Early menarche and overweight: evidence from the Italian Health Behaviour School-aged Children Study

BACKGROUND: Globally, the prevalence of obesity has increased in the last years and tends to be higher in richer countries. Overweight (including obesity) interests all the ages, including childhood and adolescence. Our study aimed to investigate the correlation between body mass index (BMI) and age at menarche. METHODS: We used a unique standardized national dataset on adolescent girls (21 regions) participating in the Italian Health Behaviour in School-aged Children Study (HBSC). HBSC is a European surveillance supported by WHO, conducted every 4 years. Two independent nationally representative survey datasets: one on 15-year-olds (n = 6907 year 2017/2018) and one on 11-year-olds (n = 9506 year 2013/2014) were analysed. The survey instrument was the self-report questionnaire. Median age at menarche and 95% confidence intervals (CIs) were estimated by means of Kaplan-Meier analysis. Hierarchical models were used to assess the relationship between BMI and age at menarche (months). “Region-level obesity” was measured as the prevalence of overweight/obesity (%) in each region. We evaluated the relationship with socioeconomic status (SES) through the Family Affluence Scale. RESULTS: Region-level median age at menarche ranged between 12 years/5 months and 13 years/4 months. Region-level prevalence of overweight among 15-year-old girls ranged between 6% and 24%. Age at menarche was inversely associated with individual BMI (unstandardized regression coefficient beta= -0.81; 95% CI, -0.92 to -0.70). Individual and class-level measures of BMI accounted for 215.2% of the region-level variance in age at menarche. The coefficient of Family Affluence differed significantly 0.25 (0.09 to 0.41). CONCLUSIONS: Our results show that being overweighted in pre-adolescence is associated with the early puberty. Strong social inequalities were observed, with adolescents from lower SES are likely to be overweight or obese In line with all the other European countries. KEY MESSAGES: • Weight status can influence menarche. • Policies to reduce socioeconomic inequalities are needed to prevent health problems.