A Survey Of Sex Development Status Among6~12Years Old Children In Urban Suchow And The Relationship Between Puberty Development And Body Fat

Objectives Several recent studies suggest that the timing of the onset of puberty ingirls has become earlier over the past30years,and there is strong evidence that theincreasing rates of obesity in children over the same time period is a major factor.Thisstudy was to investigate the secondary sexual characteristics in urban Suchow childrenbetween6~12years old and to discuss the relationship between puberty development andbody mass index because of body mass index（BMI） is a suitable surrogate for body fat.Methods A study was conducted in urban Suchow including6759boys and6135girls aged in6to12years from October to November in2010.The parents wrote the dateof birth and the past history diseases of chidren.This study examined the secondary sexualcharacteristics and recorded the height and weight.At examination,stages of breast wererated in girls.Data on menses were collected by the status quo method.Testicular volumewas determined with a Prader orchidometer. A testicular volume greater than or equal to4ml was taken as a definite sign of the onset of puberty. Probit analysis was used tocalculate the mean age and95%confidence interval（CI） for onset of breast andtesticular development.For testing of the hypothesis that body fat may have effect onpuberty development each child between the ages of6to12had her/his BMI calculatedand then converted to a BMI Z score. This study examined the data by comparing the BMIz score of children who had the onset of puberty versus those who were still prepubertyand the rate of who had the onset puberty between the normal weight and overweight andobesity.Results Data were analyzed in6134healthy girls and6749healthy boys.The overallcombined prevalence of obesity was11.8%.The incidence of obesity in girls and boyswere11.8%and17.6%,respectively.The mean age of onset of Tanner stages2and3for breast development were10.19（95%CI:10.13~10.24） years and10.83（95%CI:10.77~10.85）years,respectively. The mean age of onset of puberty as indicatedby testicular volume4ml or more was10.88（95%CI:10.80~10.94） years.The incidenceof precocious puberty in female and male students were1.04%and0.81%,respectively.Thewhole incidence was0.9%.For7-to12-year-olds,the mean BMI Z scores of girls withbreast development were greater than for age-matched girls who were prepubertal.Thesame trend was to noted for boys between8to12yeas old.There was a statisticallysiganificant difference at girls in BMI standard deviation scores in prepuberty(p<0.001)during8~11years and at boys in8years old and11years old and12years old.Conclusion The mean height and weight were higher than the national average,butwere similar to the results of shanghai between6to11years old.Body fat may have effecton puberty development in female and the effecet in male is uncertain.