Maternal Age at Menarche and Pubertal Timing in Boys and Girls: A Cohort Study From Chongqing, China

Purpose: This study explored the association of maternal age at menarche (AAM) with pubertal timing among girls and boys in Chongqing, China.

Methods: Pubertal development of 1,237 children (542 girls and 695 boys) were examined half-yearly through inspection and palpation from April 2014 to June 2019. Characteristics of parents and maternal AAM were collected by a parental questionnaire at baseline. Maternal AAM was used both as a continuous and a categorical variable in Cox regression models.

Results: A total of 1,198 children (528 girls and 670 boys) were included in the study. In the simple Cox model, earlier maternal AAM was associated with girls' earlier menarche, breast and pubic hair development, and boys' first ejaculation, testicular development, and genital development. When adjusting for children's body mass index z-scores (BMIz) and socioeconomic covariates, we found that girls whose mothers had early AAM had a higher risk of earlier onset of menarche (hazard ratio [HR]: .922, 95% confidence interval [CI]: .852-.998 for continuous maternal AAM, HR: 1.297, 95% CI: 1.041-1.616 for maternal AAM ≤13 years), and boys whose mother achieved menarche earlier experienced a higher risk of earlier onset of first ejaculation (HR: .896, 95% CI: .830-.968). Children's BMIz were related to all nine pubertal milestones. Parental education and relationship, birth weight, parity, and family type were also associated with pubertal timing.

Conclusions: Earlier maternal AAM was related to earlier pubertal timing in both girls and boys in Chongqing, especially girls' age at menarche and boys' first ejaculation. Children's BMIz was the most consistent factor for pubertal timing. Children's BMIz and socioeconomic conditions had greater influence on most pubertal milestones than maternal AAM.