Anemia Caused by Inadequate RBC Production
Infants are born with high levels of hemoglobin and RBCs in their blood. This occurs in the fetus to help fetal blood carry enough oxygen while the developing baby is in the relatively oxygen-poor environment inside the uterus. After birth, when more oxygen is available, the baby's hemoglobin level normally drops to a low point at about 2 months of age, a condition known as physiologic anemia of infancy. After this occurs, the infant's body gets the signal to increase RBC production. This temporary and expected drop in the blood count is considered normal and no treatment is needed.
Anemia also occurs when the body isn't able to produce enough healthy red blood cells. This can happen because of a deficiency of iron or certain other substances in the body or from inherited defects or diseases that interfere with the production of red blood cells.
Iron is essential for the production of hemoglobin in red blood cells. Poor dietary iron intake (or excessive loss of iron from the body) leads to iron-deficiency anemia, the most common cause of anemia in children. Iron-deficiency anemia can affect children at any age, but it is most commonly seen in children under 2 years of age, and in teens, particularly in adolescent girls who have started menstruating.
During the first 6 months of life, babies are usually protected against developing iron deficiency due to the stores of iron built up in their bodies while they are in the uterus. However, by the second half of the first year of life, as infants continue to undergo significant growth, often they do not take in enough iron through breast milk alone or regular cow's milk (which contains less iron than fortified infant formula) to meet their iron needs. Regular cow's milk can also cause some infants to lose iron from their intestines, and drinking lots of it can make an infant less interested in eating other foods that are better sources of iron. For these reasons, regular cow's milk is not recommended for children until they reach 1 year of age and are eating an iron-rich diet.