Background: Early puberty has been associated with various adverse health outcomes. We aimed to characterize the spatiotemporal patterns of age at menarche or spermarche in China and to identify potential associated factors. Methods: We leveraged data from six consecutive nation-wide cross-sectional surveys in China conducted in 1995, 2000, 2005, 2010, 2014, and 2019. A total of 519 940 girls aged 9 to 18 years and 392 813 boys aged 11 to 18 years from 30 provinces in Mainland China were included. Probabilistic analysis was used to estimate the median ages at spermarche or menarche as surrogate measures of pubertal development. We used Bayesian spatiotemporally varying series models with the spatiotemporal variance partitioning index to assess the spatiotemporal heterogeneity of ages at menarche or spermarche across 30 provinces and to quantify the relative contributions of the socioeconomic and environmental factors. Results: Almost all provinces experienced decreases in the median ages at spermarche and menarche during the study period. Regional disparities were identified, as a faster decreasing trend was generally observed in eastern provinces when compared with western provinces. Socioeconomic factors explained 34.58% of the spatiotemporal heterogeneity for boys and 34.17% for girls, while environmental factors explained 55.68 and 56.22%, respectively. Among these, temperature, nighttime light, nitrogen dioxide, relative humidity, and illiteracy rate showed the largest contributions (each >5%). In general, higher levels of economic indicators and environmental stressors were observed in provinces with lower initial ages at spermarche and menarche and/or faster declining trends. Conclusions: A significant trend toward early puberty was observed in China over the past 25 years, especially in eastern provinces. Both socioeconomic and environmental factors were strongly associated with the observed spatiotemporal patterns.
Hao et al. (Wed,) studied this question.