Abstract: Objective To understand the incidence of overweight and obesity among school age children in Anyang City, Henan Province, the influencing factors of BMI and its relationship with birth weight, and provide a scientific basis for ensuring and promoting children's healthy growth. Methods In this study, a stratified cluster random sampling method was used. In March 2019, students in Anyang City, Henan Province, were selected as subjects, and physical examinations were carried out. At the same time, the parents or guardians of the subjects filled out relevant questionnaires to obtain the information on daily behavioral habits, such as general demographic characteristics, eating habits, family history, and sports and sleep data. The variance analysis or Chi square test was used to compare the general conditions of children with different birth weights. Multivariate logistic regression analysis was used to analyze the influencing factors of BMI in school age children. Results A total of 548 children were enrolled in the study, and at the same time questionnaires survey and physical examinations were carried out. There were 308 boys and 240 girls, with an average age of (8.53±1.77) years, mean BMI (20.58±5.09) kg/m 2, and average birth weight (3 802.53 ±117.77) g. The incidence of low birth weight was 6.0%, and the incidence of macrosomia was 7.7%. The overweight detection rate was 13.7%, and the obesity detection rate was 5.5%. After stratification according to different birth weights, there were differences in breastfeeding, premature birth, father BMI, maternal BMI, and child height in low, normal, and high birth weight (P<0.05). In low and high birth weight infants, the detection rates of overweight obesity were 15.2%, 0.0%, 19.0% and 9.5%, respectively. The incidence of overweight and obesity in high birth weight infants was higher than that in normal birth weight children(P=0.001). Multivariate logistic regression analysis showed that the risk factors for childhood obesity were: high birth weight(OR=1.97, 95%CI=1.23-3.05), premature delivery(OR=1.56,95%CI=1.16-2.13), father BMI exceeding the standard(OR=1.78, 95%CI=1.09-2.58), mother BMI exceeding(OR=2.13,95%CI=1.63-3.40), children's big hip circumference(OR=1.16, 95%CI=1.03-1.87); lower obesity occurred in breastfeeding(OR=0.66, 95%CI=0.23-0.87), height of children being higher(OR=0.84,95%CI=0.51-0.96), and father's height being higher(OR=0.72, 95%CI=0.43-0.90). Conclusion Many factors affect the occurrence of childhood obesity. Parents maintaining proper weight before and during pregnancy and breastfeeding can reduce the incidence of childhood obesity. High birth weight infants tend to develop obesity in childhood, so prevention of obesity should start during prepregnancy and embryonic period.

Key words: Overweight obesity, BMI, Birth weight, Children