.	Dietary adjustments, addressing heavy periods, iron supplements.
Endurance Athletes	Increased red cell turnover, sweat loss, and gastrointestinal bleeding.	Decreased endurance, fatigue, higher heart rate, impaired performance.	Dietary iron, strategic supplementation, sometimes IV iron.
Chronic Blood Donors	Frequent donation of whole blood.	Fatigue, paleness, and other typical anemia symptoms.	Iron supplements recommended post-donation for frequent donors.

Conclusion

While iron deficiency can affect anyone, specific groups face a significantly elevated risk due to physiological demands that increase their need for this vital mineral. Pregnant women, experiencing a massive increase in blood volume and supporting fetal growth, are arguably the most vulnerable. However, rapidly growing infants and adolescents, as well as endurance athletes, also face substantial increases in iron demand. Understanding these unique needs is critical for prevention, early diagnosis, and appropriate treatment. For these at-risk populations, proactive screening and management of iron status, often through dietary adjustments or supplementation, are essential for maintaining health and function. In severe cases, or when oral treatment is insufficient, intravenous iron therapy may be required. A personalized approach to monitoring and treatment is therefore paramount for ensuring optimal outcomes.

Authoritative Link

For comprehensive information on iron and dietary recommendations by life stage, consult the NIH Office of Dietary Supplements fact sheet.

Frequently Asked Questions

Pregnant women need significantly more iron for two main reasons: to support the large increase in their own blood volume (expanded by 20-30%) and to provide enough iron for fetal development and growth. This elevated demand helps create the additional red blood cells needed to supply oxygen to both the mother and the developing baby.

The primary reason is the rapid growth characteristic of infancy and toddlerhood, which creates a high demand for iron. Additionally, their iron stores obtained during gestation are largely depleted by 6 months, so they become dependent on external dietary iron for their continued development.

The onset of menstruation in adolescent girls is a major factor increasing their iron requirement. The monthly blood loss from menstruation can deplete iron stores, and when combined with the high demands of a growth spurt, it places them at a particularly high risk for iron deficiency.

Athletes are susceptible due to several factors including increased production of red blood cells to meet oxygen demands, minor blood loss through the gastrointestinal tract due to exercise stress, and foot-strike hemolysis (red blood cells breaking down from impact). They also lose some iron through sweat and can experience reduced iron absorption after intense workouts.

In many high-risk patients, especially pregnant women and those with already depleted stores, diet alone is not enough to meet the dramatically increased need. Supplemental iron, in addition to an iron-rich diet and vitamin C to aid absorption, is often necessary to prevent or treat deficiency effectively.

Initial symptoms can be subtle and non-specific, including extreme fatigue, generalized weakness, paleness, and shortness of breath with activity. As the deficiency worsens, more specific signs like restless legs syndrome, brittle nails, and cognitive issues can appear.

Yes, it is possible and even common. Iron deficiency progresses in stages, starting with the depletion of body iron stores (reflected by low ferritin levels) before hemoglobin production is affected and anemia develops. This pre-anemic stage can still cause symptoms like fatigue and impaired cognitive function.