What are the most common causes of iron deficiency anemia in infants?

Most Common Causes of Iron Deficiency Anemia in Infants

The most common causes of iron deficiency anemia in infants are feeding non-iron-fortified formula or whole cow's milk (especially before age 1 year), inadequate introduction of iron-rich complementary foods after 6 months, and prolonged exclusive breastfeeding beyond 6 months without iron supplementation or iron-fortified foods. 1

Primary Dietary Risk Factors

Non-Iron-Fortified Formula and Cow's Milk (Option A - Partially Correct)

• Approximately 20%-40% of infants fed only non-iron-fortified formula or whole cow's milk are at risk for iron deficiency by ages 9-12 months. 1
• Early introduction of whole cow's milk before age 1 year is a major risk factor because cow's milk has little iron, may replace iron-rich foods, and can cause occult gastrointestinal bleeding. 1
• Consumption of greater than 24 oz of cow's milk daily after the first year of life significantly increases iron deficiency risk. 1, 2
• Infants fed iron-fortified formula (≥1.0 mg iron/100 kcal) are not likely to have iron deficiency at age 9 months. 1

Breast Milk as Iron Source (Option B - Misleading)

• Breast milk has the highest percentage of bioavailable iron of all milks and formulas, and breast milk provides sufficient iron to meet an infant's needs when combined with appropriate complementary foods. 1
• However, 15%-25% of breast-fed infants are at risk for iron deficiency by ages 9-12 months, primarily when iron-rich complementary foods are not introduced adequately after 6 months. 1
• The issue is not that breast milk is a "poor iron source" in terms of bioavailability, but rather that the total iron content becomes insufficient to meet the infant's needs after iron stores are depleted around 4-6 months. 1

Delayed or Inadequate Introduction of Iron-Rich Solids (Option C - Correct)

• Among exclusively breast-fed infants who were fed cereal starting at age 4 months, only 3% of infants receiving iron-fortified cereal developed iron-deficiency anemia at age 8 months, compared with 15% receiving non-iron-fortified cereal. 1
• Breast-fed infants who do not consume a diet adequate in iron after age 6 months (insufficient iron from supplementary foods) are at high risk for iron deficiency. 1
• Introduction of plain, iron-fortified infant cereal at age 4-6 months, with two or more servings per day, can meet an infant's iron requirement. 1
• Low intake of iron-rich complementary foods is a well-established risk factor, particularly in immigrant families and socioeconomically disadvantaged populations. 2

Maternal Iron Deficiency (Option D - Indirect Factor)

• There is no evidence that iron supplementation of pregnant women improves iron status in their offspring in a European setting. 2
• Full-term infants are born with sufficient iron stores to meet requirements until ages 4-6 months, regardless of maternal iron status during pregnancy. 1
• However, preterm and low-birthweight infants (which may be associated with maternal iron-deficiency anemia during pregnancy) are born with lower iron stores and deplete them by ages 2-3 months. 1, 3

Critical Age-Related Context

• Infants aged 9-18 months face the highest risk of any age group for iron deficiency due to rapid growth coincident with frequently inadequate dietary iron intake. 1, 3, 4
• Iron-deficiency anemia generally does not occur until approximately age 9 months in full-term infants, as iron stores can meet requirements until ages 4-6 months. 1, 3
• After age 24 months, when growth rate slows and diet becomes more diversified, the risk for iron deficiency drops substantially. 1

Answer to Multiple Choice Question

Based on the evidence, the best answers are C (delayed introduction of solids) and A (formula feeding - specifically non-iron-fortified formula or cow's milk). Option B is misleading because breast milk has highly bioavailable iron; the problem is inadequate complementary iron-rich foods after 6 months. Option D (maternal iron deficiency) does not directly cause infant iron deficiency in full-term infants, as they are born with adequate stores. 1, 2