Association Between Unhealthy Family Structure With Early Puberty Timing In Children

Objective: To investigate the status of family structure, puberty timing and relevant factors of early puberty timing in children of urban primary schools in Chongqing;to establish a prospective and retrospective cohort study in order to trace the onset and process of puberty; and to explore the association between unhealthy family structure with early puberty timing.Methods: According to the purposive sample method, four representative urban primary schools in Jiulongpo District, Chongqing, were selected and of which students from grade one to four who have obtained written informed consent were recruited in our study. Questionnaire survey on social-demographic characteristics and family environment, Pubertal Development Scale(PDS) survey and physical examination were conducted. Target children including exposed group(unhealthy family structure) and non-exposed group(good family structure) were chosen from the baseline survey. Pubertal events and their time of occurrence were retrospected in children who had entered into puberty. A total of three follow-up surveys with frequency of once every six months were conducted in all children.Results: 1237 children including 695 boys and 542 girls were investigated in the baseline survey with the rate of written informed consent was 50.1%. The proportion of unhealthy family structure was 51.1% among all investigated children. The detection rate of early puberty timing was 16.9% according to the score of PDS,with a significant difference between boys and girls(14.5% vs 20.0%, χ2=6.578, P=0.010). The median ages of Tanner stages Ⅱ of testicular and breast development were 11.51 and 10.43 years old respectively. Multivariate logistic regression showed that obesity(OR=1.874, 95%CI:1.101~3.189), maternal age of menarche(OR=0.940, 95%CI:0.885~0.997), low birth weight(OR=4.236, 95%CI:1.645~10.906) and gender(OR=0.635, 95%CI:0.444~0.908) were relevant factors of early puberty timing in all chlidren. Poor subjective economic status(OR=2.195,95%CI:1.275~3.780;OR=3.167, 95%CI:1.068~9.387), floating children(OR=0.558,95%CI:0.139~0.978), history of medicine to accelerate the growth and development(OR=13.361, 95%CI:1.289~138.529) and low birth weight(OR=6.296,95%CI:1.429~27.734) were relevant factors of early puberty timing in boys, while obesity(OR=3.356,95%CI:1.028~2.762), maternal age of menarche(OR=0.867,95%CI:0.787~0.955), eating food with high hormone(OR=0.410,95%CI:0.232~0.725) were relevant factors of early puberty timing in girls.All the children(n=1237) in the baseline survey were eligible for the cohort study, of whom, 605 were in good family structure group and 632 were inunhealthy family structure group. 19 children were lost in our follow-up survey and the lost rate was 1.5%. There was good comparability between two groups, except for father’s education level(χ2=9.040,P=0.029) and relationship between parents(χ2=16.290,P=0.000). The follow up results showed that the median ages of Tanner stages Ⅱ of testicular and breast development were 10.65 and 9.81 years old respectively. The detection rate of early puberty timing was 10.1% with a significant difference between boys and girls(5.6% vs 15.9%, χ2=35.259, P=0.000). The detection rate of precocious puberty was 2.4%, of which, that in boys was 2.1% and that in girls was 3.1%. Cox regression showed that there was no significant difference in puberty development between unhealthy and good family structure and other relevant factors(P>0.05). Survival curves showed that pubertal onset of children with unhealthy family structure were earlier than children with good family structure, of which, boys who were being left-behind or whose parents had divorced were earlier than boys without these conditions, while that of boys who were being floating or whose parents had died were later than boys without these conditions. Meanwhile, pubertal onset of girls who were floating or being left-behind or whose parents had died were earlier than girls without these conditions, while that of girls whose parents had divorced were later than girls without this conditions.Conclusion: Unhealthy family structure in urban Chongqing is an outstanding phenomenon. The dection rate of early puberty is relatively low and early onset of puberty in urban Chongqing still exists. Obesity, early maternal age of menarche, low birth weight and gender were relevant factors of early puberty timing in all children. There are significant gender differences in the relevant factors of early puberty timing. Unhealthy family structure might be correlated with early puberty timing and the correlation between boys and girls might be different. Further follow-ups are needed to observe the onset and process of puberty development, and to estimate the real dection rate of early puberty timing, and to confirm the correlation between unhealthy family structure and early puberty timing.