Objective: To analyze the association between masculine and feminine traits, gender role in students and family factors, and to provide a scientific basis for promoting the healthy development of children and adolescents gender role. Methods: Cluster random sampling method was used to selected 823 students from 2 schools of Xiamen in May, 2018, participants were asked to report individual masculine and feminine traits through the Child s Sex Role Inventory, and then gender role was divided into four types (masculine, feminine, androgynous, undifferentiated). Non parametric tests, generalized linear model, and Logistic regression model were used to explore the association between masculine and feminine traits, gender role and family factors. Results: Compared with the boys from the nuclear family, the masculine traits were lower in boys of other families by 0.282( 95% CI = -0.452 --0.110), and the feminine traits were also lower by 0.192 (95% CI =-0.369--0.014). Compared with boys of middle socioeconomic status (SES), the masculine traits of boys from low SES decreased by 0.157 (95% CI =-0.286--0.029), and the feminine traits decreased by 0.140 (95% CI =-0.274--0.005). The proportion of androgynous in boys from other families was significantly lower than boys from the nuclear family ( OR =0.45, 95% CI =0.21-0.94), with the proportion of undifferentiated significantly higher than nuclear family 2.33 (95% CI =1.22-4.44). The proportion of androgynous in boys from low SES was significantly lower than boys from middle SES ( OR =0.59, 95% CI =0.35-0.99), with the proportion of undifferentiated significantly higher than middle SES 1.62 (95% CI =1.00-2.65). Among girls, the differences in masculine and feminine traits and gender role of different family factors were not statistically significant ( P >0.05). Conclusion The masculine and feminine traits and gender role in students are associated with family structures and socioeconomic status, especially in boys. Therefore, the family environment is an important factor affecting children s gender role, and the healthy development of children s gender role needs parents attention and correct guidance.

Objective: To analyze the correlation between the scores of masculinity and femininity and parental rearing pattern in lower grade primary school students in Xiamen, and to provide a policy suggestions and reference basis for establishing a correct concept of gender role among children and adolescents. Methods: A cluster random sampling method was used to select 823 students from two primary schools in Xiamen. Masculinity and femininity scores were assessed by Children s Sex Role Inventory(CSRI), while attitudes and behaviors of parental rearing pattern were obtained through EMBU. Regression analyses were used to analyze the correlation between masculinity and femininity scores and parental rearing pattern. Results: Masculinity scored 2.82 ( 2.41 ,3.24) and 2.82 (2.47,3.18), femininity scored 2.87 (2.40,3.20) and 3.13 (2.73,3.47) among boys and girls, with no significant gender difference ( P >0.05). Masculinity and femininity scores varied significantly by parental emotional warmth and understanding(father: Z/H =44.61, 37.24；mother: Z/H=41.68, 46.64, P <0.05). Among boys, increasing parental emotional warmth and understanding and paternal excessive interference were associated with higher masculinity and femininity scores. Increasing rejection and maternal deny were associated with lower masculinity scores. Among girls, increasing the understanding of emotional warmth of fathers was associated with masculinity and femininity scores, increasing excessive interference from mothers was associated with lower masculinity scores ( P <0.05). Conclusion There are gender differences in the relationship between parental rearing pattern and masculinity and femininity scores. In particular, increasing parents emotional warmth and understanding and reducing mothers punishment and harshness, rejection and denial, and other negative parenting styles could facilitate healthy development of masculinity and femininity among primary school students.

Objective: To investigate the association between the combined effect of height growth and overweight/obesity with elevated blood pressure in Chinese children. Methods: Based on a cohort study of puberty development in Xiamen, a cluster sampling method was used to select 1 313 children whose complete height, weight and blood pressure levels at baseline were obtained in 2017 and during a follow up in 2019. The incidence of elevated blood pressure was compared between four different subgroups, and multivariate Logistic regression was performed to analyze the combined effect in boys and girls. Results: Among 1 313 children, the prevalence of elevated blood pressure at baseline was 25.2%. After 2 years of follow up, the incidence of elevated blood pressure was 19.7% and 23.4% in boys, and 16.6% in girls. After adjusting for factors including age, sex, family history of hypertension, sleep time, intake of fruits, vegetables, sugar sweetened beverages, and meat products, multivariate Logistic regression analyses showed that children in the high height growth and overweight/obesity group were more likely to exhibit a higher incidence of elevated blood pressure (overall:RR=2.41，95%CI=1.44-4.04；boys：RR=2.69，95%CI=1.45-5.02). Among girls, the risk of elevated blood pressure in the low height growth and overweight/obesity group also increased significantly (RR=4.47, 95%CI=1.45-13.75). Conclusion A large magnitude of height growth and being overweight/obesity were associated with elevated blood pressure in children, especially boys. Therefore, interventions that are targeted toward obesity prevention in children before pubertal growth spurts in height may be beneficial to reduce childhood high blood pressure.

Objective: To explore the relationship between one-child and low height level classification among children and adolescents, and the effects of fruits, vegetables and physical activities on this association, and to provide as cientific reference for probing into and improving the differences of their height level between one child and child with siblings. Methods: Using stratified cluster sampling method, 93 primary and secondary schools in 7 provinces and cities in China were selected for physical examination and questionnaire surveys. A total of 40 978 primary and middle school students aged 7-17 were selected. A multilevel Logistic regression model was used to analyze. Results: Univariate analysis found that being one-child was less likely to be classified as low height level(OR=0.63, 95%CI=0.58-0.67); the multilevel model also found that the probability that one-child being at low height level was still lower(OR=0.78, 95%CI=0.73-0.85), and daily vigorous-intensity physical activities ≥1 h (OR=0.92, 95%CI=0.85-0.99) and daily vegetables and fruits intake ≥5 servings (OR=0.83, 95%CI=0.75-0.92) could also reduce the probability of being at low height level. Hierarchical analysis found that when vegetables and fruits intake and physical activities time were sufficient, there was no longer a significant difference in the height level classification between one-child and child with siblings(P>0.05). Conclusion Being one-child could be a protective factor for the height level classification of children and adolescents. Adequate intake of vegetables and fruits and time of vigorous-intensity physical activities could fill the gap of height level classification between of being one-child and child with siblings. Effective behavioral intervention measures should be taken to protect the healthy growth of height among children and adolescences.

Objective: To investigate the prevalence of drinking-tea type endemic fluorosis among children in Lhasa, Tibet, and to provide basic data for the early prevention of dental fluorosis and skeletal fluorosis among children. Methods: Stratified cluster random sampling method was used to select primary school 1 991 students in 6 counties. Results: The detection rate of dental fluorosis was 27.2%, the index of dental fluorosis was 0.44, and the total severity of fluorosis prevalence was identified as very mild among 6 counties. The detection rate of dental fluorosis increased with the age of the children：male and female increased by 36.2 and 28.5 percentage points,respectively. There was no significant difference between male and female students(χ2=0.08, P> 0.05). The urine fluoride test results suggested that urine fluoride concentration among participate children was below the standard limits value(geometric mean of urinary fluorine <1.4 mg/L). Conclusion The prevalence of tea-drinking type endemic fluorosis among children in Lhasa is more serious compared with that from other regions of China. The cumulative effect of fluorine in human body makes older students more prone to dental fluorosis. It is suggested that more school-based health education programs should be carried out to prevent tea drinking type endemic fluorosis.

Objective: To explore the relationship between nutritional status and puberty onset in boys, and to provide a reference for promoting the development of physical and mental health of boys. Methods: A total of 2 724 boys aged 7 to 12 years from grade 2 to 6 were recruited from Xiamen city by cluster sampling method in 2017. The nutritional status was assessed by physical examination, pubertal developmental status was evaluated by rating scales of Tanner and Prader orchidometer, and puberty timing was determined by the P25 age of puberty onset. The association between nutritional status and puberty onset was estimated by logistic regression model. Results: Pubertal onset was found in 29.0% of the boys and the incidence of early pubertal timing was 2.9%. The prevalence of puberty onset in wasting, normal weight, overweight and obesity boys was 19.6%, 28.7%, 34.4% and 31.5%, respectively. The age of puberty onset was significantly earlier in obese boys (F=3.23, P<0.05). The results of Logistic regression analysis showed that with the increase of BMI, the possibility of puberty onset and risk of early pubertal timing increased. After adjusting for confounding factors, the odds of puberty onset in boys with wasting decreased by 64.0% (OR=0.36, 95%CI=0.22-0.60), the possibility of puberty onset and risk of early pubertal timing in boys with obesity increased by 78.3% (OR=1.78, 95%CI=1.14-2.79) and 192.9% (OR=2.93, 95%CI=1.46-5.86), respectively. These relationships were more pronounced in boys of households with lower economic level (P<0.05). Conclusion BMI was positively correlated with puberty onset in boys, the odds of puberty onset and risk of early pubertal timing were significantly increased in obese boys, especially in those with low household economic level.

Objective: To explore the association between breastfeeding and the type of obesity in children and adolescents, and to provide a theoretical basis for the identification and intervention of influential factors of different types of childhood obesity. Methods: Using stratified cluster sampling method, 93 primary and secondary schools in 7 provinces and cities in China were selected for physical examination and questionnaire surveys. Totally, 30 437 primary and middle school students aged 7-17, with completed information, were selected. A multivariable Logistic regression model was used to analyze the association between breastfeeding and different types of obesity. Results: The breastfeeding rate of students was 69.8%. The rates of general obesity, simple abdominal obesity, and combined obesity in the breastfeeding group were 7.1%, 3.9%, and 18.7%, the non-breastfeeding group were 7.0%, 4.7%, and 19.5%. The differences were statistically significant(χ2=14.04,P<0.01). Univariate analysis found that breastfeeding significantly reduced the risk of simple abdominal obesity in children and adolescents(OR=0.81,95%CI=0.72-0.92,P<0.01) with normal(BMI non-overweight and obesity and waist Conclusion Breastfeeding is a protective factor for children with simple abdominal obesity and combined obesity, and the rate of breastfeeding in China should be further improved.

Objective: To explore the epidemiological characteristics of injury among middle school students in Zhongshan city, Guangdong Province, and to provide evidence for appropriate student injury prevention strategies and injury monitoring programs. Methods: The cluster random sampling method was used to collect injury information among 2 212 middle school students in urban and suburban areas of Zhongshan city. SPSS 22.0 was used for statistical analysis. Results: Among all the 2 212 middle school students, the incidence of injury was 17.95%. The incidence of injuries (20.9%)and mutiple injuries(6.67%)among boys was higher than that of girls(15.42%,4.61%),and the differences were of statistical significance(χ2=11.21,4.45,P<0.05). The incidence of multiple injuries among junior high school students(6.70%) was higher than that among high school students(4.48%)(χ2=5.20，P<0.05). The injury occurred in the school (63.76%) was higher than that occurred outside of the school (36.24%). Most injures were more likely to occur in sports area in school(33.16%),and most injuries were found occured while doing physical activities(38.01%). Conclusion The prevention of injury among middle school students should focus on junior high school students and male students. School-based injury prevention and health education should focus on campus sports-related injury.

Objective: To explore the relationship between paternal smoking and risk of childhood obesity , and to provide theoretical support for the identification and intervention of risk factors of obesity among children and adolescents. Methods: Physical examination and questionnaire survey was conducted among 38 228 students from 7 provinces in China. Log-binomial regression model was used to estimate the relationship between passive smoking and childhood obesity. Results: The students were divided into non-smoking goroup and smoking group auording to whether their fathers smoked or not, the former included 19 096 students(50.0%), and the latter included 19 132 students(50.0%). The obesity rate of the no-smoking group was 10.2%, the obesity rate from smoking group was 12.7%, the differences were of statistical significace (χ2=58.42, P<0.01). Univariate analysis showed that the risk for obesity in smoking group was 1.24 times higher than those in non-smoking group (95%CI=1.18-1.32, P<0.05). Adjusting regression indicated that the risk for obesity in smoking group was 1.28. times higher than non-smoking group (95%CI=1.21-1.35, P<0.01). Conclusion Paternal smoking increases the risk of obesity in children and adolescents. Parents should avoid smoking and other unhealthy lifestyle, so as to effectively control the incidence of obesity in children and adolescents.

Objective: To understand the status of vision of Tibetan students aged 7-18 in China, and to provide the theoretical basis for prevention and controlling work of short-sightedness and making relevant policies. Methods: Cross-sectional survey method was applied to collect information of the eyesight of 2 418 Tibetan students and that of gender, age and work-and-rest habit of 1 910 students, and the status of eyesight of Tibetan students was analyzed, and Logistic regression analysis method was used to probe into the influencing factors of eyesight. Results: The mean left eye visual value was (4.75±0.33),and the median was 4.75(P25=4.5，P75=5.0). The mean right eye visual value was (4.74±0.33),and the median was 4.90(P25=4.5, P75=5.0). 1 520 students were detected with myopia, with the detection rate of 62.9%. The prevalence of myopia among Tibetan female students was higher than that of male (P<0.01). The detection rate of myopia was increased with age both in left and right eyes. Logistic regression model showed that students with insufficient physical education courses each week were associated with evaluated risk of myopia,compared with those with sufficient courses(OR=1.43, 95%CI=1.05-1.94, P<0.05). Conclusion The prevalence of myopia among Tibetan students aged 7-18 years old is rather high, and females are worse than males, senior students were worse than junior students. After controlling for factors like grade and gender, insufficient physical education courses at school is a risk factor of myopia.