Tracing Analysis Of Pubertal Timing And Related Factors Among Primary And Middle School Students

ObjectiveTo track the current status of pubertal timing and possible related factors of early puberty among primary and middle school students in Zhengzhou City. To explore the association of various factors with pubertal timing and possible gender differences, so as to provide basis for uncovering the mechanism of puberty.MethodsThree schools were selected from urban area in Zhengzhou City. Girls were from Grade 2～3 in the primary schools and Grade 1～3 in the middle schools and boys were from Grade 3～4 in the primary schools and Grade 1～3 in the middle schools. The baseline survey of pubertal development was conducted in October 2014 and the follow-up surveys were conducted in October 2015 and October 2016.In addition, the metabolites of environmental endocrine disruptors in morning urine were measured.Results1. Boys’and girls’ pubertal status tracking The pubic hair development rates of boys aged 8 of the three survey respectively were 0%, 0%, 1% in the baseline survey, and proportions of testicular volume which was no less than 4ml respectively were 5.9%, 12.7%, 56.9%; The pubic hair development rates of boys aged 9 of the three survey respectively were 0%, 2.0%, 11.0%, and proportions of testicular volume which is no less than 4ml respectively were 8%, 17.3%, 75.3%;The pubic hair development rates of boys aged 12 of the three survey respectively were 45.1%, 96.1%, 91.2%, and proportions of testicular volume which is no less than 4ml respectively were 88.2%, 100%, 100%; Among girls aged 7 with menarche occurred in the three survey was 0%, 1.5%, 2.3%, with breast development was 18.2%,48.9%, 100%; Among girls aged 8 with menarche occurred in the three survey was 0%, 0.7%, 9.9% ,with breast development 48.9%,57.4%,80.9%; Among girls aged 12 with menarche occurred in the three survey was 70.0%,92.0%,97.0%,with breast development 100%.2. Boys’ and girls’ pubertal distribution tracking The rates of earlier puberty in the group of boys in the three survey were 17.8%, 17.8%, 20.3%; The rates of earlier puberty in the group of girls in the three survey were 12.1%, 16.1%,21.7%.3. Analysis of pubertal development and physical, body fat index. The starting age of puberty development for boys was related to height,weight,scapular skin-fold thickness and abdominal skin-fold thickness (r=0.609, r=0.343, r=0.209,r=0.170, all P<0.05); the starting age of puberty development for girls was related to height, weight, waist circumference and body fat (r=0.809, r=0.623, r=0.262,r=-0.254, all P<0.05). In the 9-12 age groups of boys, puberty promoters were taller than those in the non puberty group; In 9, 10,12 age groups of boys, puberty promoter were heavier than those in the non puberty group. The average height,weight, waist circumference, Skin-fold thickness of upper arm, scapular skin-fold thickness, and abdominal skin-fold thickness in the same age group for girls in puberty groups were higher than those in the non puberty group (all P<0.05 )4. Analysis of pubertal development and physical activity, daily contact with household chemicals. Boys physical activity scores in the three survey respectively were 12.6±5.9,13.8±6.2,14.6±6.2. Girls physical activity scores respectively were 11.1±5.0,10.7±4.6,11.5±4.8. Boys daily contact with household chemicals scores in the three survey respectively were 2.7±1.9, 2.2±1.7, 2.2±2.5,girls daily contact with household chemicals scores respectively were 2.7±2.0,2.5±1.8,2.6±2.2. Boys food packaging material scores in the three survey respectively were 0.8±1.0, 0.8±1.0,0.7±0.9. Girls physical activity scores respectively were 0.8±1.0, 0.7±1.0, 0.9±1.0. Boys total difficulty scores in the three survey respectively were 7.9±1.8,7.8±1.9,7.9±2.0. Pro-social scores in the three survey respectively were 9.9±4.8,16.4±4.1,16.5±4.1,girls total difficulty scores respectively was 7.2±2.0,7.5±2.0,7.4±2.2,pro-social scores respectively was 17.5±4.0,16.9±4.5,16.9±4.0. physical activity,daily contact with household chemicals, food packaging material, endocrine disrupting chemicals in morning urine, psychological behavior development with the starting age of puberty development were not found correlations, the same to puberty promoter and non puberty promoter.Conclusions1. The same age girl’s breast development rate is higher than menstrual rate. At baseline, the rate of earlier puberty is higher in boys than in girls, the rate of earlier puberty is higher in girls than in boys of the follow-up.2. The average height, weight, waist circumference, Skin-fold thickness of upper arm, scapular skin-fold thickness, abdominal skin-fold thickness,and percentage of body fat in the same age group for girls in puberty groups were higher than those in the non puberty group .3. There is no correlation among physical activity, daily exposure to household chemicals, food packaging materials, endocrine disrupting chemicals in morning urine, and psychological and behavioral development during puberty.