Age of onset of pubertal characteristics in boys aged 6–14 years of the Province of L’Aquila (Abruzzo, Italy)

Duration of stages of the Middle Phalanx Maturation method in a contemporary population: A 6-year longitudinal analysis

OBJECTIVE

To determine the duration and age at the beginning of each stage corresponding to the circumpubertal period in the Middle Phalanx Maturation method (MPM) and to assess the differences between males and females.

MATERIALS AND METHODS

Sets of X-rays of the middle phalanx of the third finger taken at 6-month intervals were analysed for 246 skeletal Class I subjects (102 females and 144 males) between 9 and 15 years of age. After staging, the duration of each stage was derived from chronological ages, and the difference between males and females for both duration and age at the beginning of each stage was investigated.

RESULTS

The median duration for MPS2 and MPS3 was 1 year for both sexes, while MPS4 showed a median duration of 1 year in females and 9 months in males, with no significant differences between the sexes. Mean age at the beginning of MPS2 was 10y11m for females and 11y11m for males; for MPS3, it was 11y8m for females and 13y1m for males; for MPS4, it was 12y9m for females and 13y11m for males; for MPS5, it was 13y4m for females and 14y3m for males. The differences between the sexes were statistically significant for all the stages (P < .001).

CONCLUSIONS

This study confirms, with relevant sample size, the median duration of 1 year for each MPM stage from MPS2 to MPS4. Despite the distinctive interindividual variability, the interquartile range is 6 months or less for all but one interval, confirming the soundness of the results.

Association of body composition with pubertal timing in children and adolescents from Guangzhou, China

Objective

An ongoing debate surrounds the relationship between body composition and pubertal timing, in particular for boys. This cross-sectional study aimed to investigate the association of body composition with pubertal timing among children and adolescents.

Methods

A total of 1,493 boys and 1,261 girls who entered puberty were enrolled in Guangzhou, China. Tanner stages were evaluated by examination of breast development for girls and testicular volume for boys. Fat mass (FM) and fat-free mass (FFM) were determined by bioelectrical impedance analysis. Parameters for body composition were transformed into age-and gender-specific Z-scores. The association of body composition with pubertal timing was examined using multinomial logistic regression with inverse probability weighting (IPW) based on the propensity score.

Results

For boys, IPW analysis showed Z-scores of body fat percentage (BF%) and FM index (FMI) were negatively associated with early puberty (OR = 0.75, 95% CI = 0.64-0.87; OR = 0.74, 95% CI = 0.63-0.88). As for girls, in contrast to boys, positive associations were seen between BF% and FMI with early puberty (OR = 1.39, 95% CI = 1.19-1.64; OR = 1.59, 95% CI = 1.33-1.90). With respect to appendicular skeletal muscle mass index (ASMI), there was a positive association with early puberty and a negative one with late puberty in boys (OR = 1.26, 95% CI = 1.07-1.49; OR = 0.82, 95% CI = 0.69-0.99).

Conclusion

There is a positive association of FM with early puberty for girls while negative for boys. FFM yields a positive association with early puberty and a negative one with late puberty in boys, but not in girls. Our findings highlight the gender differences in the connection between body composition and pubertal onset.

Overweight/Obesity in Childhood and the Risk of Early Puberty: A Systematic Review and Meta-Analysis

PURPOSE

To determine the relationship between childhood overweight/obesity and early puberty in both boys and girls. Specifically, this is the first time to conduct a meta-analysis of the relationship between childhood overweight/obesity and early puberty in boys.

METHODS

Relevant studies were identified from PubMed, Web of Science, and EMBASE searches. The exposure of interest was overweight/obesity in childhood. Childhood was defined internationally as the age range of 0-18 years. The overall risk estimates were pooled using random effects models. Subgroup and sensitivity analyses were performed to explore possible sources of heterogeneity and to assess the robustness of the results.

RESULTS

A total of 10 studies involving 13,338 girls and 12,796 boys were included. Results showed that childhood overweight/obesity were associated with a significantly higher risk of early puberty in girls [odds ratio (OR): 2.22, 95% CI: 1.65-2.99]. Although without statistical significance, a higher risk of early puberty was also found in boys who were overweight/obese in childhood (OR: 1.29, 95% CI: 0.98-1.70). Heterogeneity in the risk estimates of early puberty was partially explained by study design, sample size, follow-up duration, definitions of early puberty and confounders controlled. Sensitivity analyses validated the robustness of the findings.

CONCLUSIONS

Our findings showed that for girls the associate between overweight/obesity and early puberty is definite or strong whereas for males, such an association is possible, prompting that future studies need to further explore the possible relationship between overweight/obesity and early puberty in boys.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021264649, PROSPERO CRD42021264649.

sCD14 Level in Saliva of Children and Adolescents with and without Dental Caries, a Hurdle Model

Objective: Soluble CD14 (sCD14) plays an important role in the innate immune response of the oral cavity. The investigation of this biomarker for detection of carious lesions is an even more actual procedure due to its non-invasiveness and the ease of withdrawal. The purpose of the present observational case-control study was to evaluate whether the quantification of sCD14 in children and adolescent’s saliva can discriminate healthy subjects from those suffering from tooth decay. Materials and Methods: 164 subjects (6 to 17 years) were selected and divided into 2 groups: those with at least 1 decayed tooth were assigned to group Decayed (n = 82) and those free from dental caries to group Healthy (n = 82). The amount of salivary soluble CD14 was quantified. Results: Mean salivary soluble CD14 was 28.3 ± 10.8 μg/mL in the Healthy group and 22 ± 9.6 μg/mL in the Decayed group. A hurdle model was applied to the data to estimate both the probability of having carious lesions and their number in relation to sCD14 levels. sCD14 was strongly associated (p < 0.01) with an inverse relation to both the probability of having caries and their number (falling rate of 5% per unit CD14 μg/mL). Conclusions: This data confirms the relationship between sCD14 and the presence of dental caries. However, there is no clear cut off level between healthy and unhealthy subjects, so it is currently not possible to use sCD14 as a biomarker to determine the risk of decays.

Connections Between Obesity and Puberty: Invited by Manuel Tena-Sempere, Cordoba

The relationship between obesity and puberty remains controversial. Whereas cross-sectional and longitudinal studies show a clear shift toward earlier puberty in obese girls, the trend in obese boys remains less obvious. Overweight boys mature earlier whereas obese boys mature later compared to healthy weight boys. Newer epidemiologic studies attempt to address these knowledge gaps. This review provides a detailed overview of the recent literature regarding secular trends in pubertal onset and tempo, and the connection with obesity. Additionally, this review summarizes potential mediators that permit obesity to promote early puberty. Other factors such as socioeconomic status, in utero exposures, nutritional, and even endocrine disrupting chemicals can cause perturbation of both metabolism and the endocrine axis that can ultimately have effects on pubertal development.

Reference data for testicular volume measured with ultrasound and pubic hair in Norwegian boys are comparable with Northern European populations

AIM

To estimate references for testicular volume measured with ultrasound and Tanner stages of pubic hair in Norwegian boys, and to compare the timing of puberty with data from similar populations.

METHODS

Testicular volume was derived from ultrasound measurements of testicular volume in a cross-sectional study of 514 healthy boys. A continuous testicular volume for age reference curve was estimated with the LMS method. Tanner stages for pubic hair were clinically assessed in 452 boys. Age references for pubertal milestones were estimated with probit regression.

RESULTS

Puberty onset, defined by an ultrasound testicular volume of 2.7 mL, equivalent to an orchidometer volume of 4 mL, occurred at a mean (SD) age of 11.7 (1.1) years. The reference range was 9.7 (3rd) to 13.7 years (97th percentile). Pubic hair (Tanner stage 2) appeared on average at 11.8 (1.2) years with a corresponding reference range of 9.5-14.1 years.

CONCLUSION

The references for testicular volume measured with ultrasound are continuous in age and allow for the quantification of pubertal development. The age distribution of reaching pubertal milestones was comparable with data from other Northern European countries.

Is there a causal relationship between obesity and puberty?

The onset of puberty in adolescents and whether it is related to obesity is an ongoing topic for debate. Epidemiological cross-sectional and longitudinal studies show a shift towards earlier onset of puberty in girls who are obese; however, the situation is less clear in boys. Boys who are overweight seem to mature earlier, and boys who are obese mature later, than boys at a healthy weight. The underlying mechanisms are not yet fully understood, and whether earlier onset of puberty in obese girls is based on the activation of the hypothalamic-pituitary-gonadal axis is unclear. The most promising link between obesity and puberty is the adipokine leptin and its interaction with the kisspeptin system, which is an important regulator of puberty. However, peripheral action of adipose tissue (eg, via other adipokines, aromatase activity) could also be involved in changes to the onset of puberty. In addition, nutritional factors, epigenetics, or endocrine disrupting chemicals are potential mediators linking the onset of puberty to obesity. This Review summarises our knowledge concerning the relationship between obesity and onset and tempo of puberty, and the consequences of early puberty on obesity.

Pubertal Onset in Apparently Healthy Indian Boys and Impact of Obesity

OBJECTIVE

Primary - to determine the age of pubertal onset in Indian boys. Secondary - (a) to assess the impact of obesity on pubertal timing, (b) to assess the relationship between gonadotropins and puberty.

DESIGN

Cross-sectional.

SETTING

General community-seven schools across New Delhi.

PARTICIPANTS

Random sample of 1306 school boys, aged 6-17 years.

MATERIALS AND METHODS

Anthropometric measurement for weight and height and pubertal staging was performed for all subjects. Body mass index (BMI) was calculated to define overweight/obesity. Serum luteinizing hormone (LH), follicle stimulating hormone, and serum testosterone were measured in every sixth subject.

MAIN OUTCOME MEASURE

Age at pubertal onset-testicular volume ≥4 mL (gonadarche) and pubic hair Stage II.

RESULTS

Median age of attaining gonadarche and pubarche was 10.41 years (95% confidence interval [CI]: 10.2-10.6 years) and 13.60 (95% CI: 13.3-14.0 years), respectively. No significant difference in the age of attainment of gonadarche was observed in boys with normal or raised BMI, though pubarche occurred 8 months earlier in the latter group. Serum gonadotropins and testosterone increased with increasing stages of puberty but were unaffected by BMI. Serum LH level of 1.02 mIU/mL and testosterone level of >0.14 ng/mL showed the best prediction for pubertal onset.

CONCLUSION

The study establishes a secular trend of the age of onset of puberty in Indian boys. Pubarche occurred earlier in overweight/obese boys. The cutoff levels of serum LH and testosterone for prediction of pubertal onset have been established.

Effect of Weight Loss on Puberty Onset in Overweight Children

OBJECTIVE

To assess the impact of weight changes on the onset of puberty in overweight children.

STUDY DESIGN

We evaluated the timing of puberty onset in 160 prepubertal overweight children (aged 11.2 ± 1.0 years) depending on the changes of their weight status in a 1-year lifestyle intervention. We determined body mass index (BMI), pubertal stage, luteinizing hormone (LH), follicle-stimulating hormone, insulin-like growth factor (IGF)-1, insulin-like growth factor binding protein-3, insulin resistance index homeostatic model assessment, and serum gonadotropins at baseline and 1 year later.

RESULTS

Puberty onset during the 1-year follow-up was significantly (P = .014) more frequent in girls without BMI-SDS reduction (75.0%) compared with girls with BMI-SDS reduction (45.7%). The start of puberty was significantly (P = .024) more frequent in boys with BMI-SDS reduction (76.9%) compared with boys without BMI-SDS reduction (53.6%). In logistic regression analyses adjusted for baseline age and BMI-SDS, BMI-SDS reduction was associated with a decreased likelihood for puberty onset in girls (OR 0.24; 95% CI 0.07-0.85) and an increased likelihood in boys (OR 3.77; 95% CI 1.34-10.52). Central onset of puberty was confirmed by an increase of LH concentration and LH/follicle-stimulating hormone ratio in both boys and girls. Homeostatic model assessment, IGF-1, and IGF-1/insulin-like growth factor binding protein-3 ratio as marker for free IGF-1 at baseline or their changes were not associated with the onset of puberty.

CONCLUSIONS

BMI-SDS reduction in overweight children was associated with earlier gonadotropin-dependent onset of puberty in boys and later onset of puberty in girls, suggesting earlier puberty in obese girls and later puberty in obese boys. We found no evidence that insulin resistance or IGF-1 have an impact on the start of puberty in obese children.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00435734.

Adiponectin/resistin levels and insulin resistance in children: a four country comparison study

Background

There are few reports on the effects of ethnicity or gender in the association between adipocytokines and insulin resistance in children of different ages. This study assessed associations between serum concentrations of adiponectin/resistin and parameters of insulin resistance in children from 4 different countries.

Methods

A total of 2,290 children were analyzed in this study; each was from one of 4 different countries (Japan, Thailand, Italy and USA), and grouped according to age (8–11 years old in Group 1 and 12–15 years old in Group 2).

Results

Adioponectin was higher in female than in male children, and in Group 1 than in Group 2. Generally, adiponectin was lower in Asian as compared to Italian and American children. These tendencies remained even after adjustment for body mass index (BMI) or waist circumstance (WC). Among older children (Group 2), resistin was higher in female than in male children. Significant correlations by non-parametric univariate correlation coefficients and Spearman’s rank correlation coefficients were found between adiponectin and homeostasis model assessment of insulin resistance (HOMA-IR), and fasting serum insulin levels in young Japanese, Italian, and American female children(p < 0.01, p < 0.05, p < 0.05, respectively). Correlations between serum adiponectin and HOMA-IR were also found among older male Italian, American, and Thai children (p < 0.05, p < 0.001, p < 0.001, respectively). In multiple regression analysis by forced entry method, adiponectin correlated with HOMA-IR in Italian and American male children, and in all older female children regardless of country of origin. There was no correlation between resistin and markers of insulin resistance in children from any of the countries.

Conclusions

We conclude that serum adiponectin concentrations are lower in Asian as compared to Italian and American children, and that adiponectin but not resistin contributes to differences in markers for insulin resistance in children from different populations.

Changing age of acne vulgaris visits: another sign of earlier puberty?

The objective of the current study was to assess changes in the onset of pubertal maturation by determining whether acne is occurring at an earlier age. We assessed the age at which acne is occurring by assessing trends in the age of people seeking medical attention for acne. The National Ambulatory Medical Care Survey database was used to analyze physician visits for acne vulgaris in children aged 6 to 18 from 1979 to 2007. The data were used to assess trends in the mean age of children with acne and to compare these trends according to race and sex. Regression analysis revealed a significant decrease in the mean age of children seeking treatment for acne over this 28-year period (p < 0.001). There was no significant change in the mean age of black children seeking treatment for acne. Black girls had the lowest mean age whereas white boys had the highest mean age. There has been a decrease in the average age of children seeking treatment for acne that may be indicative of earlier acne onset. This finding provides supporting evidence of the increasingly earlier onset of puberty in girls.

Timing of maturation and predictors of Tanner stage transitions in boys enrolled in a contemporary British cohort

This study describes the timing of puberty in 8- to 14-year-old boys enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) and identifies factors associated with earlier achievement of advanced pubic hair stages. Women were enrolled during pregnancy and their offspring were followed prospectively. We analysed self-reported pubic hair Tanner staging collected annually. We used survival models to estimate median age of attainment of pubic hair stage >1, stage >2 and stage >3 of pubic hair development. We also constructed multivariable logistic regression models to identify factors associated with earlier achievement of pubic hair stages. Approximately 5% of the boys reported Tanner pubic hair stage >1 at age 8; 99% of boys were at stage >1 by age 14. The estimated median ages of entry into stages of pubic hair development were 11.4 years [95% confidence interval (CI) 11.3, 11.4] for stage >1, 12.7 years [95% CI 12.7, 12.8] for stage >2 and 13.5 years [95% CI 13.5, 13.6] for stage >3. Predictors of younger age at Tanner stage >1 included low birthweight, younger maternal age at delivery and being taller at age 8. Associations were found between younger age at attainment of stage >2 and gestational diabetes and taller or heavier body size at age 8. Being taller or heavier at age 8 also predicted younger age at Tanner stage >3. The results give added support to the strong influence of pre-adolescent body size on male pubertal development; the tallest and heaviest boys at 8 years achieved each stage earlier and the shortest boys later. Age at attainment of pubic hair Tanner stages in the ALSPAC cohort are similar to ages reported in other European studies that were conducted during overlapping time periods. This cohort will continue to be followed for maturational information until age 17.

Hypothesis: exposure to endocrine-disrupting chemicals may interfere with timing of puberty

A recent decline in onset of puberty - especially among girls - has been observed, first in the US in the mid-1990s and now also in Europe. The development of breast tissue in girls occurs at a much younger age and the incidence of precocious puberty (PP) is increasing. Genetic factors and increasing prevalence of adiposity may contribute, but environmental factors are also likely to be involved. In particular, the widespread presence of endocrine-disrupting chemicals (EDCs) is suspected to contribute to the trend of earlier pubertal onset. The factors regulating the physiological onset of normal puberty are poorly understood. This hampers investigation of the possible role of environmental influences. There are many types of EDCs. One chemical may have more than one mode of action and the effects may depend on dose and duration of the exposure, as well as the developmental stage of the exposed individual. There may also be a wide range of genetic susceptibility to EDCs. Human exposure scenarios are complex and our knowledge about effects of mixtures of EDCs is limited. Importantly, the consequences of an exposure may not be apparent at the actual time of exposure, but may manifest later in life. Most known EDCs have oestrogenic and/or anti-androgenic actions and only few have androgenic or anti-oestrogenic effects. Thus, it appears plausible that they interfere with normal onset of puberty. The age at menarche has only declined by a few months whereas the age at breast development has declined by 1 year; thus, the time span from initiation of breast development to menarche has increased. This may indicate an oestrogen-like effect without concomitant central activation of the hypothalamic-pituitary axis. The effects may differ between boys and girls, as there are sex differences in age at onset of puberty, hormonal profiles and prevalence of precocius puberty.

Recent decline in age at breast development: the Copenhagen Puberty Study

OBJECTIVE

Recent publications showing unexpectedly early breast development in American girls created debate worldwide. However, secular trend analyses are often limited by poor data comparability among studies performed by different researchers in different time periods and populations. Here we present new European data systematically collected from the same region and by 1 research group at the beginning and end of the recent 15-year period.

METHODS

Girls (N = 2095) aged 5.6 to 20.0 years were studied in 1991-1993 (1991 cohort; n = 1100) and 2006-2008 (2006 cohort; n = 995). All girls were evaluated by palpation of glandular breast, measurement of height and weight, and blood sampling (for estradiol, luteinizing hormone, and follicle-stimulating hormone). Age distribution at entering pubertal breast stages 2 through 5, pubic hair stages 2 through 5, and menarche was estimated for the 2 cohorts.

RESULTS

Onset of puberty, defined as mean estimated age at attainment of glandular breast tissue (Tanner breast stage 2+), occurred significantly earlier in the 2006 cohort (estimated mean age: 9.86 years) when compared with the 1991 cohort (estimated mean age: 10.88 years). The difference remained significant after adjustment for BMI. Estimated ages at menarche were 13.42 and 13.13 years in the 1991 and 2006 cohorts, respectively. Serum follicle-stimulating hormone and luteinizing hormone did not differ between the 2 cohorts at any age interval, whereas significantly lower estradiol levels were found in 8- to 10-year-old girls from the 2006 cohort compared with similarly aged girls from the 1991 cohort.

CONCLUSIONS

We found significantly earlier breast development among girls born more recently. Alterations in reproductive hormones and BMI did not explain these marked changes, which suggests that other factors yet to be identified may be involved.

Pubertal development of Turkish children

AIM

To investigate the pubertal development of Turkish school children, to look for possible secular trends in pubertal development.

METHODS

1,562 girls and 1,749 boys (aged 6-16.5 years) from urban and rural schools were studied. Weight and height were measured and body mass index was calculated. Pubertal stages were assessed according to Tanner. Testicular volume was determined using an orchidometer. Menarcheal age was recorded.

RESULTS

In girls, mean ages at breast stage (B) were 7.74 +/- 1.08 years for B1, 10.16 +/- 0.97 for B2, 11.72 +/- 1.29 for B3, 12.97 +/- 1.17 for B4, and 13.66 +/- 0.89 for B5. Mean ages at pubic hair stage (PH) were 8.72 +/- 1.50 years for PH1, 10.57 +/- 1.39 for PH2, 12.12 +/- 1.10 for PH3, 13.10 +/- 1.04 for PH4, and 13.87 +/- 0.83 for PH5. Mean age at menarche was 12.41 years. Menarcheal age was earlier in overweight and obese children compared with that in normal children. In boys, mean ages at each maturity stage according to testis volume (G) were 8.70 +/- 1.38 years for G1, 11.76 +/- 1.28 for G2, 12.81 +/- 1.0 for G3, 13.17 +/- 0.87 for G4, and 13.87 +/- 0.98 for G5. Mean ages at PH in boys were 9.39 +/- 1.81 years for PH1, 12.02 +/- 1.33 for PH2, 13.05 +/- 0.88 for PH3, 13.42 +/- 0.87 for PH4, and 14.02 +/- 0.92 for PH5.

CONCLUSIONS

The current study provides an up-to-date reference of normal sexual maturation of Turkish children. While the mean age at onset of puberty in boys was comparable to that of other populations in the world, girls were found to start pubertal development earlier than in other populations.

Gender-related differences in the relationships between blood pressure, age, and body size in prepubertal children

BACKGROUND

The blood pressure (BP) increase with age is well documented in adults and children. However, in the pediatric age group, body size is the most important determinant of age-related BP increases. The aim of the present analysis was to investigate the relationships between age, gender, and body size and BP in children.

METHODS

To this purpose, data were analyzed from 4,514 prepubertal children, aged 6-11 years (71% of the eligible sample; boys = 2,283, girls = 2,231) from the ARCA Project, a screening of childhood obesity carried out in southern Italy. Girls who reported the occurrence of menarche were excluded from the analysis. The sample constituted roughly 20% of all the children attending the primary schools in the area. Weight, height, waist circumference, and BP were measured according to standardized procedures.

RESULTS

As expected, both systolic and diastolic BP significantly increased (P < 0.001) with age in boys and girls. However, after adjustment for waist circumference (as index of adiposity) and height (as index of body size), BP significantly increased with age only in girls (systolic BP: F = 4.380, P = 0.002; diastolic BP: F = 3.093, P = 0.01) but not in boys (systolic BP: F = 0.711, P = 0.55; diastolic BP: F = 2.180, P = 0.07). The association, however, was no longer apparent after the exclusion of children aged >10 years.

CONCLUSIONS

In prepubertal girls in the age range 6-11 years, but not in boys, age is significantly associated with BP independently of body size and adiposity.

The sensitivity of the child to sex steroids: possible impact of exogenous estrogens

The current trends of increasing incidences of testis, breast and prostate cancers are poorly understood, although it is assumed that sex hormones play a role. Disrupted sex hormone action is also believed to be involved in the increased occurrence of genital abnormalities among newborn boys and precocious puberty in girls. In this article, recent literature on sex steroid levels and their physiological roles during childhood is reviewed. It is concluded that (i) circulating levels of estradiol in prepubertal children are lower than originally claimed; (ii) children are extremely sensitive to estradiol and may respond with increased growth and/or breast development even at serum levels below the current detection limits; (iii) no threshold has been established, below which no hormonal effects can be seen in children exposed to exogenous steroids or endocrine disruptors; (iv) changes in hormone levels during fetal and prepubertal development may have severe effects in adult life and (v) the daily production rates of sex steroids in children estimated by the Food and Drug Administration in 1999 and still used in risk assessments are highly overestimated and should be revised. Because no lower threshold for estrogenic action has been established, caution should be taken to avoid unnecessary exposure of fetuses and children to exogenous sex steroids and endocrine disruptors, even at very low levels.

Pubertal development in Danish children: comparison of recent European and US data

Two recent epidemiological studies (PROS and NHANES III) from the USA noted earlier sexual maturation in girls, leading to increased attention internationally to the age at onset of puberty. We studied the timing of puberty in a large cohort of healthy Danish children in order to evaluate differences between USA and Denmark, as well as to look for possible secular trends in pubertal development. Healthy Caucasian children from public schools in Denmark participated in the study which was carried out in 1991-1993. A total number of 826 boys and 1,100 girls (aged 6.0-19.9 years) were included, and pubertal stages were assessed by clinical examination according to methods of Tanner. In boys testicular volume was determined using an orchidometer. We found that age at breast development 2 (B2) was 10.88 years, and mean menarcheal age was 13.42 years. Girls with body mass index (BMI) above the median had significantly earlier puberty (age at B2 10.42 years) compared with girls with BMI below the median (age at B2 11.24 years, p < 0.0001). Similarly, menarcheal age was significantly lower in girls with BMI above the median compared with girls with BMI below the median (13.12 vs. 13.70 years, p = 0.0012). In Danish boys we found that age at genital stage 2 (G2) was 11.83 years. Both sexes were significantly taller compared with data from 1964, but timing of pubertal maturation seemed unaltered. Finally, puberty occurred much later in Denmark compared with recent data from USA. We could not detect any downwards secular trend in the timing of puberty in Denmark between 1964 and 1991-1993 as seen in the US. Obesity certainly plays a role in the timing of puberty, but the marked differences between Denmark and USA cannot be attributed exclusively to differences in BMI. A possible role of other factors like genetic polymorphisms, nutrition, physical activity or endocrine disrupting chemicals must therefore also be considered. Therefore, we believe it is crucial to monitor the pubertal development closely in Denmark in the coming decades.