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

The Effect of Bisphenol A on Puberty: A Critical Review of the Medical Literature

Many scientific studies have revealed a trend towards an earlier onset of puberty and have disclosed an increasing number of children that display precocious puberty. As an explanation, some authors have considered the global socio-economic improvement across different populations, and other authors have considered the action of endocrine disrupting chemicals (EDCs). Among these, bisphenol A (BPA), an aromatic compound largely used worldwide as a precursor of some plastics and chemical additives, is well known for its molecular oestrogen-like and obesogenic actions. We reviewed the medical literature of the previous 20 years that examined associations between BPA exposure and the age of puberty in humans, considering only those referring to clinical or epidemiological data. Of 19 studies, only 7 showed a correlation between BPA and puberty. In particular, the possible disruptive role of BPA on puberty may be seen in those with central precocious puberty or isolated premature breast development aged 2 months to 4 years old, even if the mechanism is undefined. Some studies also found a close relationship between urinary BPA, body weight, and early puberty, which can be explained by the obesogenic effect of BPA itself. The currently available data do not allow establishment of a clear role for BPA in pubertal development because of the conflicting results among all clinical and epidemiological studies examined. Further research is needed to fully understand the potential role of exposure to EDCs and their adverse endocrine health outcomes.

The mystery of puberty initiation: genetics and epigenetics of idiopathic central precocious puberty (ICPP)

Puberty is a major developmental stage. Damaging mutations, considered as "mistakes of nature", have contributed to the unraveling of the networks implicated in the normal initiation of puberty. Genes involved in the abnormal hypothalamic-pituitary-gonadal (HPG) axis development, in the normosmic idiopathic hypogonadotropic hypogonadism (nIHH), in the X-linked or autosomal forms of Kallmann syndrome and in precocious puberty have been identified (GNRH1, GNRHR, KISS1, GPR54, FGFR1, FGF8, PROK2, PROKR2, TAC3, TACR3, KAL1, PROK2, PROKR2, CHD7, LEP, LEPR, PC1, DAX1, SF-1, HESX-1, LHX3, PROP-1). Most of them were found to play critical roles in HPG axis development and regulation, the embryonic GnRH neuronal migration and secretion, the regulation and action of the hypothalamic GnRH. However, the specific neural and molecular mechanisms triggering GnRH secretion remain one of the scientific enigmas. Although GnRH neurons are probably capable of autonomously generating oscillations, many gonadal steroid-dependent and -independent mechanisms have also been proposed. It is now well proven that the secretion of GnRH is regulated by kisspeptin as well as by permissive or opposing signals mediated by neurokinin B and dynorphin. These three supra-GnRH regulators compose the kisspeptin-neurokinin B-dynorphin neuronal (KNDy) system, a key player in pubertal onset and progression. Moreover, an ongoing increasing number of inhibitory, stimulatory and permissive networks acting upstream on GnRH neurons, such as GABA, NPY, LIN28B, MKRN3 and others integrate diverse hormonal and peripheral signals and have been proposed as the "gate-keepers" of puberty, while epigenetic modifications play also an important role in puberty initiation.

Secular trends in the timing of skeletal maturation as assessed by the cervical vertebrae maturation method

Objective

To investigate the presence of secular trends in skeletal maturation of girls and boys as assessed by the use of cervical vertebrae bones.

Materials and methods

The study compared two main groups: the first included data collected from the Denver growth study (1930s to 1960s) and the second included data collected from recent pretreatment records (1980s to 2010s) of patients from the orthodontic clinic of a North American University. The records from the two groups were all for Caucasian subjects. The sample for each group included 78 lateral cephalographs for girls and the same number for boys. The age of the subjects ranged from 7 to 18 years. Cervical vertebrae maturation (CVM) stages were directly assessed from the radiographs according to the method described by Hassel and Farman in which six CVM stages were designated from cervical vertebrae 2, 3, and 4.

Results

The mean age of girls from the Denver growth study and girls from the university clinic in each of the six CVM stages was not different at P ≤0.05. However, the mean age of boys from the two groups was not different only in stage 3 (P = 0.139) and stage 4 (P = 0.211).

Conclusions

The results showed no evidence to indicate a tendency for earlier skeletal maturation of girls or boys. Boys in the university group started their skeletal maturation later than boys in the Denver group and completed their maturation earlier. Gender was a significant factor affecting skeletal maturation stages in both Denver and university groups.

High DHEAS Is Associated With Earlier Pubertal Events in Girls But Not in Boys

Context:

Premature adrenarche (PA) has been associated with increased metabolic risk.

Objective:

To describe the risk of precocious thelarche (PT; <8 years), pubarche (PP; girls <8 years, boys <9 years), and gonadarche (PG; <9 years) in children with high dehydroepiandrosterone sulphate (DHEAS [HD]) vs those with normal DHEAS (ND).

Setting and Intervention:

Longitudinal Chilean cohort (n = 1052, 49.9% girls). Annual clinical examination including secondary sex characteristics by Tanner staging. Logistic regression models were adjusted by age and BMI.

Main Outcome:

Assess the relationship between DHEAS and premature thelarche, gonadarche, and pubarche in both sexes.

Results:

At age of DHEAS determination, overweight/obesity was present in 44.3% of boys and 42.9% of girls. Incidences of any precocious event were observed in 17.2% of boys and in 25.4% of girls, presented as 8.7% of PG and 8.5% of PP in boys and as 21.3% of PT and 4.1% of PP in girls. In crude and adjusted models in boys, HD did not increase the risk of earlier pubertal events. Conversely, girls with HD had a 2.6 times greater risk of early thelarche and a three times greater risk of early pubarche compared with girls with ND concentrations.

Conclusion:

In Chilean adolescents, precocious events of pubertal development were in line with the worldwide secular trend of earlier sexual maturation. HD was only associated with PT and PP in girls. Continuous follow-up of this cohort is a unique opportunity to prospectively address and analyze the interrelationships among HD, early growth, and adiposity as determinants of gonadarche, pubertal rate/sequence progression, and ovarian function.

Ovarian Hormones Organize the Maturation of Inhibitory Neurotransmission in the Frontal Cortex at Puberty Onset in Female Mice

The frontal cortex matures late in development, showing dramatic changes after puberty onset, yet few experiments have directly tested the role of pubertal hormones in cortical maturation. One mechanism thought to play a primary role in regulating the maturation of the neocortex is an increase in inhibitory neurotransmission, which alters the balance of excitation and inhibition. We hypothesized that pubertal hormones could regulate maturation of the frontal cortex by this mechanism. Here, we report that manipulations of gonadal hormones do significantly alter the maturation of inhibitory neurotransmission in the cingulate region of the mouse medial frontal cortex, an associative region that matures during the pubertal transition and is implicated in decision making, learning, and psychopathology. We find that inhibitory neurotransmission, but not excitatory neurotransmission, increases onto cingulate pyramidal neurons during peri-pubertal development and that this increase can be blocked by pre-pubertal, but not post-pubertal, gonadectomy. We next used pre-pubertal hormone treatment to model early puberty onset, a phenomenon increasingly observed in girls living in developed nations. We find that pre-pubertal hormone treatment drives an early increase in inhibitory neurotransmission in the frontal cortex, but not the somatosensory cortex, suggesting that earlier puberty can advance cortical maturation in a regionally specific manner. Pre-pubertal hormone treatment also accelerates maturation of tonic inhibition and performance in a frontal-cortex-dependent reversal-learning task. These data provide rare evidence of enduring, organizational effects of ovarian hormones at puberty and provide a potential mechanism by which gonadal hormones could regulate the maturation of the associative neocortex.

Pubertal development in girls by breast cancer family history: the LEGACY girls cohort

Background

Pubertal milestones, such as onset of breast development and menstruation, play an important role in breast cancer etiology. It is unclear if these milestones are different in girls with a first- or second-degree breast cancer family history (BCFH).

Methods

In the LEGACY Girls Study (n = 1040), we examined whether three mother/guardian-reported pubertal milestones (having reached Tanner Stage 2 or higher (T2+) for breast and pubic hair development, and having started menstruation) differed by BCFH. We also examined whether associations between body size and race/ethnicity and pubertal milestones were modified by BCFH. We used mother/guardian reports as the primary measure of pubertal milestones, but also conducted sensitivity analyses using clinical Tanner measurements available for a subcohort (n = 204). We analyzed cross-sectional baseline data with logistic regression models for the entire cohort, and longitudinal data with Weibull survival models for the subcohort of girls that were aged 5–7 years at baseline (n = 258).

Results

BCFH was modestly, but not statistically significantly, associated with Breast T2+ (odds ratio (OR) = 1.36, 95% confidence interval (CI) = 0.88–2.10), with a stronger association seen in the subcohort of girls with clinical breast Tanner staging (OR = 2.20, 95% CI = 0.91–5.32). In a longitudinal analysis of girls who were aged 5–7 years at baseline, BCFH was associated with a 50% increased rate of having early breast development (hazard ratio (HR) = 1.49, 95% CI = 1.0–2.21). This association increased to twofold in girls who were not overweight at baseline (HR = 2.04, 95% CI = 1.29–3.21). BCFH was not associated with pubic hair development and post-menarche status. The median interval between onset of breast development and menarche was longer for BCFH+ than BCFH– girls (2.3 versus 1.7 years), suggesting a slower developmental tempo for BCFH+ girls. Associations between pubertal milestones and body size and race/ethnicity were similar in girls with or without a BCFH. For example, weight was positively associated with Breast T2+ in both girls with (OR = 1.06 per 1 kg, 95% CI = 1.03–1.10) and without (OR = 1.14 per 1 kg, 95% CI = 1.04–1.24) a BCFH.

Conclusions

These results suggest that BCFH may be related to earlier breast development and slower pubertal tempo independent of body size and race/ethnicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0849-y) contains supplementary material, which is available to authorized users.

Timing of menarche in Norwegian girls: associations with body mass index, waist circumference and skinfold thickness

Background

Research studies show conflicting results regarding the association between menarche and body weight. The purpose of the present study was to investigate if anthropometric indicators of body composition, body mass index (BMI), waist circumference (WC), triceps (TSF) and subscapular skinfold (SSF) thicknesses, were differentially associated with age at menarche in Norwegian girls.

Methods

The association between menarche and BMI, WC, TSF and SSF was investigated in 1481 girls aged 8–15.5 years, and in a subgroup of 181 girls with menarche during the 12 months prior to examination. Anthropometric measures were categorized as low (< −1SDS), average (−1 ≤ SDS ≤ +1) or high (> 1SDS), and menarche according to this classification was analysed with Kaplan-Meier curves and unadjusted and adjusted Cox regression.

Results

The median age at menarche in the total sample was 13.1 years. In the unadjusted models, low categories of all traits were associated with later menarche, and high categories with earlier menarche. When adjusted for other covariates, earlier menarche was only related with a high BMI (Hazard Ratio 1.41, 95% confidence interval (CI) 1.07, 1.85), and later menarche with a low BMI (HR 0.53, 95%CI 0.38, 0.75) and low SSF (HR 0.54, 95%CI 0.39, 0.75). In girls with recent menarche, early menarche was significantly associated with a high BMI in the final model (HR 1.79, 95%CI 1.23, 2.62).

Conclusions

The timing of menarche was associated with the BMI, WC, TSF and SSF, but more strongly so with the BMI. These associations may be related to a common tempo of growth, as the mean age at menarche has remained stable during the last decades during a time period while the prevalence of overweight and obesity has increased significantly.

The follicle-stimulating hormone (FSH) and luteinizing hormone (LH) response to a gonadotropin-releasing hormone analogue test in healthy prepubertal girls aged 10 months to 6 years

OBJECTIVE

Premature thelarche and precocious puberty are frequently diagnosed in girls even below 6 years of age and may be difficult to differentiate in the early stages. A GnRH test is often included in the diagnostic work-up, although interpretation of the GnRH test in girls below 6 years of age is challenging, as no reference interval exists for this age group. The objective is to determine the normal FSH and LH response to a GnRH test in healthy prepubertal girls below 6 years of age.

DESIGN AND METHODS

A standardized GnRH test, baseline reproductive hormones, clinical evaluation and bone age were determined in all participants. Forty-eight healthy normal-weight girls aged 3.5 ± 0.2 years (range: 0.8-5.9 years) were included. Serum concentrations of LH and FSH were measured before and 30 min after the gonadorelin injection.

RESULTS

The 30-min LH responses (mean ± 2 s.d.) were 5.2 ± 4.0 and 2.9 ± 2.5 IU/L and the FSH responses were 23.3 ± 16.2 and 14.5 ± 10.3 IU/L in girls aged 0.8-3.0 years and 3.0-5.9 years respectively. This corresponds to upper cut-off limits for LH of 9.2 IU/L (<3 years) and 5.3 IU/L (3-6 years). The stimulated LH/FSH ratio was 0.23 ± 0.19 (range 0.06-0.43) and did not correlate with age.

CONCLUSIONS

We found that LH increases up to 9.2 IU/L during GnRH test in healthy normal-weight girls below 3 years of age and that the stimulated LH/FSH ratio did not exceed 0.43. Our findings have important implications for appropriate diagnosis of central precocious puberty in girls below 6 years of age.

Endocrine disruption by dietary phyto-oestrogens: impact on dimorphic sexual systems and behaviours

A wide range of health benefits have been ascribed to soya intake including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms. Because it is a hormonally active diet, however, soya can also be endocrine disrupting, suggesting that intake has the potential to cause adverse health effects in certain circumstances, particularly when exposure occurs during development. Consequently, the question of whether or not soya phyto-oestrogens are beneficial or harmful to human health is neither straightforward nor universally applicable to all groups. Possible benefits and risks depend on age, health status, and even the presence or absence of specific gut microflora. As global consumption increases, greater awareness and consideration of the endocrine-disrupting properties of soya by nutrition specialists and other health practitioners is needed. Consumption by infants and small children is of particular concern because their hormone-sensitive organs, including the brain and reproductive system, are still undergoing sexual differentiation and maturation. Thus, their susceptibility to the endocrine-disrupting activities of soya phyto-oestrogens may be especially high. As oestrogen receptor partial agonists with molecular and cellular properties similar to anthropogenic endocrine disruptors such as bisphenol A, the soya phyto-oestrogens provide an interesting model for how attitudes about what is 'synthetic' v. what is 'natural,' shapes understanding and perception of what it means for a compound to be endocrine disrupting and/or potentially harmful. This review describes the endocrine-disrupting properties of soya phyto-oestrogens with a focus on neuroendocrine development and behaviour.

Dairy intake in relation to breast and pubertal development in Chilean girls

Background: Frequent dairy consumption in childhood has been related to higher growth-hormone concentrations that may affect mammary gland and pubertal development.Objective: We evaluated the relation of dairy intake to breast composition at Tanner stage 4 and age at menarche.Design: A total of 515 Chilean girls are included in the Growth and Obesity Cohort Study. The subjects have been followed longitudinally since they were 3-4 y old (from 2006 to the present). Starting in 2013, diet was assessed every 6 mo via a 24-h recall. The breast fibroglandular volume (FGV) was measured with the use of dual-energy X-ray absorptiometry at Tanner stage 4. The date of menarche was reported every 6 mo. Our analysis included 290 girls with data on prospective diet and breast composition and 324 girls with data on prospective diet and age at menarche.Results: The mean ± SD breast FGV and percentage of fibroglandular volume (%FGV) (i.e., FGV divided by total breast volume times 100) at Tanner stage 4 was 81.7 ± 32.2 cm³ and 42.0% ± 16.7%, respectively. Only sweetened, artificially flavored milk-based drinks were associated with the %FGV with girls who consumed >125 g/d having a %FGV that was 4.5% (95% CI: 0.9%, 8.1%) higher than that of girls who consumed none (P-trend = 0.007). Yogurt intake was associated with a lower FGV. Specifically, girls who consumed >125 g yogurt/d had -10.2 cm³ (95% CI: -20.2, -0.3 cm³) less FGV than did girls who consumed no yogurt (P-trend = 0.03). The majority (90.7%) of girls in our cohort attained menarche before the data analyses with a mean ± SD age at menarche of 11.9 ± 0.7 y. In multivariable models, low-fat dairy, low-fat milk, and yogurt intakes were associated with a later age at menarche. In particular, girls who consumed >125 g yogurt/d had menarche, on average, 4.6 mo (95% CI: 1.9, 7.4 mo) later than girls who consumed no yogurt (P-trend = 0.01).Conclusion: More-frequent consumption of sweetened, artificially-flavored milk-based drinks is associated with a higher %FGV, whereas higher yogurt intake is associated with a lower FGV and delayed age at menarche in Chilean girls.

Associations between levels of insulin-like growth factor 1 and sinusoidal obstruction syndrome after allogeneic haematopoietic stem cell transplantation

Allogeneic myeloablative haematopoietic stem cell transplantation (HSCT) is challenged by severe adverse events, as cytotoxic effects of the conditioning may result in systemic inflammation, leaky epithelial barriers and organ toxicities, contributing to treatment-related morbidity and mortality. We hypothesised that insulin-like growth factor-1 (IGF-1), a mediator of growth and proliferation of various tissues, may attenuate chemotherapy-induced tissue damage after HSCT. We prospectively measured plasma levels of IGF-1 and its binding protein 3 (IGFBP-3) in 41 patients undergoing myeloablative HSCT. IGF-1 and IGFBP-3 levels were inversely correlated with C-reactive protein and interleukin-6 levels post HSCT. In multivariate analyses, low levels of IGF-1 and IGFBP-3 before conditioning were associated with increased risk of developing sinusoidal obstruction syndrome (SOS; OR=5.00 per 1 SDS decrease in IGF-1 (95% CI: 1.45-16.67), P=0.011 and OR=5.00 (1.37-20.00), P=0.015, respectively). Furthermore, low pre-transplant levels of IGF-1 and IGFBP-3 were associated with increased fluid retention during the first 21 days post transplant (OR=7.69 (95% CI: 1.59-33.33), P=0.012, and OR=2.94 (1.03-8.33), P=0.045). These data suggest that high levels of IGF-1 and IGFBP-3 may have a protective effect against fluid retention and SOS, possibly by attenuating systemic inflammation, and may prove useful as predictive biomarkers of SOS.

Larval crowding accelerates C. elegans development and reduces lifespan

Environmental conditions experienced during animal development are thought to have sustained impact on maturation and adult lifespan. Here we show that in the model organism C. elegans developmental rate and adult lifespan depend on larval population density, and that this effect is mediated by excreted small molecules. By using the time point of first egg laying as a marker for full maturity, we found that wildtype hermaphrodites raised under high density conditions developed significantly faster than animals raised in isolation. Population density-dependent acceleration of development (Pdda) was dramatically enhanced in fatty acid β-oxidation mutants that are defective in the biosynthesis of ascarosides, small-molecule signals that induce developmental diapause. In contrast, Pdda is abolished by synthetic ascarosides and steroidal ligands of the nuclear hormone receptor DAF-12. We show that neither ascarosides nor any known steroid hormones are required for Pdda and that another chemical signal mediates this phenotype, in part via the nuclear hormone receptor NHR-8. Our results demonstrate that C. elegans development is regulated by a push-pull mechanism, based on two antagonistic chemical signals: chemosensation of ascarosides slows down development, whereas population-density dependent accumulation of a different chemical signal accelerates development. We further show that the effects of high larval population density persist through adulthood, as C. elegans larvae raised at high densities exhibit significantly reduced adult lifespan and respond differently to exogenous chemical signals compared to larvae raised at low densities, independent of density during adulthood. Our results demonstrate how inter-organismal signaling during development regulates reproductive maturation and longevity.

The nematode C. elegans is one of the most highly developed models for the elucidation of conserved mechanisms connecting environmental cues to the regulation of animal lifespan and development. Surprisingly, the effects of larval population density on developmental timing and adult lifespan have not been investigated, although population density is known to affect developmental dynamics and survival in many species. We here describe a novel phenotype in C. elegans: population density-dependent acceleration of development. That high population density would accelerate development is unexpected, since at high population density accumulation of dauer pheromone, a developmental arrest signal, would be expected to slow down development. However, we found that C. elegans development is regulated by a pull-push mechanism, based on at least two different types of pheromone-like signals: the developmental acceleration signal we first describe in this manuscript, and its antagonist, the dauer pheromone, whose chemical make-up has gradually emerged over the past 10 years. We further show that both developmental acceleration and deceleration are mediated by two nuclear hormone receptors that have close mammalian homologs. Finally we demonstrate that larval population density predetermines adult lifespan in C. elegans hermaphrodites, including responses to hormonal stimuli during adulthood.

Gynecologic and Obstetric Consequences of Obesity in Adolescent Girls

In the past few decades, there has been an overwhelming increase in childhood and adolescent obesity worldwide. Besides the well recognized cardiometabolic complications and other physical conditions associated with obesity, during adolescence, it causes psychological and social distress in a period of life that is already sensitive for a girl. This in turn increases their risk of low self-esteem and depression. Furthermore, obesity diminishes health-related quality of life and years of life. Overweight and obese teenagers are more likely to have gynecologic and obstetric complications, during adolescence and also later in life. Consequences of obese and overweight childhood and adolescence include sexual maturation and reproductive dysfunction, alterations in menstruation, dysmenorrhea, risky sexual behavior, and inefficient use of contraception, polycystic ovary syndrome, bone density abnormalities, macromastia, and an increased risk of breast and endometrial cancer. Obese adolescents are at greater risk of pregnancy and perinatal complications, such as preeclampsia, gestational hypertension and preeclampsia, gestational diabetes mellitus, primary cesarean delivery, and induction of labor, to mention a few. Evidence shows that infants born to obese teenagers are also more likely to have complications including preterm or post-term delivery, small-for-gestational age newborns, macrosomia, meconium aspiration, respiratory distress, and even stillbirth, among others. This comprehensive review focuses on the gynecological and obstetric consequences of obesity in adolescent girls.

Isotope-dilution TurboFlow-LC-MS/MS method for simultaneous quantification of ten steroid metabolites in serum

An isotope-dilution TurboFlow-LC-MS/MS method for simultaneous quantification of the ten steroid metabolites dehydroepiandrosterone sulfate (DHEAS), progesterone, 17α-hydroxyprogesterone (17-OHP), Δ4-androstenedione (Adione), corticosterone, 11-deoxycortisol, cortisol, cortisone, testosterone (T), and estrone 3-sulfate (E1-S) in serum was developed and validated. Limits of quantification, variability (inter- and intra-day), analytical range and linearity were all found to be acceptable for clinical use. Furthermore, sample stability was evaluated including the influence of freeze-thaw cycles and the effects of temperature and storage time. The method was applied to 391 serum samples from healthy, Danish boys 10-18years old. The concentration ranges of the included steroid metabolites for this population are presented. Concentrations of DHEAS, 17-OHP, Adione and T in the 391 serum samples were furthermore compared to results obtained using an existing LC-MS/MS method in our laboratory. Excellent agreement was found between the methods. Furthermore, the improved sensitivity of the new method allowed for quantification of a number of samples found to be below the LOQs of the existing method. Thus, the two instruments and their associated methods were validated as possible back-ups for each other, which we consider an extremely important issue in high-throughput laboratories analyzing clinical samples on a regular basis. The ten analytes included can be analyzed simultaneously but it is also possible only to include some of these analytes for specific diagnostic purposes which make the new method an extremely useful tool in the clinical laboratory.

Prenatal exposure to vitamin D from fortified margarine and risk of fractures in late childhood: period and cohort results from 222 000 subjects in the D-tect observational study

Prenatal low vitamin D may have consequences for bone health. By means of a nationwide mandatory vitamin D fortification programme, we examined the risk of fractures among 10-18-year-old children from proximate birth cohorts born around the date of the termination of the programme. For all subjects born in Denmark during 1983-1988, civil registration numbers were linked to the Danish National Patient Registry for incident and recurrent fractures occurring at ages 10-18 years. Multiplicative Poisson models were used to examine the association between birth cohort and fracture rates. The variation in fracture rates across birth cohorts was analysed by fitting an age-cohort model to the data. We addressed the potential modification of the effect of vitamin D availability by season of birth. The risk of fractures was increased among both girls and boys who were born before the vitamin D fortification terminated in 1985 (rate ratio (RR) exposed v. non-exposed girls: 1·15 (95 % CI 1·11, 1·20); RR exposed v. non-exposed boys: 1·11 (95 % CI 1·07, 1·14). However, these associations no longer persisted after including the period effects. There was no interaction between season of birth and vitamin D availability in relation to fracture risk. The study did not provide evidence that prenatal exposure to extra vitamin D from a mandatory fortification programme of 1·25 µg vitamin D/100 g margarine was sufficient to influence the risk of fractures in late childhood, regardless of season of birth. Replication studies are needed.

Pubertal Progression and Reproductive Hormones in Healthy Girls With Transient Thelarche

CONTEXT

Detailed evaluation of pubertal progression in girls from longitudinal studies is sparse, and the phenomenon of transient thelarche (TT), defined as the appearance, regression, and subsequent reappearance of breast buds, in healthy girls remains undescribed.

OBJECTIVE

To describe TT in terms of pubertal progression, growth, genotypes, and reproductive hormones and to apply new puberty nomograms for breast stages, pubic hair, and menarche.

DESIGN

A prospective, longitudinal population-based study.

PATIENTS OR OTHER PARTICIPANTS

Ninety-eight healthy Danish schoolchildren (Caucasian girls) followed longitudinally as part of the COPENHAGEN Puberty Study were included in the evaluation of TT. A total of 1466 girls from 2 cross-sectional studies were included in the creation of the puberty nomograms.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pubertal progression, specifically thelarche, reproductive hormones, genotype, and growth.

RESULTS

Twelve of 98 (12%) girls experienced TT. A larger proportion of girls with TT entered puberty by the pubarche pathway (50%) compared with girls with normal progression (15.4%), P = 0.014. Girls with TT progressed through puberty normally when evaluated using puberty nomograms. Reproductive hormones and growth velocity were lower at the first (transient) thelarche than the second (permanent) thelarche.

CONCLUSION

TT is a frequent phenomenon that appears to be a peripheral occurrence independent of central puberty. It does not appear to affect subsequent pubertal progression as evaluated by our new puberty nomograms.

Brief Report: Maternal Age of Menarche and Adiposity: Evidence from Hong Kong's "Children of 1997" Birth Cohort

BACKGROUND

Earlier age of menarche predicts chronic diseases. Earlier maternal age of menarche is also associated with higher body mass index (BMI) and height into childhood.

METHODS

We used generalized estimating equations in Hong Kong's "Children of 1997" birth cohort to examine the adjusted association of maternal age of menarche with BMI and height z score, and whether associations varied by maternal birthplace.

RESULTS

Earlier maternal age of menarche was not associated with infant BMI but was associated subsequently with higher BMI in childhood and at puberty. Maternal age of menarche was negatively associated with height in children of Hong Kong-born mothers, but positively associated with infant length for children with mothers born in China (P value for interaction 0.02).

CONCLUSION

These different patterns suggest drivers of adiposity and linear growth differ, and are more influential in some circumstances. Understanding these drivers may indicate setting-specific interventions to prevent childhood obesity.

Does puberty mark a transition in sensitive periods for plasticity in the associative neocortex?

Postnatal brain development is studded with sensitive periods during which experience dependent plasticity is enhanced. This enables rapid learning from environmental inputs and reorganization of cortical circuits that matches behavior with environmental contingencies. Significant headway has been achieved in characterizing and understanding sensitive period biology in primary sensory cortices, but relatively little is known about sensitive period biology in associative neocortex. One possible mediator is the onset of puberty, which marks the transition to adolescence, when animals shift their behavior toward gaining independence and exploring their social world. Puberty onset correlates with reduced behavioral plasticity in some domains and enhanced plasticity in others, and therefore may drive the transition from juvenile to adolescent brain function. Pubertal onset is also occurring earlier in developed nations, particularly in unserved populations, and earlier puberty is associated with vulnerability for substance use, depression and anxiety. In the present article we review the evidence that supports a causal role for puberty in developmental changes in the function and neurobiology of the associative neocortex. We also propose a model for how pubertal hormones may regulate sensitive period plasticity in associative neocortex. We conclude that the evidence suggests puberty onset may play a causal role in some aspects of associative neocortical development, but that further research that manipulates puberty and measures gonadal hormones is required. We argue that further work of this kind is urgently needed to determine how earlier puberty may negatively impact human health and learning potential. This article is part of a Special Issue entitled SI: Adolescent plasticity.

Associations of urinary phthalate and phenol biomarkers with menarche in a multiethnic cohort of young girls

To study potential environmental influences on puberty in girls, we investigated urinary biomarkers in relation to age at menarche. Phenols and phthalates were measured at baseline (6-8 years of age). Menarche was ascertained over 11 years for 1051 girls with menarche and biomarkers. Hazards ratios were estimated from Cox models adjusted for race/ethnicity and caregiver education (aHR, 95% confidence intervals [CI] for 5th vs 1st quintile urinary biomarker concentrations). 2,5-Dichlorophenol was associated with earlier menarche (aHR 1.34 [1.06-1.71]); enterolactone was associated with later menarche (aHR 0.82 [0.66-1.03]), as was mono-3-carboxypropyl phthalate (MCPP) (aHR 0.73 [0.59-0.91]); the three p-trends were <0.05. Menarche differed by 4-7 months across this range. Enterolactone and MCPP associations were stronger in girls with below-median body mass index. These analytes were also associated with age at breast development in this cohort. Findings from this prospective study suggest that some childhood exposures are associated with pubertal timing.

Precocious Puberty or Premature Thelarche: Analysis of a Large Patient Series in a Single Tertiary Center with Special Emphasis on 6- to 8-Year-Old Girls

INTRODUCTION

We describe the etiology, MRI findings, and growth patterns in girls who had presented with signs of precocious puberty (PP), i.e., premature breast development or early menarche. Special attention was paid to the diagnostic findings in 6- to 8-year-olds.

MATERIALS AND METHODS

We reviewed the medical records of 149 girls (aged 0.7-10.3 years) who had been evaluated for PP in the Helsinki University Hospital between 2001 and 2014.

RESULTS

In 6- to 8-year-old girls, PP was most frequently caused by idiopathic gonadotropin-releasing hormone (GnRH)-dependent PP (60%) and premature thelarche (PT; 39%). The former subgroup grew faster (8.7 ± 2.0 cm/year, n = 58) than the girls with PT (7.0 ± 1.1 cm/year, n = 32) (P < 0.001), and the best discrimination for GnRH-dependent PP was achieved with a growth velocity cut-off value of 7.0 cm/year (sensitivity 92% and specificity 58%) [area under the curve 0.82, 95% confidence interval (CI) 0.73-0.91, P < 0.001]. Among asymptomatic and previously healthy 6- to 8-year-old girls with GnRH-dependent PP, one (1.7%, 95% CI 0.3-9.7%) had a pathological brain MRI finding requiring surgical intervention (craniopharyngioma). In girls younger than 3 years, the most frequent cause of breast development was PT, and, in 3- to 6-year-olds, GnRH-dependent PP.

CONCLUSION

In 6- to 8-year-old girls, analysis of growth velocity is helpful in differentiating between PT and GnRH-dependent PP. Although the frequency of clinically relevant intracranial findings in previously healthy, asymptomatic 6- to 8-year-old girls was low, they can present without any signs or symptoms, which favors routine MRI imaging also in this age group.

The Evolution of the Age at Menarche from Prehistorical to Modern Times

Menarche denotes the onset of the female reproductive capacity. The age that menarche occurs is mostly attributed to the interaction of genetics and various environmental factors. Herein, the author describes the evolution of the age at menarche from prehistoric to the present times. Data from skeletal remains suggest that in the Paleolithic woman menarche occurred at an age between 7 and 13 years, early sexual maturation being a trade-off for reduced life expectancy. In the classical, as well as in the medieval years, the age at menarche was generally reported to be at approximately 14 years, with a range from 12 to 15 years. A significant retardation of the age at menarche occurred in the beginning of the modern times, soon after the industrial revolution, due to the deterioration of the living conditions, with most studies reporting menarche to occur at 15-16 years. In the 20th century, especially in the second half of it, in the industrialized countries, the age at menarche decreased significantly, as a result of the improvement of the socioeconomic conditions, occurring at 12-13 years. In the present times, in the developed countries, this trend seems to slow down or level off.

Associations of Peripubertal Serum Dioxin and Polychlorinated Biphenyl Concentrations with Pubertal Timing among Russian Boys

BACKGROUND

Dioxins, furans, and polychlorinated biphenyls (PCBs), dioxin-like and non-dioxin-like, have been linked to alterations in puberty.

OBJECTIVES

We examined the association of peripubertal serum levels of these compounds [and their toxic equivalents (TEQs)] with pubertal onset and maturity among Russian boys enrolled at ages 8-9 years and followed prospectively through ages 17-18 years.

METHODS

At enrollment, 473 boys had serum dioxin-like compounds and PCBs measured. At the baseline visit and annually until age 17-18 years, a physician performed pubertal staging [genitalia (G), pubarche (P), and testicular volume (TV)]. Three hundred fifteen subjects completed the follow-up visit at 17-18 years of age. Pubertal onset was defined as TV > 3 mL, G2, or P2. Sexual maturity was defined as TV ≥ 20 mL, G5, or P5. Multivariable interval-censored models were used to evaluate associations of lipid-standardized concentrations with pubertal timing.

RESULTS

Medians (interquartile ranges) of the sum of dioxin-like compounds, TEQs, and non-dioxin-like PCBs were 362 pg/g lipid (279-495), 21.1 pg TEQ/g lipid (14.4-33.2), and 250 ng/g lipid (164-395), respectively. In adjusted models, the highest compared to lowest TEQ quartile was associated with later pubertal onset [TV = 11.6 months (95% CI: 3.8, 19.4); G2 = 10.1 months (95% CI: 1.4, 18.8)] and sexual maturity [TV = 11.6 months (95% CI: 5.7, 17.6); G5 = 9.7 months (95% CI: 3.1, 16.2)]. However, the highest compared to the lowest quartile of non-dioxin-like PCBs, when co-adjusted by TEQs, was associated with earlier pubertal onset [TV = -8.3 months (95% CI:-16.2, -0.3)] and sexual maturity [TV = -6.3 months (95% CI:-12.2, -0.3); G5 = -7.2 months (95% CI:-13.8, -0.6)]; the non-dioxin-like PCB associations were only significant when adjusted for TEQs. TEQs and PCBs were not significantly associated with pubic hair development.

CONCLUSIONS

Our results suggest that TEQs may delay, while non-dioxin-like PCBs advance, the timing of male puberty. Citation: Burns JS, Lee MM, Williams PL, Korrick SA, Sergeyev O, Lam T, Revich B, Hauser R. 2016. Associations of peripubertal serum dioxin and polychlorinated biphenyl concentrations with pubertal timing among Russian boys. Environ Health Perspect 124:1801-1807; http://dx.doi.org/10.1289/EHP154.

Estimation of the dietary requirement for vitamin D in white children aged 4-8 y: a randomized, controlled, dose-response trial

BACKGROUND

Children in northern latitudes are at high risk of vitamin D deficiency during winter because of negligible dermal vitamin D₃ production. However, to our knowledge, the dietary requirement for maintaining the nutritional adequacy of vitamin D in young children has not been investigated.

OBJECTIVE

We aimed to establish the distribution of vitamin D intakes required to maintain winter serum 25-hydroxyvitamin D [25(OH)D] concentrations above the proposed cutoffs (25, 30, 40, and 50 nmol/L) in white Danish children aged 4-8 y living at 55°N.

DESIGN

In a double-blind, randomized, controlled trial 119 children (mean age: 6.7 y) were assigned to 0 (placebo), 10, or 20 μg vitamin D₃/d supplementation for 20 wk. We measured anthropometry, dietary vitamin D, and serum 25(OH)D with liquid chromatography-tandem mass spectrometry at baseline and endpoint.

RESULTS

The mean ± SD baseline serum 25(OH)D was 56.7 ± 12.3 nmol/L (range: 28.7-101.4 nmol/L). Serum 25(OH)D increased by a mean ± SE of 4.9 ± 1.3 and 17.7 ± 1.8 nmol/L in the groups receiving 10 and 20 μg vitamin D₃/d, respectively, and decreased by 24.1 ± 1.2 nmol/L in the placebo group (P < 0.001). A nonlinear model of serum 25(OH)D as a function of total vitamin D intake (diet and supplements) was fit to the data. The estimated vitamin D intakes required to maintain winter serum 25(OH)D >30 (avoiding deficiency) and >50 nmol/L (ensuring adequacy) in 97.5% of participants were 8.3 and 19.5 μg/d, respectively, and 4.4 μg/d was required to maintain serum 25(OH)D >40 nmol/L in 50% of participants.

CONCLUSIONS

Vitamin D intakes between 8 and 20 μg/d are required by white 4- to 8-y-olds during winter in northern latitudes to maintain serum 25(OH)D >30-50 nmol/L depending on chosen serum 25(OH)D threshold. This trial was registered at clinicaltrials.gov as NCT02145195.

What is the most accurate and reliable methodological approach for predicting peak height velocity in adolescents? A systematic review

OBJECTIVES

To identify the most accurate method of predicting peak height velocity in adolescents.

DESIGN

Systematic review.

METHODS

A comprehensive literature search of six electronic databases and reference lists was conducted. Studies that met selection criteria of (1) observational longitudinal cohort study (2) reproducible method/s of predicting peak height velocity (3) minimum six-month follow-up (4) healthy male and/or female adolescent subjects, with the exception of participants with adolescent idiopathic scoliosis, were considered for review. Studies were screened using a modified quality assessment checklist, with only those scoring >50% included. The type of surrogate measure of peak height velocity, its reliability and ability to predict peak height velocity were extracted from the year or stage immediately preceding peak height velocity. We defined "predict" as when both the estimates of effect and 95% confidence intervals of the surrogate occurred prior to the actual age of PHV.

RESULTS

The nine included studies examined three anthropometric, three equation and four radiographic-based surrogates for PHV. Of these, the radiographic measures were reported to exhibit moderate to high intra- and inter-rater reliability. Three of the four radiographic surrogates predicted PHV. Two anthropometric measures also predicted PHV but reliability of the measures is unknown. All equation-based methods predicted the timing of PHV to occur later than it actually happened when applied in the year prior to expected PHV.

CONCLUSIONS

In the year/stage immediately preceding peak height velocity, radiograph-based methods appear to be accurate and reliable surrogates.

Could tea polyphenols be beneficial for preventing the precocious puberty?

Precocious puberty which impacts children physically and psychologically has become one of the health problem over the world. However, the mechanism and preventive measures of precocious puberty is still not clear. Recent studies suggested that leptin may act as the 'permissive factor' to initiate the puberty by regulating gonadotrophin-releasing hormone secretion. Previous evidence from animal and human studies found that tea polyphenols can reduce serum leptin levels in vivo and inhibit the expression of leptin in adipose tissue. This article focus on whether tea polyphenols could delay the onset of puberty by reducing leptin levels. To verify the possibility of tea polyphenols on preventing precocious puberty, animal experiment can be used. Our hypothesis that tea polyphenols could prevent the precocious puberty may provide important potential way for the prevention and control of children precocious puberty.

Nonparametric estimation of time-to-event distribution based on recall data in observational studies

In a cross-sectional observational study, time-to-event distribution can be estimated from data on current status or from recalled data on the time of occurrence. In either case, one can treat the data as having been interval censored, and use the nonparametric maximum likelihood estimator proposed by Turnbull (J R Stat Soc Ser B 38:290-295, 1976). However, the chance of recall may depend on the time span between the occurrence of the event and the time of interview. In such a case, the underlying censoring would be informative, rendering the Turnbull estimator inappropriate. In this article, we provide a nonparametric maximum likelihood estimator of the distribution of interest, by using a model adapted to the special nature of the data at hand. We also provide a computationally simple approximation of this estimator, and establish the consistency of both the original and the approximate versions, under mild conditions. Monte Carlo simulations indicate that the proposed estimators have smaller bias than the Turnbull estimator based on incomplete recall data, smaller variance than the Turnbull estimator based on current status data, and smaller mean squared error than both of them. The method is applied to menarcheal data from a recent Anthropometric study of adolescent and young adult females in Kolkata, India.

Glandular breast tissue volume by magnetic resonance imaging in 100 healthy peripubertal girls: evaluation of clinical Tanner staging

BACKGROUND

Appearance of glandular breast tissue may be difficult to distinguish from fat tissue by palpation, especially in obese girls. To our knowledge, validation of the clinical assessment of pubertal breast stages by magnetic resonance imaging (MRI) has never been performed. Our objective was to report normative data of glandular breast tissue volume and validate the clinical evaluation of pubertal breast staging by MRI of breast tissue and to evaluate circulating reproductive hormone levels and estrogen-dependent transabdominal ultrasound (TAUS) parameters as markers of glandular breast tissue.

METHODS

Glandular breast tissue volume quantified by MRI and breast stage evaluation was performed in 100 healthy peripubertal girls. Circulating levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin B, and estradiol were measured by immunoassays. Ovarian volume, uterine volume, and endometrial thickness were assessed by TAUS.

RESULTS

Glandular breast tissue volume was positively associated with Tanner stages (r = 0.858, P < 0.001). The sensitivity and specificity of breast palpation to detect presence of glandular breast tissue using MRI as gold standard were 96 and 95%, respectively. The best parameters to distinguish prepubertal girls from girls with breast development were: LH (area under the curve (AUC) by receiver operating characteristic analysis = 0.871), inhibin B (AUC = 0.847) and estradiol (AUC = 0.830).

CONCLUSION

Clinical palpation reliably detects the presence of glandular breast tissue.

The investigation of children and adolescents with abnormalities of pubertal timing

Concerns with pubertal development are common and can cause considerable distress to patients and their carers. Many presentations reflect normal variations of pubertal timing and primarily require reassurance, although patients may opt for interventions. Other presentations need active management to avoid significant adverse effects on growth and psychosocial development. All should undergo careful assessment, particularly as some children or adolescents presenting with abnormalities in pubertal timing may have serious pathology which requires urgent investigations and treatment. This review describes the appropriate investigations and their interpretation for young people presenting with disorders in pubertal timing.

In utero exposure to organochlorine pesticides and early menarche in the Avon Longitudinal Study of Parents and Children

INTRODUCTION

Epidemiologic data supporting the role of organochlorine pesticides in pubertal development are limited.

METHODS

Using a nested case-control design, serum collected during pregnancy from mothers of 218 girls who reported menarche before 11.5years of age (cases) and 230 girls who reported menarche at or after 11.5years of age (controls) was analyzed for 9 organochlorines and metabolites. We analyzed the association between in utero organochlorine concentrations and early menarche using multivariate logistic regression controlling for mother's age at menarche, or mother's prenatal BMI.

RESULTS

We did not observe an association between in utero exposure to HCB, β-HCH, ϒ-HCH, p,p'-DDT, p,p'-DDE, oxychlordane or trans-nonachlor and early menarche.

CONCLUSIONS

This study is the first to examine the association between in utero exposure to HCB, β-HCH, ϒ-HCH, oxychlordane or trans-nonachlor and early menarche. In utero exposure to organochlorine pesticides does not appear to have a role in the timing of menarche in this study.

Vitamin D status of Icelandic children and its influence on bone accrual

The importance of vitamin D for children's bone health has been well established, but the effects of less severe deficiency are not fully known. The main objective of this study was to assess the vitamin D status of Icelandic children at the age of 7, and again at 9 years of age, and the association of vitamin D status with bone mineral content and bone accrual over 2 years. We invited 321 children to participate in this study, and 267 (83 %) took part; 211 (79 %) underwent a DXA scan and 164 were again scanned 2 years later; 159 (60 %) vitamin D samples were measured and 119 (75 %) were measured again 2 years later. At age 7, 65 % of the children had vitamin D concentrations <50 nmol/l, and at age 9 this figure was 60 %. At age 7, 43 % of the children had insufficient amounts of vitamin D (37.5-50 nmol/l), and 22 % had a vitamin D deficiency (<37.5 nmol/l). In linear regression analysis, no association was found between vitamin D and bone mineral content. Furthermore, there was no significant difference in bone accrual over 2 years for the children with insufficient or deficient vitamin D at both ages, compared to those having more than 50 nmol/l at both time points. More than 60 % of Icelandic children have inadequate concentrations of vitamin D in serum repeatedly over a 2-year interval. However, vitamin D in the range did not have a significant effect on bone mineral content or accrual at ages 7 and 9.

Consumer Neoteny

This research explores childlike consumer behavior from an evolutionary perspective. More specifically, it uses the concept of neoteny to show that the retention of ancestors’ juvenile characteristics is related to specific behaviors. The results of factor analyses conducted on a UK sample ( n = 499) and a French sample ( n = 292) 7 years later indicate four dimensions of childlike consumer behavior, namely, stimulus seeking, reality conflict, escapism, and control of aggression.

The evaluation of possible role of endocrine disruptors in central and peripheral precocious puberty

Exposure to environmental chemicals can affect genetic and epigenetic molecular pathways and may cause altered growth and development. Among those exposures, endocrine-disrupting chemicals (EDCs) are of particular concern as humans are abundantly exposed to these chemicals by various means in every period of life. Several well-known environmental chemicals, including phthalates and bisphenol A (BPA), are classified as EDCs. These EDCs are suggested to play roles in early onset of puberty in girls. The aim of this study is to determine plasma phthalate (di(2-ethylhexyl)phthalate [DEHP] and its main metabolite mono(2-ethylhexyl)phthalate [MEHP]) and urinary BPA levels in girls with idiopathic central precocious puberty (CPP) and peripheral precocious puberty (PPP). This study was performed on newly diagnosed idiopathic central precocious puberty (CPP) patients (n = 42) and peripheral precocious puberty (PPP) (n = 42) patients, who were admitted to Keçiören Training and Research Hospital, Clinic of Pediatric Endocrinology between August 2012 and -July 2013. Nonobese healthy girls (n = 50) were used as the control group. Urinary BPA levels were not statistically different in control, PPP and CPP groups (medians 10.91, 10.63 and 10.15 μg/g creatinine, respectively; p > 0.05). Plasma DEHP levels were significantly higher in PPP group when compared to control. Plasma MEHP levels were not significantly different in control and PPP groups (p > 0.05). However, in CPP group, both plasma DEHP and MEHP levels were significantly higher than control and PPP groups. This study showed that phthalates might play a role in the occurence of CPP in girls.

Metabolic control of female puberty: potential therapeutic targets

INTRODUCTION

The onset of puberty in females is highly sensitive to the nutritional status and the amount of energy reserves of the organism. This metabolic information is sensed and transmitted to hypothalamic GnRH neurons, considered to be ultimately responsible for triggering puberty through the coordinated action of different peripheral hormones, central neurotransmitters, and molecular mediators.

AREAS COVERED

This article will review and discuss (i) the relevant actions of the adipose hormone leptin, as a stimulatory/permissive signal, and the gut hormone ghrelin, as an inhibitory factor, in the metabolic control of female puberty; (ii) the crucial role of the hypothalamic kisspeptin neurons, recently emerged as essential gatekeepers of puberty, in transmitting this metabolic information to GnRH neurons; and (iii) the potential involvement of key cellular energy sensors, such as mTOR, as molecular mediators in this setting.

EXPERT OPINION

The thorough characterization of the physiological roles of the above elements in the metabolic control of female puberty, along with the discovery of novel factors, pathways, and mechanisms involved, will promote our understanding of the complex networks connecting metabolism and puberty and, ultimately, will aid in the design of target-specific treatments for female pubertal disorders linked to conditions of metabolic stress.

Infection and pubertal timing: a systematic review

The decline in age of pubertal timing has serious public health implications ranging from psychosocial adjustment problems to a possible increase in reproductive cancers. One biologically plausible explanation for the decline is a decrease in exposures to infections. To systematically review studies that assess the role of infection in pubertal timing, Medline, Web of Science and EMBASE were systematically searched and retrieved studies were reviewed for eligibility. Eligible studies examined the association between infections, including microbial exposures, and physical pubertal characteristics (breast, genitalia and pubic hair development) or age at menarche. We excluded studies that were published in a language other than English, focused on precocious puberty, were case studies, and/or included youth with autoimmune diseases. We report on study design, population characteristics, measurement of infection and puberty and the main effects of infection on pubertal development. Based on our search terms we identified 1372 unique articles, of which only 15 human and five animal studies met our eligibility criteria. Not all studies examined all outcomes. Infection was associated with later breast development (4/4 human studies), with less consistent evidence for genitalia and pubic hair development. Seven studies assessed age at menarche with inconsistent findings (three supporting later, four no association). We conclude that a small but consistent literature supports that infection is associated with later breast development; the evidence for other pubertal events and age at menarche is less clear. Where fewer childhood infections coincide with the rise in incidence of hormone-related cancers.

Comparison of Clinical, Maternal, and Self Pubertal Assessments: Implications for Health Studies

BACKGROUND

Most epidemiologic studies of puberty have only 1 source of pubertal development information (maternal, self or clinical). Interpretation of results across studies requires data on reliability and validity across sources.

METHODS

The LEGACY Girls Study, a 5-site prospective study of girls aged 6 to 13 years (n = 1040) collected information on breast and pubic hair development from mothers (for all daughters) and daughters (if ≥10 years) according to Tanner stage (T1-5) drawings. At 2 LEGACY sites, girls (n = 282) were also examined in the clinic by trained professionals. We assessed agreement (κ) and validity (sensitivity and specificity) with the clinical assessment (gold standard) for both the mothers' and daughters' assessment in the subcohort of 282. In the entire cohort, we examined the agreement between mothers and daughters.

RESULTS

Compared with clinical assessment, sensitivity of maternal assessment for breast development was 77.2 and specificity was 94.3. In girls aged ≥11 years, self-assessment had higher sensitivity and specificity than maternal report. Specificity for both mothers and self, but not sensitivity, was significantly lower for overweight girls. In the overall cohort, maternal and daughter agreement for breast development and pubic hair development (T2+ vs T1) were similar (0.66, [95% confidence interval 0.58-0.75] and 0.69 [95% confidence interval 0.61-0.77], respectively), but declined with age. Mothers were more likely to report a lower Tanner stage for both breast and pubic hair compared with self-assessments.

CONCLUSIONS

These differences in validity should be considered in studies measuring pubertal changes longitudinally when they do not have access to clinical assessments.

The Relationship Between Greater Prepubertal Adiposity, Subsequent Age of Maturation, and Bone Strength During Adolescence

This longitudinal study investigated whether greater prepubertal adiposity was associated with subsequent timing of maturation and bone strength during adolescence in 135 girls and 123 boys participating in the Iowa Bone Development Study. Greater adiposity was defined using body mass index (BMI) data at age 8 years to classify participants as overweight (OW, ≥85th percentile for age and sex) or healthy weight (HW). Maturation was defined as the estimated age of peak height velocity (PHV) based on a series of cross-sectional estimates. Measurements were taken at ages 11, 13, 15, and 17 years for estimates of body composition by dual-energy X-ray absorptiometry (DXA), bone compression (bone strength index), and torsion strength (polar strength-strain index) at the radius and tibia by pQCT, and femoral neck bending strength (section modulus) by hip structural analysis. Bone strength in OW versus HW were evaluated by fitting sex-specific linear mixed models that included centered age (visit age - grand mean age of cohort) as the time variable and adjusted for change in fat mass, and limb length in model 1. Analyses were repeated using biological age (visit age - age PHV) as the time variable for model 1 with additional adjustment for lean mass in model 2. BMI was negatively associated with age of maturation (p < 0.05). OW versus HW girls had significantly greater bone strength (p < 0.001) in model 1, whereas OW versus HW boys had significantly greater bone strength (p < 0.001) at the tibia and femoral neck but not radius (p > 0.05). Analyses were repeated using biological age, which yielded reduced parameter estimates for girls but similar results for boys (model 1.) Differences were no longer present after adjustment for lean mass (model 2) in girls (p > 0.05) whereas differences at the tibia were sustained in boys (p < 0.05). These findings demonstrate sex- and site-specific differences in the associations between adiposity, maturation, and bone strength. © 2016 American Society for Bone and Mineral Research.

Pubertal Onset in Boys and Girls Is Influenced by Pubertal Timing of Both Parents

CONTEXT

Epidemiological evidence on maternal and paternal heritability of the wide normal variation within pubertal timing is sparse.

OBJECTIVE

We aimed to estimate the impact of parental pubertal timing on the onset of puberty in boys and girls.

DESIGN

Annual pubertal examinations of healthy children in a longitudinal cohort study. Information on parental timing of puberty (earlier, comparable to, or later compared to peers) and menarche age was retrieved from questionnaires.

PARTICIPANTS

A total of 672 girls and 846 boys.

MAIN OUTCOME MEASURES

Age at onset of pubic hair (PH2+), breasts (B2+), and menarche in girls; and PH2+, genital stage (G2+), and testis >3 mL with orchidometer (Tvol3+) in boys.

RESULTS

In boys, pubertal onset was significantly associated with pubertal timing of both parents. PH2+ and Tvol3+ were earlier: -11.8 months (95% confidence interval, -16.8, -6.8)/-8.9 (-12.8, -4.9), and -9.5 (-13.9, -5.1)/-7.1 (-10.4, -3.7) if the father/mother, respectively, had early pubertal development compared to late. In girls, menarche was significantly associated with both parents' pubertal timing: -10.5 months (-15.9, -5.1)/-10.1 (-14.3, -6.0) if father/mother had early pubertal development compared to late. For the onset of PH2+ and B2+ in girls, estimates were -7.0 months (-12.6, -1.4) and -4.1 (-10.6, +2.4)/-6.7 (-11.0, -2.5), and -6.7 (-11.0, -2.0) for fathers/mothers, respectively. Maternal age of menarche was significantly associated with the onset of all pubertal milestones except PH2+ in girls.

CONCLUSIONS

Maternal as well as paternal pubertal timing was a strong determinant of age at pubertal onset in both girls and boys. Age at breast and pubic hair development in girls, which has declined most during recent years, seemed to be least dependent on heritability.

Pubertal development in healthy children is mirrored by DNA methylation patterns in peripheral blood

Puberty marks numerous physiological processes which are initiated by central activation of the hypothalamic–pituitary–gonadal axis, followed by development of secondary sexual characteristics. To a large extent, pubertal timing is heritable, but current knowledge of genetic polymorphisms only explains few months in the large inter-individual variation in the timing of puberty. We have analysed longitudinal genome-wide changes in DNA methylation in peripheral blood samples (n = 102) obtained from 51 healthy children before and after pubertal onset. We show that changes in single methylation sites are tightly associated with physiological pubertal transition and altered reproductive hormone levels. These methylation sites cluster in and around genes enriched for biological functions related to pubertal development. Importantly, we identified that methylation of the genomic region containing the promoter of TRIP6 was co-ordinately regulated as a function of pubertal development. In accordance, immunohistochemistry identified TRIP6 in adult, but not pre-pubertal, testicular Leydig cells and circulating TRIP6 levels doubled during puberty. Using elastic net prediction models, methylation patterns predicted pubertal development more accurately than chronological age. We demonstrate for the first time that pubertal attainment of secondary sexual characteristics is mirrored by changes in DNA methylation patterns in peripheral blood. Thus, modulations of the epigenome seem involved in regulation of the individual pubertal timing.

DNA methylation of LINE-1 and Alu repetitive elements in relation to sex hormones and pubertal timing in Mexican-American children

BACKGROUND

The molecular mechanisms linking environmental exposures to earlier pubertal development are not well characterized. Epigenetics may play an important role, but data on the relationship between epigenetic marks and puberty, particularly in humans, is limited.

METHODS

We used pyrosequencing to measure Alu and long interspersed nucleotide elements (LINE-1) methylation in DNA isolated from whole blood samples collected from newborns and 9-y-old children (n = 266). Tanner staging was completed six times between ages 9 and 12 y to determine pubertal status, and hormone levels were measured in 12-y-old boys.

RESULTS

Among girls, we observed a suggestive trend of increased odds of breast and pubic hair development with higher Alu and LINE-1 methylation in 9-y-old blood, respectively. The strongest association identified was an inverse association of LINE-1 methylation in 9-y-old girls with odds of experiencing menarche by age 12 (OR (95% CI): 0.63 (0.46, 0.87); P = 0.005). We observed a consistent inverse relationship for Alu and LINE-1 methylation at 9 y with luteinizing hormone (LH), testosterone and follicle-stimulating hormone levels in boys but it was only significant between LINE-1 and LH.

CONCLUSION

DNA methylation of Alu and LINE-1 may be involved in puberty initiation and development. This relationship should be confirmed in future studies.

Recent advances in the understanding and management of delayed puberty

Delayed puberty, especially in boys, is a common presentation in paediatrics. Recent advances have improved our understanding of the neuroendocrine, genetic and environmental factors controlling pubertal development, and hence inform the pathophysiology of delayed puberty. The discovery of kisspeptin signalling through its receptor identified neuroendocrine mechanisms controlling the gonadotrophin-releasing hormone (GnRH) pulse generator at the onset of puberty. Genetic mechanisms from single gene mutations to single nucleotide polymorphism associated with delayed puberty are being identified. Environmental factors, including nutritional factors and endocrine disruptors, have also been implicated in changes in secular trends and abnormal timing of puberty. Despite these advances, the key clinical question is to distinguish delayed puberty associated with an underlying pathology or hypogonadism from constitutional delay in growth and puberty, which remains challenging as biochemical tests are not always discriminatory. The diagnostic accuracies of newer investigations, including 36-hour luteinising hormone releasing hormone (LHRH) tests, GnRH-agonist tests, antimullerian hormone and inhibin-B, require further evaluation. Sex hormone replacement remains the main available treatment for delayed puberty, the choice of which is largely dictated by clinical practice and availability of the various sex steroid preparations. Spontaneous reversal of hypogonadism has been reported in boys with idiopathic hypogonadotrophic hypogonadism after a period of sex steroid treatment, highlighting the importance of reassessment at the end of pubertal induction. Novel therapies with a more physiological basis such as gonadotrophins or kisspeptin-agonist are being investigated for the management of hypogonadotrophic hypogonadism. Careful clinical assessment and appreciation of the normal physiology remain the key approach to patients with delayed puberty.

Causes, diagnosis, and treatment of central precocious puberty

Central precocious puberty results from the premature activation of the hypothalamic-pituitary-gonadal axis. It mimics physiological pubertal development, although at an inappropriate chronological age (before 8 years in girls and 9 years in boys). It can be attributable to cerebral congenital malformations or acquired insults, but the cause in most cases in girls remains unknown. MKRN3 gene defects have been identified in familial disease, with important basic and clinical results. Indeed, genetic analysis of this gene should be included in the routine clinical investigation of familial and idiopathic cases of central precocious puberty. Gonadotropin-releasing hormone agonists are the gold-standard treatment. The assessment and management of this disease remain challenging for paediatric endocrinologists. In this Series paper, we describe current challenges involving the precise diagnosis and adequate treatment of this disorder.

Pubertal development and regulation

Puberty marks the end of childhood and is a period when individuals undergo physiological and psychological changes to achieve sexual maturation and fertility. The hypothalamic-pituitary-gonadal axis controls puberty and reproduction and is tightly regulated by a complex network of excitatory and inhibitory factors. This axis is active in the embryonic and early postnatal stages of life and is subsequently restrained during childhood, and its reactivation culminates in puberty initiation. The mechanisms underlying this reactivation are not completely known. The age of puberty onset varies between individuals and the timing of puberty initiation is associated with several health outcomes in adult life. In this Series paper, we discuss pubertal markers, epidemiological trends of puberty initiation over time, and the mechanisms whereby genetic, metabolic, and other factors control secretion of gonadotropin-releasing hormone to determine initiation of puberty.

Genetic variations altering FSH action affect circulating hormone levels as well as follicle growth in healthy peripubertal girls

STUDY QUESTION

Do variants of the genes encoding follicle stimulating hormone (FSH) beta subunit (B) and FSH receptor (R) impact circulating reproductive hormone levels and ovarian follicle maturation in healthy peripubertal girls?

SUMMARY ANSWER

FSHB and FSHR genetic variants exert, alone or their combination, distinct effects on reproductive hormone levels as well as ovarian follicle maturation in healthy peripubertal girls.

WHAT IS KNOWN ALREADY

FSHB and FSHR genetic variants impact reproductive hormone levels as well as associated pathologies in women. While FSHR c. 2039A>G is known to alter gonadotrophin levels in women, FSHR c.-29G>A has not yet been shown to exert effect and there are conflicting results concerning FSHB c.-211G>T.

STUDY DESIGN, SIZE, DURATION

This population-based study included 633 girls recruited as part of two cohorts, the COPENHAGEN Puberty Study (2006-2014, a cross-sectional and ongoing longitudinal study) and the Copenhagen Mother-Child Cohort (1997-2002, including transabdominal ultrasound (TAUS) of the ovaries in a subset of 91 peripubertal girls).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Clinical examinations, including pubertal breast stage (Tanner's classification B1-B5) were performed. Circulating levels of FSH, luteinizing hormone (LH), estradiol, anti-Mullerian hormone (AMH) and inhibin-B were assessed by immunoassays. In a subset of the girls (n = 91), ovarian volume and the number/size of antral follicles were assessed by TAUS. Genotypes were determined by competitive PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

FSHR c.2039A>G minor alleles were positively associated with serum FSH (β = 0.08, P = 0.004), LH (β = 0.06, P = 0.012) and estradiol (β = 0.06, P = 0.017) (adjusted for Tanner stages). In a combined model, FSHR c.-29G>A and FSHR c.2039A>G alleles were positively associated with FSH levels in early-pubertal girls (B2 + B3, n = 327, r = 0.1, P = 0.02) and in young adolescents (B4 + B5, n = 149, r = 0.2, P = 0.01). Serum AMH and inhibin B levels were not significantly influenced by the single nucleotide polymorphisms (SNPs). Single SNPs were not associated with follicles counts, however, a cumulative minor allele count (FSHB c.-211 G>T and FSHR c.-29G>A) was negatively associated with the number of large follicles (≥5 mm) (n = 91, P = 0.04) (adjusted for Tanner stages).

LIMITATIONS, REASONS FOR CAUTION

Since we studied girls and young adolescents during pubertal transition, our study may not be fully comparable with previous studies on FSHB and FSHR variants in adult women. The group of young adolescents (Tanner B4 + B5) reflects the endocrine situation in adult women best, however, the group is not large enough to contribute substantially to the conflicting results concerning the influence of FSHB c.-211G>T in adult women. Furthermore, we have no information about the exact day of the menstrual cycle in the subgroup of girls with menarche.

WIDER IMPLICATIONS OF THE FINDINGS

The sex-specific interaction of FSHB and FSHR genetic variants and physiological as well as pathological conditions is being increasingly elucidated. The variant triplet set might serve as diagnostic and pharmacogenetic marker. For the first time, we show an additional effect of FSHR c.-29G>A on serum FSH levels in healthy girls. Moreover, morphological data suggest impaired FSH-induced maturation of ovarian follicles in minor allele carriers of FSHB c.-211G>T and FSHR c.-29G>A. This may explain previous findings of delayed pubertal onset in these girls.

STUDY FUNDING/COMPETING INTERESTS

Funding was provided by the Danish Agency for Science, Technology and Innovation (09-067180), Danish Ministry of the Environment, CeHoS (MST-621-00065), Capital Region of Denmark (December 2011), Ministry of Higher Education and Science (DFF-1331-00113) and EDMaRC (Danish Ministry of Health). A.S.B. was funded from December 2015 by ReproUnion (EU Interreg Öresund-Kattegat-Skagerrak). The authors declare no conflict of interest.

Increasing incidence of premature thelarche in the Central Region of Denmark - Challenges in differentiating girls less than 7 years of age with premature thelarche from girls with precocious puberty in real-life practice

Background

Premature thelarche (PT) seems to be increasing and it is difficult to differentiate its early stages from precocious puberty (PP). Clinical and biochemical parameters are warranted to differentiate the two diagnoses.

Methods

One hundred ninety-one girls aged 0.5–7 years were included. Diagnoses were validated and the girls were categorized to the groups PP (n = 27) and PT (n = 164). Anthropometry, Tanner stages, ethnicity, bone age, and biochemistry, were recorded. Conventional variables for diagnosing PP were compared between the groups at time of referral to identify parameters predictive for the diagnosis.

Results

The referral rate of PT increased from 1998–2013. Girls with PT and PP differed with regards to age at referral, body mass index standard deviation scores (BMISDS), ethnicity, bone age advancement, basal luteinizing hormone (LH), gonadotropin releasing hormone (GnRH) stimulated LH and follicle stimulating hormone (FSH), basal and stimulated LH/FSH ratio, and sex-hormone binding globulin (SHBG). Apart from SHBG there was considerable overlap of the variables between the PT and the PP groups.

Conclusions

First, the incidence of PT appears to increase. Second, SHBG was the variable which best discriminated PT from PP. Third, stimulated LH in 1–3 years old girls with PT is similar to stimulated LH in 5–7 years old girls with PP. Age, BMISDS, ethnicity, bone age, stimulated gonadotropins and LH/FSH and SHBG are all useful variables for differentiating PP from PT. However normative data for stimulated LH and FSH in the age group 0.5–7 years are warranted.

Earlier menarcheal age in Spanish girls is related with an increase in body mass index between pre-pubertal school age and adolescence

BACKGROUND

Higher body mass index (BMI) has been associated with earlier pubertal development.

OBJECTIVE

The aim of this longitudinal study was to determine menarcheal age in a Spanish cohort and to assess its association with anthropometric variables at birth, childhood and adolescence. We also analyse whether the tracking of weight between different ages could affect the timing of menarche.

METHODS

The sample population included 195 randomly selected 6-8-year-old girls who participated in the baseline of the Four Provinces Study and in the follow-up of this study at 13-16 years old. Anthropometrical variables were measured and BMI and BMI z-score were calculated. Information regarding birth weight and menarche was obtained by means of self-report questionnaire.

RESULTS

Correlation analysis showed a significant negative association of age at menarche with weight, BMI and BMI z-score in the baseline and follow-up groups but not with weight at birth. Fat mass at adolescence is related to a significantly earlier menarcheal age. When comparing weight categories, earliest menarcheal age is associated with an increase of BMI between 6-8-year-old and 13-16-year-old girls.

CONCLUSION

In our study, high weight in girls is associated with the earliest age at menarche. This becomes a major influence when weight gain occurs between pre-pubertal school age and adolescence.

Ultrasensitive estrogen levels at 7 years of age predict earlier thelarche: evidence from girls of the growth and obesity Chilean cohort

OBJECTIVE

Prepubertal estradiol equivalents have been inconsistently linked to age at thelarche; elucidating this relationship becomes relevant given the worldwide decline in the age of puberty onset. Thus, our aim is to assess whether prepubertal girls with higher serum levels of estradiol equivalents at age 7 have a greater risk of presenting early thelarche (ET).

DESIGN

Nested case-control study within the Growth and Obesity Cohort Study of 1196 low-middle income children (∼50% girls) from Santiago, Chile. Girls were defined as cases (ET; n=61) if breast bud appeared prior to 8 years of age; controls (n=91) had thelarche >8 years.

METHODS

At 6.7 years, weight, height and waist circumference were measured and a fasting blood sample was obtained for measuring estrogen equivalent (ultrasensitive recombinant cell bioassay), DHEAS, leptin, insulin and IGF1. Beginning at 7 years old, Tanner staging was assessed prospectively twice a year and the appearance of breast bud was assessed by palpation.

RESULTS

Mean serum estradiol-equivalent at 6.7 years was 3.9±3.6 pg/ml for cases and 3.6±2.3 pg/ml for controls. Girls with ET had a higher risk of presenting elevated estradiol-equivalent (≥5 pg/ml) at 7 years (OR=2.05, 95% CI: 0.96-4.36) than controls that was borderline significant. However, after adjusting by BMI, insulin and IGF1 at age 7, the association between estradiol-equivalent and ET was significant (OR=2.29 (95% CI: 1.05-5.01)).

CONCLUSIONS

Chilean girls from low to middle socioeconomic status with ET exhibited double the risk of having high levels of estradiol-equivalent at 7 years than girls with a later age of thelarche. Whole-body adiposity and increased adrenal activity did not explain the observed prepubertal estrogen increase.