Age of Puberty and Its Relationship with Body Mass Index in Iranian Girls Living in Tabriz

Evaluation of puberty levels in a population requires exact reference values for comparison. This study aimed to determine the age of puberty onset in girls living in Tabriz, Iran and its relation to body mass index (BMI). This cross-sectional study was conducted on 1000 female students, aged 7-17 years, in Tabriz between 2008 and 2009. Participants were selected by multistage random cluster sampling from school students. According to BMI, the participants were divided into 4 groups: obese, overweight, normal weight and underweight. Secondary sexual characteristics were evaluated by inspection and palpation according to Tanner staging. Menarche age, if any, was also recorded. The mean age of puberty onset (breast stage II) was 9.58±1.15 years and the mean age of tanner stage II of pubic hair (P2) was 10.30±1.1 years. The mean age of menarche was 12.58±1.30 years. There was significant difference between the age puberty onset and BMI (P= 0.002). The mean menarche age in the underweight and normal weight groups was significantly greater than overweight and obese groups (14.85 vs 13.81 years, P<0.001). Age of puberty onset is decreasing in our community. This study confirms that obese and overweight girls reach the puberty at a lower age than normal weight girls and their menarche age is less as well.