RESUMO
Objective@#To investigate the effect of maternal passive smoking during pregnancy and girls’ overweight /obesity on the age at menarche(AAM), and to provide a reference for improving healthy development of children and adolescents.@*Methods@#Based on the school entrance physical examination in 2016, a cross-section study was conducted by convenient sampling method, in a total of 2 722 students of 7th grade, from 26 middle schools in urban areas of Guangzhou. Multivariate logistic regression model was used to investigate the relationship between maternal passive smoking during pregnancy and girls’ overweight /obesity and AAM. A four-way decomposition method was used to explore the mediated effect of girls’ overweight/obesity on the relationship between maternal passive smoking during pregnancy and AAM.@*Results@#The proportion of girls who had menstruate was 90.82%(2 472/2 722). The median AAM was 12.00 years old, with an early menarche rate of 34.91%(863/2 472). Compared with girls whose mother hadn’t passive smoking during pregnancy, the risk of early AAM in girls with mother passive smoking during pregnancy≤3 days/week increased by 32%(OR=1.32, 95%CI=1.06-1.65), the risk in girls with maternal passive smoking during pregnancy>3 days/week increased by 58%(OR=1.58, 95%CI=1.21-2.07). Multivariate Logistic regression analysis showed that, overweight or obesity girls had a 77% higher risk of early AAM than non-overweight/obesity girls(OR=1.77, 95%CI=1.36-2.31). The four-way decomposition analysis showed 79.60% of early AAM risk could be accounted by maternal passive smoking during pregnancy(P<0.01).@*Conclusion@#Girls’ overweight/obesity and maternal passive smoking during pregnancy were associated with early menarche. The effect on daughters’ age at menarche is mainly in a direct effect manner of maternal passive smoking during pregnancy.