Defining Pubertal Timing In Chinese Children: National Standard And Applied Research

Objective To establish age-and sex-specific national norm of pubertal milestone events inrepresentiative children and adolescents in China, and to provide age references for normaloff-time pubertal timing. The study also aims to explore adverse psychological effects ofoff-time puberty and underlying neurobiological mechanisms.Methods Participants of study one and study two all came from urban and rural areas ineight research sites inlcuding Northeast (Shenyang in Liaoning province), North China(Tianjin), East China (Shanghai, Hefei in Anhui province), Central China (Wuhan in Hubeiprovince, Zhengzhou in Henan province), Southwest (Chongqing), South China (Guangzhouin Guangdong province). By cluster sampling, all the Han nationality students aged6.0~18.9years from grade one to grade12in the selected schools participated in this investigation.Anthropometry indices (height and weight), secondary sexual characteristics (breast for girls,genital and testicular volume for boys and pubic hair for both boys and girls) were examinedby trained physicians. Children Depression Inventory (CDI) were used to assess depressivesymptoms. Three types of pubertal timing assessment methods, which was objectiveassessment by pubertal sexual characteristics, subjective assessment by scores of PDS(Pubertal Development Scale) and by self-perceived compared with peers, respectively, wereused and correlated with depressive symptoms. Participants of Study three were recruitedfrom one center elementary school in Bengbu, Anhui Province. Both antropometry andpuberty examination were conducted together with questionnaire survey. Fifty-six girls withearly puberty assessed through objective method and the age-(±2months), BMI (±0.2kg/m2), class-matched girls with normal puberty were implemented with Groningen SocialStress Test (GSST). Four salivary samples were collected to calculated area under the curvewith respect to the increase (AUCi).Results Age-and sex-specific pubertal development age norm were established among30399Han nationality children and adolescents aged6.0~18.9years from8areas throughout China, including15011boys and15388girls. The median ages at stage2for genital andbreast development, testicular volume more than3ml (TV>3ml) and menarcheal age were11.24years,9.18years,11.02years and12.43years. The median ages at stage2for pubichair growth were12.67years in boys and11.65years in girls. Children and adolescents withBMI≥85th percentile had earlier age for puberty development compared with girls with BMI<85th percentile. Age of pubertal onset in urban boys was significantly lower than rural boys.Different effects on depressive symptoms of off-time pubertal timing were found in subjectiveand objective pubertal timing assessment method. Significant correlations with depressivesymptoms were found in early puberty girls assessed by two subjective methods (based onPDS scores and self perception). Risk of depressive symptoms was higher in early pubertyboys than normal puberty peers, and the effects were more obvious during early adolescence.Self-perceived early puberty and late puberty increased depressive symptoms significantly inboth boys and girls.Girls with EP had higher C2, C3and AUC increment (AUCi) compared to NO-EP girls.Depressive symptoms correlated with lower AUCi in salivary cortisol among girls with EP.This study demonstrated the disturbance effect of objectively examined early pubertal timingon HPA axis responses, which might add to vulnerability to psychopathology among earlypuberty girls. It also suggested that stress reactivity might be blunted for individuals withdepressive symptoms.Conclusions The age range and percentiles of key pubertal milestones available from thisstudy could be used as standards for pubertal timing among Chinese children and adolescentsat present. Our findings provide some evidence that there is an obvious early pubertal onsetand relatively slow progression pattern in Chilnese children and adolescents. Self-perceiveearly and late puberty were both risk factors for depressive symptos among Chinese boys andgirls. This study also demonstrated the disturbance effect of objectively examined earlypubertal timing on HPA axis responses, which might add to vulnerability to psychopathologyamong early puberty girls.