Relationship Between Body Fat Percentage And Early Puberty In Girls Aged 6-9 In Zhongshan,Guangdong

BackgroundIn recent years,studies of Chinese children and adolescents have found that the prevalence of overweight and obesity is increasing.At the same time,the prevalence of precocious puberty in girls is increasing,There is a parallel upward trend between the prevalence of overweight and obesity and the prevalence of precocious puberty.Many studies have found that the obesity of female is a risk factor for precocious puberty.However,most relevant studies use body mass index(BMI)as a criterion for judging overweight and obesity.However,compared with BMI,body fat percentage(BF%)can directly distinguish adipose tissue and is more helpful in predicting metabolic disease risk.Therefore,analyzing the relationship between BF%and early puberty is more helpful for judging the relationship between overweight and obesity and puberty,and for prediction of the risk of puberty-related diseases.ObjectiveTo analyze the relationship between BF%and early puberty in girls aged 6-9,comparing the correlation between BF%and BMI,weight,waist circumference(WC),waist-to-height ratio(WHtR),estradiol(E2),follicle-stimulating hormone(FSH),luteinizing hormone(LH).And the BF%percentile curve of girls aged 6-9 years was fitted to judge the change trend of BF%with age.MethodsThis study was a cross-sectional study conducted in Zhongshan City,Guangdong Province,as part of a baseline survey of a multicenter prospective cohort study of the National Nature Project.The baseline survey adopted the method of multi-level stratified cluster random sampling,and finally included 6696 students in grades 1 to 3 from 9 schools.Anthropometric and pubertal developmental assessments were performed by trained pediatricians,BF%was measured using bioelectrical impedance analysis,and fasting blood samples were collected for E2,LH,and FSH levels.This study only analyzed some of these children,so the population was screened according to the exclusion criteria.All boys,children who used drugs or had related diseases that affect growth and development,and children who lacked the necessary data for the study were excluded 407 girls.Children were divided into normal puberty group and early puberty group according to their puberty status,and early puberty was defined as the median age of children whose age is less than the current puberty status.Mann-Whitney U test and Pearson’s chi-square test or Fisher’s exact test were used to compare the differences between groups for continuous variables and categorical variables,respectively;Logistic regression analysis was used to analyze the influencing factors of obesity on early puberty;Spearman correlation analysis was used to compare the correlations between BF%and anthropometric measures,sex hormones;and percentile curves of BF%in girls aged 6-9 years were fitted using the LMS method.Data analysis was performed using SPSS and R language software.ResultIn the same age group,the anthropometric data(such as BMI,weight,waist circumference,etc.)of the girls in the early puberty group were higher than those in the normal puberty group(p<0.001),and their BF%(24.80%)was higher than that in the normal development group(16.65%).Girls who living in townships and attending private schools had a higher prevalence of early development(p<0.001).Elevated BF%was a risk factor for early puberty in girls(OR=1.138,95%Cl=1.046-1.237),and BF%was significantly positively correlated with BMI,weight,and waist circumference(r=0.686,0.875,0.753),but was not correlated with E2,FSH and LH levels.In addition,the BF%of girls aged 6-9 increased with age,and calculated at the 50th percentile,the increase was about 19.93%.Conclusion1.Increased body fat percentage is a risk factor for early puberty in girls.2.There is a significant positive correlation between body fat percentage and BMI,weight and waist circumference in girls.3.The BF%of girls aged 6-9 increases with age.