Anemia is defined as a lower than normal number of red blood cells or amount of hemoglobin (blood pigment) in the peripheral blood. It is both a description of a symptom and often used as the name of an independent disease. According to the survey results in recent years, the anemia rate of children under 5 years old in China is more than 30%, of which more than 90% are nutritional iron deficiency anemia, mostly in infants and children from 6 months to 2 years old. The relationship between the iron content of the organism at birth and anemia There is no definite relationship between iron deficiency anemia of the mother during pregnancy and anemia of the infant, because the placenta can transport iron from the mother with low serum iron content to the fetus with high serum concentration, regardless of the iron deficiency of the mother or the quality of the diet, about 10% of iron enters the fetus after inputting iron labeled with isotopes. Therefore, at birth, the hemoglobin, serum ferritin and serum iron concentrations of the newborn do not differ significantly, regardless of the mother’s anemia, and are not proportional to the mother’s hemoglobin. Even if the mother suffers from moderate or severe anemia, the infant’s serum ferritin can still be within the normal range. 2. The relationship between growth rate and anemia Blood volume increases rapidly. A normal infant’s weight increases 1-fold by the time it reaches 5 months of age. Premature infants increase even faster, up to 6 times by the age of 1 year. If the hemoglobin is 19g/dl at birth, it drops to about 11g/dl at 4.5-5 months of age, which can be maintained by using only the stored iron, so there is no need to add iron to the food. Unlike preterm infants, however, their needs far exceed those of normal infants. If a normal infant gains one times its body weight and keeps its hemoglobin at 11g/dl, the iron stored in its body is sufficient. Therefore, if there is any obvious iron deficiency anemia before the weight growth is 1 times, it is usually not due to iron deficiency in the diet, and other causes must be found. 3. Infants are mainly fed with dairy foods. The iron content of these foods is extremely low. The iron content of breast milk is related to the mother’s diet, generally containing 1.5mg/L. Cow’s milk has 0.5-1.0mg/L, and goat’s milk has even less. The absorption rate of iron in milk is about 2-10%, and the absorption rate of iron in human milk is higher than that of cow’s milk (the absorption rate of iron in human milk can increase to 50% when there is iron deficiency). Infants within the first 6 months of life can maintain hemoglobin and stored iron within the normal range if they are breastfed in adequate amounts. Therefore, when breastfeeding is not possible, iron-fortified formula should be fed and complementary foods should be added in a timely manner; otherwise, anemia can occur when the stored iron is depleted after the weight growth is doubled. Anemia can also occur in breastfed children after 6 months of age if no complementary food is added. According to the investigation of the causes of 39 cases of microcytic anemia in Beijing Children’s Hospital, 65% were artificially fed and some breastfed children did not add complementary foods in time. In older children, anemia is caused by poor eating habits, refusal to eat, partial eating or poor nutritional supply each time. 4.Long-term small amount of blood loss 30% of the total amount of iron in the body, if the acute blood loss does not exceed 1/3 of the total amount of blood, it can be recovered quickly without additional iron supplements, and anemia will not occur. In the case of long-term chronic blood loss, every 4ml of blood loss is equal to 1.6mg of iron loss, and although the daily blood loss is not much, the iron consumption is more than 1 times the normal amount, which can cause anemia. Common chronic blood loss can also be due to gastrointestinal malformations, diaphragmatic hernia, polyps, ulcer disease, esophageal varices, hookworm disease, epistaxis, thrombocytopenic purpura, pulmonary ferritinosis, and excessive menstruation in young girls. 5, other causes of long-term diarrhea and vomiting, enteritis is seriously affect the appetite of children, reduce the digestive and absorption function of the gastrointestinal tract, resulting in a variety of micronutrient deficiencies, resulting in serious impact on the growth and development of babies; can also affect the development of pediatric brain cells and cause intellectual backwardness, hyperactivity, inattention; reduce the body’s immunity so that babies are prone to repeated infections.