Childhood is an important stage of life, and children in this period have to go through two processes: long knowledge and long body. Although children's growth and development have certain laws, they are influenced by many factors in a certain range, such as genetic factors, nutritional factors, disease factors, social and environmental factors and so on. Among them, genetic factors determine the possibility of children's growth and development, while environmental factors such as nutritional factors and disease factors determine the reality of children's growth and development. The process of children's growth and development is also the interaction between individual genetic factors and environmental factors. Childhood includes three stages: infancy (1~3 years old), preschool (4~6 years old) and school age (7~ 12 years old). This paper mainly aims at preschool children aged 4~6, and expounds the factors affecting their growth and development. Key words Key words: Genetic environment of nutrition and growth and development111,,,genetic factors Genetic factors are the factors we should consider when evaluating children's growth and development. Let's look at the effects of genetic factors on the growth and development of preschool children. Genetic factor is one of the important internal factors that affect children's growth and development, because it determines the possible range of physical development to a certain extent, and the external environmental conditions determine the speed and final level of physical development. The characteristics, potentials, trends and limits of children's growth and development are all influenced by the genetic factors of both parents. The genetic information of race and family has far-reaching influence, such as skin, hair color, facial features, height, sexual maturity and so on. Hereditary diseases, whether chromosome aberration or metabolic defect, have great influence on growth and development. The material basis of heredity is chromosome. It has been proved that there are 23 pairs of chromosomes in each nucleus of human body, of which 22 pairs are the same for men and women, which are called autosomes. The other pair is the chromosome that determines the sex of human body, which is called sex chromosome. Women are represented by XX, and men are represented by XY. There are many genes on the chromosome. At present, it is known that nearly 3 000 human traits are determined by a single gene, which are located at different sites of 23 pairs of chromosomes. People's height, weight, body shape and other traits are controlled by more than two pairs of genes, which are sensitive to the impact of the environment. Identical twins provide the best natural materials for studying the influence of genetic factors on physical growth and development. Studies show that identical twins are not only very similar in appearance, fingerprints, blood type, breathing, heart rate and brain wave patterns, but also have little difference in height and close head circumference, which shows that the physiological function of the body and the development of the skeletal system are greatly influenced by genetic factors. On the contrary, weight is easily influenced by environmental factors. The familial and racial differences in children's growth and development are the concrete embodiment of genetic factors affecting the body. Children who grow up in a good living environment, their adult height depends largely on heredity. Some people think that more than 70% of the adult height of the human body depends on genetic factors, and only 20% depends on environmental conditions such as nutrition and exercise. Usually, the higher the height of parents, the higher the height of children, which is also very common in atavism. However, it is worth noting that the expression of genetic information did not suddenly start at a certain period the day after tomorrow, but began during pregnancy, and it was obvious in infancy. Therefore, it is still a reliable method to predict the final height of 6-year-old children by their appearance height, bone age and life age. Environmental factors Environmental factors Growth and development of environmental factors is not an isolated and spontaneous process, and environmental factors determine the reality of growth and development. The environmental factors that affect the growth and development of preschool children mainly include the following aspects. (1) Nutritional factors Nutrition is the material basis for ensuring children's growth and development. Nutritional deficiency or unreasonable diet will not only affect development, but also lead to various nutritional deficiencies. 4~6 years old is the preschool stage, its growth rate is slightly lower than that before 3 years old, but it is still in the rapid growth stage, and the demand for heat energy and nutrients is still relatively higher than that of adults. 1, nutritional requirements Preschool children are in the growth and development period, with increased activity ability and activity, increased calorie consumption, and their needs are still relatively higher than those of adults. The heat energy supply of boys and girls at the age of 4 is 6. 1mj (1450kcal) and 5.9mj (1400kcal) respectively, and it increases to 7. 1mj (1700kcal) and 6.7mj at the age of 6. Similar to children, we should also pay attention to the individual differences in heat demand. It is necessary to prevent insufficient intake of heat energy and obesity caused by excessive intake. The rapid muscle development of preschool children, coupled with the growth of internal organs and the maturity of synthetic functions such as enzymes and hormones, requires a lot of protein. 45~55g protein should be added every day. Among all kinds of nutrients that affect children's growth and development, the role of minerals and trace elements has been paid more and more attention. Adequate supply of calcium and vitamin D can not only affect the growth of bone canal and the increase of bone hardness in preschool children, but also be related to the health of permanent teeth. Because at this stage, although children's deciduous teeth have come out, permanent teeth will start to grow around 6 years old, but their calcification process begins long before teething, so the nutritional status of calcium and vitamin D is very important. The calcium supply of children in China is 800mg, which is consistent with the requirements of adults. Zinc participates in the synthesis of more than 50 enzymes in human body, which plays an important role in the synthesis of protein. Children need zinc before and after birth and during their vigorous growth and development. Iodine is an important raw material for the synthesis of thyroxine, and fluorine is a component of bones and teeth, which has a direct impact on children's growth and development. 2. Meal arrangement Understand the nutritional needs of preschool children, and then the most important meal arrangement, especially preschool, is the stage when lifelong eating habits begin to form, and good eating habits need to be cultivated. The gastrointestinal digestive function of preschool children is not fully developed, and the demand for nutrients is relatively higher than that of adults, so if you eat exactly the same food as adults, you can make the intake of thermal nutrients insufficient. In addition, at this stage, children are easily excited, inattentive, and have no intention to eat, which may lead to insufficient food intake; But sometimes due to the large and small amount of activity, the food intake often fluctuates, so don't worry. At this stage, children's imitation ability is enhanced and they are easily influenced by their parents' eating habits. Partial eclipse and food choice are often formed at this stage. According to the survey, the dietary structure of preschool children in Beijing city generally requires too much quality and refinement, and there are unreasonable situations such as more fat, less sugar, more animal protein, less plant protein, more fruits and less vegetables. Therefore, it is impossible to obtain a balanced diet, and the intake of calcium, vitamins A and B is generally low. On the one hand, we should ensure that children have enough time for outdoor activities, stimulate appetite and absorb necessary nutrition, and at the same time, we should pay attention to adjustment and improvement in diet composition and cooking methods. Preschool is the stage when lifelong eating habits begin to form, so we should diversify our food, encourage and guide us to eat different foods, and cultivate good eating habits that are not picky eaters and partial eclipse. Pay attention to the timing of eating, and add a snack to the three meals. In addition, to cultivate children's clean and hygienic habits, parasitic diseases are also one of the causes of malnutrition. (2) Disease factors Any acute or chronic disease can have a direct impact on children's growth and development, and the degree of impact depends on the part involved, the length of the disease course and the severity of the disease. Generally, the impact of acute diseases on growth is temporary, especially in the case of good nutritional status, which can be quickly recovered. However, repeated respiratory infections and diarrhea, if not treated properly, will often affect the growth and development of children. Chronic infection, chronic hepatitis, chronic nephritis, asthma, heart disease, anemia and other long-term diseases will affect height growth. In addition, chromosomal abnormalities, endocrine diseases, skeletal and cartilage developmental disorders and other major diseases will lead to significantly lower height than children of the same age, which is called pathological dwarfism in medicine. Therefore, active prevention and treatment of diseases is of great significance to growing children. Through early diagnosis and treatment, the growth damage caused by some diseases can be completely or partially recovered. (3) A reasonable living system can promote the growth and development of preschool children. Reasonable arrangement of a regular and rhythmic life system ensures that children have enough outdoor activities and appropriate study time. Regular meals and adequate sleep can promote children's growth and development. Because under a reasonable living system, the activities and rest of all parts of the body, including the brain, can be alternated appropriately, and timely nutrition supplementation can ensure normal energy metabolism and promote the full play of all parts of the body. After many preschool children enter kindergarten, their height, weight and motor development progress are often more significant than at home because of their regular life, regular work and rest and moderate diet. Outdoor activities can promote metabolism in the body, increase the oxygen supply to the brain, and at the same time relieve the continuous tension of the brain, so that the function of tired brain cells can be restored. Physical exercise can speed up the whole body blood circulation and improve the nutrition of muscle and bone system. Proper exercise can increase the stimulation to the epiphyseal plate of bones, accelerate the proliferation of bone cells, and thus promote the growth of bones. In addition, physical exercise can also stimulate the pituitary gland to secrete growth hormone, accelerate children's growth and development, and promote children's growth and height. From the research results of the change of growth hormone concentration in blood within 1 day, it can be known that the growth hormone concentration increases obviously at night, and the endocrine system releases much more growth hormone than during the day. Therefore, arranging children's adequate sleep is a necessary condition to ensure their normal physical development. Of course, the role of nutrition cannot be ruled out, but the influence of life system is also very important. (4) Seasonal and climatic factors. Seasonal and climatic factors also have certain influence on children's growth. The influence of seasons on growth and development is obviously reflected in height and weight. Generally, the height growth is the fastest in spring, the weight growth is the fastest in autumn, and some children lose weight in hot season. The annual weight gain is the most from September to February, with an increase of about 2/3 of the whole year. March-May is the fastest season for the growth of tree height, and the growth of tree height is about 2-2.5 times that of 9-65438+February. (V) Environmental Pollution Since June this year, cyanobacteria have exploded on a large scale in several major lakes in China. Please think about how to deal with its impact on people's health. Environmental pollution hinders children's growth and development. For children's health, the main environmental pollution includes water pollution, air pollution, soil pollution and food pollution. Diarrhea is the highest mortality among water-borne diseases. It is estimated that more than 1.3 million children worldwide die of diarrhea every year, of which 1.2% are children under 5 years old in developing countries. Other diseases with the same route of transmission as diarrhea include hepatitis A, hepatitis E, dysentery, cholera and typhoid fever. In addition, water can also spread some other diseases, such as skin infection, trachoma and schistosomiasis. Air pollution is also an important factor affecting children's growth and development. Many sick children get sick because they breathe inhalable particles and sulfur dioxide in the air. Children's respiratory system is in the developmental stage, and they are more sensitive to indoor and outdoor air pollution than adults. Researchers in the former Soviet Union conducted a follow-up study on urban children with air pollution for more than 10 years, and found that environmental pollution has obvious influence on the development of children's physiological functions (such as vital capacity and muscle tension). Indoor air pollution may induce blood diseases in children, which is a common concern at present. According to the statistics of hematology department of Beijing Children's Hospital, 90% children with leukemia in this hospital have been renovated within half a year. Experts believe that children have different hematological characteristics from adults, such as unstable hematopoietic function, poor hematopoietic reserve capacity, susceptible to infection of hematopoietic organs, and prone to nutritional deficiency of hematopoietic organs. Therefore, experts speculate that the impact of excessive formaldehyde on children's hematopoietic organs may be more serious than that of adults. The harm of soil pollution to children's health is mainly concentrated in the body through the food chain, which is finally reflected in the occurrence of diseases. Regarding food pollution, the survey shows that the aluminum content of cans is 3~6 times higher than that of bottled drinks. If you drink cans often, it will inevitably lead to excessive aluminum intake. In addition, excessive pigment and essence will cause loss of appetite and indigestion, and will also hinder children's development.