What is the most common cause of anemia in infants?

• A. Iron deficiency
• B. Physiologic anemia of infancy
• C. Hemolytic disease of the newborn
• D. Vitamin B12 deficiency

Answer: (B)

The most common cause of anemia in infants is physiologic anemia of infancy. This condition typically occurs within the first few months of life as a result of the natural decline in fetal hemoglobin levels after birth. During this period, infants may exhibit lower hemoglobin concentrations since they are transitioning from the high fetal hemoglobin levels present during gestation to adult hemoglobin levels.

Physiologic anemia of infancy is a normal part of development as the body adjusts to the extrauterine environment and begins to produce red blood cells at a more adult-like rate. This anemia is generally self-limiting and resolves as the infant matures, particularly around the 2-3 month mark when erythropoiesis (the production of red blood cells) begins to stabilize and increase.

In contrast, while iron deficiency is a well-known cause of anemia in older children and adults, it is less common in the immediate neonatal period because infants are typically born with adequate iron stores to last them for the first several months. Hemolytic disease of the newborn and vitamin B12 deficiency also contribute to anemia, but they are not as prevalent as physiologic anemia, especially in the early stages of life. Thus, physiologic anemia of infancy is considered the most common cause