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Background: The onset age of pubertal changes varies widely among girls and has undergone changes over time around the world. This study aimed to determine the age of onset of puberty in healthy Iranian girls living in Isfahan province. Methods: This cross- sectional study was conducted among 13,886 students aged 6–18 years. They were selected by multistage random cluster sampling from urban and rural areas of Isfahan province of Iran. Pubertal stage was determined according the 5-level Tanner stages proposed by Marshall and Tanner. Trained physicians determined the breast development through both visual inspection and palpation, in addition, mothers assessed their daughter's pubic hair growth using Tanner's Sexual Maturation Scale (SMS) by comparison to standard pictures. The data were analyzed by the status quo method. Probit regression analysis was used to evaluate the median age of onset for each characteristic including menarche, breast and pubic hair. Results: A total of 13,886 healthy girls with mean age (SD) of 11.97 (2.9) were studied. Overall 6968 (50.2%) girls experienced menstruation with a median (95%CI) age of 12.05(11.88–12.21) years at its onset. The median age for onset of breast development was 9.89 (95% CI: 9.77 − 10.02) years and for onset of pubic hair development was 10.14 (95% CI: 9.88– 10.39) years. The 3rd percentile for breast stage 2 (B2) and pubic hair stage 2 (PH2) was 6.85 and 6.75 years, respectively, and the 97th percentile for B2 and PH2 was 12.94and 13.54 years, respectively. Conclusion: According to our findings, the onset of puberty before 6.85 years should be considered as precocious puberty for Iranian girls. Our study indicated the secular trend toward earlier menarche in girls. Nationally representative surveys and longitudinal studies are necessary to determine the exact age of puberty for future international comparisons. [ABSTRACT FROM AUTHOR]

Background: Early age at breast development (thelarche) has been associated with increased breast cancer risk. Average age at thelarche has declined over time, but there are few established risk factors for early thelarche. We examined associations between pre- and postnatal exposures and age at thelarche in a US cohort of women born between 1928 and 1974.Methods: Breast cancer-free women ages 35-74 years who had a sister diagnosed with breast cancer were enrolled in the Sister Study from 2003 to 2009 (N = 50,884). At enrollment, participants reported information on early-life exposures and age at thelarche, which we categorized as early (≤ 10 years), average (11-13 years), and late (≥ 14 years). For each exposure, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) for early and late thelarche using polytomous logistic regression, adjusted for birth cohort, race/ethnicity and family income level in childhood.Results: Early thelarche was associated with multiple prenatal exposures: gestational hypertensive disorder (OR = 1.25, 95% CI 1.09-1.43), diethylstilbestrol use (OR = 1.23, 95% CI 1.04-1.45), smoking during pregnancy (OR = 1.20, 95% CI 1.13-1.27), young maternal age (OR 1.30, 95% CI 1.16-1.47 for < 20 vs. 25-29 years), and being firstborn (OR = 1.25, 95% CI 1.17-1.33). Birthweight < 2500 g and soy formula use in infancy were positively associated with both early and late thelarche.Conclusions: Associations between pre- and postnatal exposures and age at thelarche suggest that the early-life environment influences breast development and therefore may also affect breast cancer risk by altering the timing of pubertal breast development. [ABSTRACT FROM AUTHOR]

Objective: Recently, we observed some cases of Precocious Puberty (PP) with a partial central activation of hypothalamic-pituitary-gonadal (HPG) axis that tended to normalized in 6–12 months. To evaluate the frequency of this form within the spectrum of forms of PP, we retrospectively assessed the clinical, hormonal and ultrasound characteristics of patients attending to our Center for signs of PP, between 2007 and 2017. To hypothesize some causes of this "pubertal poussée" a questionnaire about environmental data was provided to patients. Methods: 96 girls were recruited for the study and divided into three Groups. Group 1: 56 subjects with Central PP (CPP) requiring treatment with GnRH analogue; Group 2: 22 subjects with transient activation of pubertal axis, that tended to normalize, "Transient CPP"(T-CPP); Group 3: 18 subjects with Isolated Thelarche (IT). Results: Mean age at diagnosis was 6.8 ± 1.0 years in Group 1, 5.9 ± 1.3 years in Group 2 and 5.6 ± 1.5 years in Group 3. A significant increase of diagnosis of T-CPP was observed over the study period. Significantly higher use of some homeopathic medicines and potential exposure to pesticides was reported in Group 2 vs Group 1. Conclusions: To our knowledge, we first reported a form defined as T-CPP, characterized by partial activation in the HPG axis normalizing over time. An increased use of homeopathic medicines and exposure to environmental pollutants in these patients was evidenced. [ABSTRACT FROM AUTHOR]

Background: Earlier age at menarche is an established risk factor for breast cancer. While age at menarche has been fairly stable over the past half-century, age at breast development (thelarche) has continued to decrease. Recently, earlier age at thelarche and a longer time between thelarche and menarche (pubertal tempo) were shown to be associated with increased breast cancer risk. Our objective was to examine how breast cancer risk was associated with pubertal timing and tempo in a prospective US cohort.Methods: Women ages 35-74 years without a history of breast cancer, but who had a sister previously diagnosed with breast cancer, were enrolled in the Sister Study from 2003 to 2009 (N = 50,884). At enrollment, participants reported their ages at thelarche and menarche. Pubertal tempo was age at menarche minus age at thelarche. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each pubertal milestone and risk of breast cancer (invasive or ductal carcinoma in situ) using Cox proportional hazards regression. We examined whether associations between age at thelarche and breast cancer risk were modified by birth cohort, race/ethnicity, weight at age 10, and extent of breast cancer family history, as characterized by a Bayesian score based on first-degree family structure.Results: During follow-up (mean = 9.3 years), 3295 eligible women were diagnosed with breast cancer. Early ages at thelarche (HR = 1.23, 95% CI 1.03-1.46 for < 10 vs. 12-13 years) and menarche (HR = 1.10, 95% CI 1.01-1.20 for < 12 vs. 12-13 years) were positively associated with breast cancer risk. Pubertal tempo was not associated with breast cancer risk (HR = 0.99, 95% CI 0.97-1.02 per 1-year longer tempo). When considering early thelarche (< 10 years) and early menarche (< 12 years) jointly, women with both had a 30% greater risk of breast cancer compared with women with neither risk factor (95% CI 1.07-1.57). The association between age at thelarche and breast cancer risk did not significantly vary by birth cohort, race/ethnicity, childhood weight, or Bayesian family history score.Conclusions: Earlier ages at thelarche and menarche may enhance susceptibility to breast carcinogenesis. Age at thelarche is an important risk factor to consider given secular trends towards earlier development. [ABSTRACT FROM AUTHOR]