Weight status is associated with puberty timing in girls in Isfahan province, Iran

This study aimed to examine how Body Mass Index (BMI) influences the timing of puberty in girls.

This cross-sectional study included students from urban and rural areas of Isfahan Province, Iran. Breast development was assessed by visual inspection and palpation and pubic hair development was evaluated using Tanner's Sexual Maturation Scale. Participants reported the month and year of menarche. Median ages for each pubertal stage were estimated using probit modelling, and analyses were performed separately by BMI category (underweight, normal weight, overweight and obese).

A total of 13 886 girls aged 6-18 years participated. According to WHO cut-offs, 61.9% were normal weight, 9.5% underweight, 13.1% overweight, 15.5% obese and 50.2% had experienced menarche. The onset of breast development (≥B2) occurred earliest in overweight (9.59 years) and obese (9.68 years) girls, followed by normal-weight (9.87 years) and underweight (10.61 years) participants. A similar trend was observed across subsequent Tanner stages and pubic hair development. Median age at menarche was 11.62 years in obese girls, 11.76 years in overweight, 12.04 years in normal-weight and 13.15 years in underweight participants. Overall, girls with higher BMI reached pubertal milestones and menarche earlier than their normal-weight and underweight peers.

Higher BMI in girls is associated with earlier onset of puberty and menarche. These findings highlight the impact of childhood overweight and obesity on pubertal development and underscore the importance of monitoring growth and weight status to anticipate and manage potential health consequences.