The prevalence and risk factors of premature thelarche and pubarche in 4- to 8-year-old girls.

To assess the prevalence of premature thelarche (PT) and pubarche in healthy 4- to 8-year-old girls and to investigate factors associated with early pubertal development.Eight hundred and twenty girls were examined by two paediatric endocrinologists to determine Tanner staging. The effects of body mass index, gestational age, intrauterine growth status, age at the first tooth eruption, socio-economical status, maternal age of menarche and consumption of certain food items on early pubertal development were analysed through parametric and nonparametric tests.The prevalence of PT and of premature pubarche was 8.9% and 4.3%, respectively. We found a strong association between the prevalence of PT and the body mass index standard deviation scores (BMI SDS). There were more girls with BMI SDS values above 1 in the PT group (56.1%) than among the remaining subjects (22.9%). Premature thelarche was not significantly associated with intrauterine growth, premature birth, socioeconomic status, age of first tooth eruption or maternal age of menarche. Similarly, the amount of milk, eggs, chicken or fish consumed was not associated with PT. None of the investigated factors were associated with premature pubarche.Occurrence of PT is strongly associated with BMI SDS. Studies investigating secular trends in pubertal development must consider a secular change in body mass index.