Puberty, obesity and ethnicity

New liquid chromatography tandem mass spectrometry reference data for estradiol show mini-puberty in both sexes and typical pre-pubertal and pubertal patterns

CONTEXT

Reliable estradiol (E2) reference intervals (RIs) are crucial in pediatric endocrinology.

OBJECTIVES

This study aims to develop a sensitive ultra-performance liquid chromatographic tandem mass spectrometry (UPLC-MS/MS) method for E2 in serum, to establish graphically represented RI percentiles and annual RIs for both sexes, and to perform a systematic literature comparison.

METHODS

First, a UPLC-MS/MS method for E2 was developed. Second, graphically represented RI percentiles and annual RIs covering 0-18 years were computed (cohort of healthy children [1181 girls and 543 boys]). Subsequently, RIs were compared with published data by systematic searches.

RESULTS

Lower limit of quantification was 11 pmol/L, indicating high sensitivity. Estradiol first peaked during mini-puberty in both sexes (girls up to 192 pmol/L; boys up to 225 pmol/L). As could be expected, girls showed higher pubertal E2 (up to 638 pmol/L). However, boys' RIs (up to 259 pmol/L) overlapped considerably. We found 4 studies in the literature that also used LC-MS/MS to determine E2 and published RIs for the complete pediatric age range. Reference intervals varied considerably. Pre-pubertal and pubertal phases were present in all studies. Higher E2 during the time of mini-puberty in both sexes was documented in 3 studies including ours.

CONCLUSIONS

Variability of RIs for E2 between studies illustrates the importance of laboratory-specific RIs despite using a LC-MS/MS reference method. In boys, the striking E2 peak during mini-puberty as well as high pubertal E2 without phenotypic estrogenization in regular male puberty indicates that the role of E2 in children and, especially in boys, requires better functional understanding.

The impacts of early environmental adversity on cognitive functioning, body mass, and life-history behavioral profiles

Early adverse experiences or exposures have a profound impact on neurophysiological, cognitive, and somatic development. Evidence across disciplines uncovers adversity-induced alternations in cortical structures, cognitive functions, and related behavioral manifestations, as well as an energetic trade-off between the brain and body. Based on the life history (LH) framework, the present research aims to explore the adversity-adapted cognitive-behavioral mechanism and investigate the relation between cognitive functioning and somatic energy reserve (i.e., body mass index; BMI). A structural equation modeling (SEM) analysis was performed with longitudinal self-reported, anthropometric, and task-based data drawn from a cohort of 2,607 8- to 11-year-old youths and their primary caregivers recruited by the Adolescent Brain Cognitive Development (ABCDSM) study. The results showed that early environmental adversity was positively associated with fast LH behavioral profiles and negatively with cognitive functioning. Moreover, cognitive functioning mediated the relationship between adversity and fast LH behavioral profiles. Additionally, we found that early environmental adversity positively predicted BMI, which was inversely correlated with cognitive functioning. These results revealed an adversity-adapted cognitive-behavioral mechanism and energy-allocation pathways, and add to the existing knowledge of LH trade-off and developmental plasticity.

Childhood adversity and accelerated reproductive events: a systematic review and meta-analysis

OBJECTIVE

Accelerated female reproductive events represent the early onset of reproductive events involving puberty, menarche, pregnancy loss, first sexual intercourse, first birth, parity, and menopause. This study aimed to explore the association between childhood adversity and accelerated female reproductive events.

DATA SOURCES

PubMed, Web of Science, and Embase were systematically searched from September 22, 2022 to September 23, 2022.

STUDY ELIGIBILITY CRITERIA

Observational cohort, cross-sectional, and case-control studies in human populations were included if they reported the time of reproductive events for female individuals with experience of childhood adversity and were published in English.

METHODS

Two reviewers independently screened studies, obtained data, and assessed study quality, and conflicts were resolved by a third reviewer. Dichotomous outcomes were evaluated using meta-analysis, and pooled odds ratios and 95% confidence intervals were generated using random-effects models. Moderation analysis and meta-regression were used to investigate heterogeneity.

RESULTS

In total, 21 cohort studies, 9 cross-sectional studies, and 3 case-control studies were identified. Overall, female individuals with childhood adversity were nearly 2 times more likely to report accelerated reproductive events than those with no adversity exposure (odds ratio, 1.91; 95% confidence interval, 1.33-2.76; I2=99.6%; P<.001). Moderation analysis indicated that effect sizes for the types of childhood adversity ranged from an odds ratio of 1.61 (95% confidence interval, 1.23-2.09) for low socioeconomic status to 2.13 (95% confidence interval, 1.14-3.99) for dysfunctional family dynamics. Among the 7 groups based on different reproductive events, including early onset of puberty, early menarche, early sexual initiation, teenage childbirth, preterm birth, pregnancy loss, and early menopause, early sexual initiation had a nonsignificant correlation with childhood adversity (odds ratio, 2.70; 95% confidence interval, 0.88-8.30; I2=99.9%; P<.001). Considerable heterogeneity (I2>75%) between estimates was observed for over half of the outcomes. Age, study type, and method of data collection could explain 35.9% of the variance.

CONCLUSION

The literature tentatively corroborates that female individuals who reported adverse events in childhood are more likely to experience accelerated reproductive events. This association is especially strong for exposure to abuse and dysfunctional family dynamics. However, the heterogeneity among studies was high, requiring caution in interpreting the findings and highlighting the need for further evaluation of the types and timing of childhood events that influence accelerated female reproductive events.

Standardization of Weightage Assigned to Different Segments of the Hand X-ray for Assessment of Bone Age by the Greulich-Pyle Method

Introduction

Bone age (BA) assessment is important in evaluating disorders of growth and puberty; the Greulich and Pyle atlas method (GP) is most used. We aimed to determine the weightage to be attributed by raters to various segments of the hand x-ray, namely, distal end of radius-ulna (RU), carpals, and short bones for rating bone age using the GP atlas method.

Methods

692 deidentified x-rays from a previous study (PUNE-dataset) and 400 from the Radiological Society of North America (RSNA-dataset) were included in the study. Mean of BA assessed by experienced raters was termed reference rating. Linear regression was used to model reference age as function of age ratings of the three segments. The root-mean-square-error (RMSE) of segmental arithmetic mean and weighted mean with respect to reference rating were computed for both datasets.

Results

Short bones were assigned the highest weightage. Carpals were assigned higher weightage in pre-pubertal PUNE participants as compared to RSNA, vice-versa in RU segment of post-pubertal participants. The RMSE of weighted mean ratings was significantly lower than for the arithmetic mean in the PUNE dataset.

Conclusion

We thus determined weightage to be attributed by raters to segments of the hand x-ray for assessment of bone age by the GP method.

Risk Factors for Running-Related Injury in High School and Collegiate Cross-country Runners: A Systematic Review

OBJECTIVE: To summarize and describe risk factors for running-related injuries (RRIs) among high school and collegiate cross-country runners. DESIGN: Descriptive systematic review. LITERATURE SEARCH: Four databases (Scopus, SPORTDiscus, CINAHL, Cochrane) were searched from inception to August 2023. STUDY SELECTION CRITERIA: Studies assessing RRI risk factors in high school or collegiate runners using a prospective design with at least 1 season of follow-up were included. DATA SYNTHESIS: Results across each study for a given risk factor were summarized and described. The NOS and GRADE frameworks were used to evaluate quality of each study and certainty of evidence for each risk factor. RESULTS: Twenty-four studies were included. Overall, study quality and certainty of evidence were low to moderate. Females or runners with prior RRI or increased RED-S (relative energy deficiency in sport) risk factors were most at risk for RRI, as were runners with a quadriceps angle of >20° and lower step rates. Runners with weaker thigh muscle groups had increased risk of anterior knee pain. Certainty of evidence regarding training, sleep, and specialization was low, but suggests that changes in training volume, poorer sleep, and increased specialization may increase RRI risk. CONCLUSION: The strongest predictors of RRI in high school and collegiate cross-country runners were sex and RRI history, which are nonmodifiable. There was moderate certainty that increased RED-S risk factors increased RRI risk, particularly bone stress injuries. There was limited evidence that changes in training and sleep quality influenced RRI risk, but these are modifiable factors that should be studied further in this population. J Orthop Sports Phys Ther 2024;54(2):1-13. Epub 16 November 2023. doi:10.2519/jospt.2023.11550.

The Congenital and Acquired Mechanisms Implicated in the Etiology of Central Precocious Puberty

The etiology of central precocious puberty (CPP) is multiple and heterogeneous, including congenital and acquired causes that can be associated with structural or functional brain alterations. All causes of CPP culminate in the premature pulsatile secretion of hypothalamic GnRH and, consequently, in the premature reactivation of hypothalamic-pituitary-gonadal axis. The activation of excitatory factors or suppression of inhibitory factors during childhood represent the 2 major mechanisms of CPP, revealing a delicate balance of these opposing neuronal pathways. Hypothalamic hamartoma (HH) is the most well-known congenital cause of CPP with central nervous system abnormalities. Several mechanisms by which hamartoma causes CPP have been proposed, including an anatomical connection to the anterior hypothalamus, autonomous neuroendocrine activity in GnRH neurons, trophic factors secreted by HH, and mechanical pressure applied to the hypothalamus. The importance of genetic and/or epigenetic factors in the underlying mechanisms of CPP has grown significantly in the last decade, as demonstrated by the evidence of genetic abnormalities in hypothalamic structural lesions (eg, hamartomas, gliomas), syndromic disorders associated with CPP (Temple, Prader-Willi, Silver-Russell, and Rett syndromes), and isolated CPP from monogenic defects (MKRN3 and DLK1 loss-of-function mutations). Genetic and epigenetic discoveries involving the etiology of CPP have had influence on the diagnosis and familial counseling providing bases for potential prevention of premature sexual development and new treatment targets in the future. Global preventive actions inducing healthy lifestyle habits and less exposure to endocrine-disrupting chemicals during the lifespan are desirable because they are potentially associated with CPP.

Linking brain maturation and puberty during early adolescence using longitudinal brain age prediction in the ABCD cohort

The temporal characteristics of adolescent neurodevelopment are shaped by a complex interplay of genetic, biological, and environmental factors. Using a large longitudinal dataset of children aged 9-13 from the Adolescent Brain Cognitive Development (ABCD) study we tested the associations between pubertal status and brain maturation. Brain maturation was assessed using brain age prediction based on convolutional neural networks and minimally processed T1-weighted structural MRI data. Brain age prediction provided highly accurate and reliable estimates of individual age, with an overall mean absolute error of 0.7 and 1.4 years at the two timepoints respectively, and an intraclass correlation of 0.65. Linear mixed effects (LME) models accounting for age and sex showed that on average, a one unit increase in pubertal maturational level was associated with a 2.22 months higher brain age across time points (β = 0.10, p < .001). Moreover, annualized change in pubertal development was weakly related to the rate of change in brain age (β = .047, p = 0.04). These results demonstrate a link between sexual development and brain maturation in early adolescence, and provides a basis for further investigations of the complex sociobiological impacts of puberty on life outcomes.

Clinical profile and aetiologies of delayed puberty: a 15 years' experience from a tertiary centre in Sudan

OBJECTIVES

Delayed puberty is a common presentation to endocrine clinics, with adult height, sexual capability and fertility being the main concerns for the child and his/her family. Presentation is variable including short stature and/or absence of secondary sexual characteristics. The aetiology can either be constitutional, functional or permanent hypogonadotropic hypogonadism, permanent hypergonadotropic hypogonadism or unclassified. Despite the importance of this subject, there are no publications from Sudan.

METHODS

A retrospective hospital-based study. Records of all patients who were seen in the endocrinology unit at Gaffar Ibn Auf Children's Hospital and were diagnosed as having delayed puberty were reviewed and demographic, clinical, and investigations data were obtained.

RESULTS

A total of 136 patients were included in this study. Presentation includes short stature in 52.2%, both short stature and delayed puberty in 27.2%, and delayed puberty in 20.6%. The most common aetiologies were permanent hypogonadotropic hypogonadism and functional hypogonadotropic hypogonadism presented in 37.5% and 36% respectively, while constitutional delay of growth and puberty was found in only 14.7%. Type 1 diabetes mellitus (T1DM) was the most frequent chronic illness followed by coeliac disease. Hypergonadotropic hypogonadism was diagnosed in 11.7%, the majority of which were females.

CONCLUSIONS

The aetiological pattern reported in this series highlights the role of nutrition and general well-being in pubertal development, as well as the major impact of genetics and consanguinity on disease patterns. Data from African countries are limited and this is the first reported cohort on delayed puberty from Sudan.

Effects of Early Life Adversity on Pubertal Timing and Tempo in Black and White Girls: The National Growth and Health Study

OBJECTIVE

Although exposure to abuse in early life predicts earlier pubertal timing, especially for girls, it is unclear if this association generalizes to nonabuse stressors. In addition, the impact of race on the stress-maturation association remains unknown. To address these issues, we examined whether race moderates the effects of early adversity on pubertal timing and tempo using a longitudinal study design.

METHODS

In a cohort of 9- and 10-year-old Black and White girls, pubertal (areolar and pubic hair) maturation was assessed annually for 7 years. In adulthood, 368 participants (186 Black, 182 White) reported on abuse and nonabuse stressors they experienced from ages 0 to 12 years.

RESULTS

Early life abuse was associated with earlier pubertal timing, as indexed by younger age at menarche (b = -0.22, p = .005, 95% confidence interval [CI] = -0.39 to -0.06) and greater pubic hair development (b = 0.11, p = .003, 95% CI = 0.04 to 0.18), in addition to slower pubertal tempo, as indexed by slower rate of pubic hair (b = -0.03, p < .001, 95% CI = -0.05 to -0.01) and areolar (b = -0.02, p = .02, 95% CI = -0.03 to -0.003) development. These associations were not found for nonabuse adversity. Black girls with early life abuse had greater pubic hair development (b = 0.23, p < .001, 95% CI = 0.12 to 0.35) and were slower in pubic hair tempo (b = -0.07, p < .001, 95% CI = -0.09 to -0.04) than their White counterparts.

CONCLUSIONS

Screening for early life abuse may help address health disparities related to earlier pubertal timing.

Sexual maturity assessment in Indian children-a study from western India

OBJECTIVES

Pubertal assessment is crucial as puberty is the transition from childhood to adulthood. Pubertal assessment, growth, and secular trend in puberty need to be explored further in India. The objectives were to assess Sexual Maturity Rating (SMR) among children and establish normative data of puberty from western India. We also compared age of attainment of various stages of puberty with BMI and secular trend in menarche.

METHODS

A cross-sectional observational study was undertaken at a tertiary care pediatric center. The study population were healthy girls and boys between 6 and 18 years. Demographic data was noted. Anthropometry and SMR assessment (Tanner staging) were performed. The age of menarche was noted among the girls and their mothers. Data were analyzed using SPSS 21.

RESULTS

In girls, median age of thelarche, pubarche, and menarche was 9.37 (8.5-10.2), 10.18 (9.87-10.49), and 12.55 years (12.41-12.75) respectively. There was an early appearance of thelarche but menarche was delayed in overweight-obese girls (statistically not significant). Age of menarche showed a shift to left in girls as compared to their mothers (p=0.036). In boys, median age of testicular stage 2 and pubarche was 10.7 (9.9-11.8) and 11.6 years (11.1-12.1) respectively. In overweight-obese boys the pubertal milestones were achieved earlier (statistically not significant).

CONCLUSIONS

Normative data on pubertal assessment from western India is presented. Age of menarche shows a shift to left in girls as compared to their mothers. Pubertal milestones were observed at a younger age in overweight obese children which was not significant.

Body composition analysis and references in children: clinical usefulness and limitations

The prevalence of obesity is increasing over the world. Especially in Asians compared to Caucasians, there has been a significant increase in the population with major chronic diseases. This has developed over a shorter time period which is associated with socioeconomic changes in recent decades and a greater predisposition to cardiometabolic disorders. Many Asians could be classified has having normal weight but with obesity as evidenced by body composition (BC) and fat distribution. Overweight in Asian adults is classified as a BMI > 23 kg/m² and obesity as a BMI > 25 kg/m². An effective strategy to manage the obesity epidemic by focusing on childhood obesity is needed because of the huge impact that obesity exerts on population health. However, monitoring tools are limited to anthropometry such as BMI and BMI z-scores which define overweight and obese as a BMI exceeding the 85th and 95th percentiles, respectively, on reference growth charts. To overcome the limitations of BMI, reference values for BC components have been produced using various techniques. The use of BC charts for children in personalized therapeutic approach has increased, although there is a lack of a consensus on a single reference technique. Zones on BC charts and the personalized values of BC components could be practical, especially for the detection of metabolically unhealthy normal weight (MUN) children. BC charts should be included in the growth chart package and BC monitoring through the entire life course will help us understand the association between growth, aging, health and disease.

Is age of menarche related to urinary symptoms in young Jordanian girls? A prospective cross-sectional study

Objectives

Methods

Results

Conclusion

Endocrinology of human female sexuality, mating, and reproductive behavior

Hormones orchestrate and coordinate human female sexual development, sexuality, and reproduction in relation to three types of phenotypic changes: life history transitions such as puberty and childbirth, responses to contextual factors such as caloric intake and stress, and cyclical patterns such as the ovulatory cycle. Here, we review the endocrinology underlying women's reproductive phenotypes, including sexual orientation and gender identity, mate preferences, competition for mates, sex drive, and maternal behavior. We highlight distinctive aspects of women's sexuality such as the possession of sexual ornaments, relatively cryptic fertile windows, extended sexual behavior across the ovulatory cycle, and a period of midlife reproductive senescence-and we focus on how hormonal mechanisms were shaped by selection to produce adaptive outcomes. We conclude with suggestions for future research to elucidate how hormonal mechanisms subserve women's reproductive phenotypes.

Plasma kisspeptin and ghrelin levels in puberty variant cases

BACKGROUND

The aim of this study was to determine the serum levels of kisspeptin and ghrelin (GAH), as well as the relationship of these two peptides with each other in premature thelarche (PT) and premature adrenarche (PA) cases and to investigate the possibility of using these peptides as markers in the differentiation of puberty disorders.

METHODS

A PT group aged 1-8 years (n = 40), a PA group aged 1-9 years (n = 23, female/male = 20/3) and control groups consistent with each of the previous groups in terms of age and gender were created for the study. Kisspeptin and ghrelin levels were measured with ELISA methods from blood samples drawn while fasting in the morning.

RESULTS

When the PT group was compared with the controls, the plasma kisspeptin levels of the cases were significantly higher than the control group (165.47 ± 15.45 pmol/L, 96.82 ± 12.33 pmol/L, p = 0.005, respectively). Kisspeptin levels in the PA group did not show a difference with the control group (121.36 ± 17.99 pmol/L, 95.52 ± 11.54 pmol/L, p = 0.249, respectively). No significant difference could be found when GAH levels in the PT and PA groups were compared with controls. No significant correlation was found between kisspeptin and GAH levels in the PT and PA groups.

CONCLUSIONS

Our results indicate that kisspeptin plays an important role in the PT, but GAH is not associated with puberty disorders.

Development and Lability in the Parent-Child Relationship During Adolescence: Associations With Pubertal Timing and Tempo

Adolescents' and parents' reactions to pubertal development are hypothesized to contribute to changes in family dynamics. Using 7-year longitudinal data from the NICHD-SECCYD (488 boys, 475 girls) we examined relations between pubertal development (timing, tempo) and trajectories (developmental change and year-to-year lability) of parent-child conflict and closeness from age 8.5 to 15.5 years. Changes were mostly characterized by year-to-year fluctuations - lability. Parent-child conflict increased and closeness decreased some with age. Pubertal timing and tempo were more consistently associated with lability in parent-child relationships than with long-term trends, although faster tempo was associated with steeper decreases in parent-child closeness. Findings provide a platform for examining how puberty contributes to both long-term and transient changes in adolescents' relationships and adjustment.

Developmental Programming: Prenatal and Postnatal Androgen Antagonist and Insulin Sensitizer Interventions Prevent Advancement of Puberty and Improve LH Surge Dynamics in Prenatal Testosterone-Treated Sheep

Prenatal T excess induces maternal hyperinsulinemia, early puberty, and reproductive/metabolic defects in the female similar to those seen in women with polycystic ovary syndrome. This study addressed the organizational/activational role of androgens and insulin in programming pubertal advancement and periovulatory LH surge defects. Treatment groups included the following: 1) control; 2) prenatal T; 3) prenatal T plus prenatal androgen antagonist, flutamide; 4) prenatal T plus prenatal insulin sensitizer, rosiglitazone; 5) prenatal T and postnatal flutamide; 6) prenatal T and postnatal rosiglitazone; and 7) prenatal T and postnatal metformin. Prenatal treatments spanned 30-90 days of gestation and postnatal treatments began at approximately 8 weeks of age and continued throughout. Blood samples were taken twice weekly, beginning at approximately 12 weeks of age to time puberty. Two-hour samples after the synchronization with prostaglandin F2α were taken for 120 hours to characterize LH surge dynamics at 7 and 19 months of age. Prenatal T females entered puberty earlier than controls, and all interventions prevented this advancement. Prenatal T reduced the percentage of animals having LH surge, and females that presented LH surge exhibited delayed timing and dampened amplitude of the LH surge. Prenatal androgen antagonist, but not other interventions, restored LH surges without normalizing the timing of the surge. Normalization of pubertal timing with prenatal/postnatal androgen antagonist and insulin sensitizer interventions suggests that pubertal advancement is programmed by androgenic actions of T involving insulin as a mediary. Restoration of LH surges by cotreatment with androgen antagonist supports androgenic programming at the organizational level.

Association of pediatric obesity and migraine with comparison to tension headache and samples from other countries

The link between body weight and headache has hardly been examined in children. The aim was to evaluate the association of obesity and migraine in selected pediatric patients and compare the findings with the literature. Data on clinical symptoms, headache type, and body mass index standard deviation score were derived from the medical files of 245 patients with migraine and 87 with tension headache. Comparison of the 3 subgroups of migraine patients of normal weight, overweight, and obese with the corresponding body mass index standard deviation score subgroups of patients with tension-type headache yielded no statistically significant differences in frequency of headache attacks per month, or duration of headache attacks in hours. These results call into question earlier reports linking headache and obesity in children. Differences in findings between our study and those in the literature highlight several factors that should be addressed in further studies. A larger sample size may reveal more significant results.

Adolescent sleep disparities: sex and racial/ethnic differences

OBJECTIVES

During adolescence, significant changes occur in sleep (eg, decreased sleep duration and increased sleep problems). To date, few studies have examined whether self-reported sleep duration differences exist between races/ethnicities in early adolescence (ages 11-14 years).

METHODS

This study compared sexes and race/ethnicity groups on self-reported sleep duration in a large (n = 1543; 48.9% boys) racially/ethnically diverse (62.7% White, 23.7% Hispanic/Latino, 10.4% African American, and 3.2% Asian) sample of young adolescents (mean age, 12.31) drawn from local middle schools.

RESULTS

A 2-way analysis of variance revealed that there was a trend for a significant sex effect (P = .067, partial χ² = .002), with boys reporting more sleep than girls and significant race/ethnicity effects (P < .001, partial χ² = .012), with Hispanic and African American students reporting shorter sleep duration than White and Asian students. The interaction between sex × race/ethnicity was significant (P = .014, partial χ² = .002), with post hoc tests revealing that Hispanic males demonstrated significantly shorter sleep duration than White and Asian males and African American females demonstrating significantly shorter sleep duration than White females.

CONCLUSIONS

Given the literature showing short sleep duration is related to various negative health outcomes and all-cause mortality, more research is needed to determine the factors involved in these disparities. Adolescent sleep disparities: sex and racial/ethnic differences.

Genome-wide association studies of age at menarche and age at natural menopause

Genome-wide association studies (GWAS) have been successful in uncovering genetic determinants of age at menarche and age at natural menopause. To date, more than 30 novel genetic loci have been identified in GWAS for age at menarche and 17 for age at natural menopause. These findings have stimulated a plethora of follow-up studies particularly with respect to the functional characterization of these novel loci and how these results can be translated into risk prediction. However, the genetic loci identified so far account for only a small fraction of the overall heritability. This review provides an overview of the current state of our knowledge of the genetic basis of menarche and menopause timing. It emphasizes recent GWAS results and outlines strategies for discovering the missing heritability and strategies to further our understanding of the underlying molecular mechanisms of the observed genetic associations.

Menarcheal age of type 1 diabetic Bengali Indian females

BACKGROUND

It has been observed that menstrual characteristics are generally influenced by lifestyle, socio-cultural and biological factors.

AIM

The present study examines: (a) variation in menstrual characteristics between Type1 Diabetic females of rural and urban adolescents, i.e. the resident status; and (b) whether these characteristics can be predicted from various socio-economic, stress variables related to place of residence.

SUBJECTS AND METHODS

The sample of the present study constituted 103T1DM females from West Bengal, a State of India. These girls belong to a Bengali-speaking ethnic group. Data on socio-economic variables and menstrual characteristics were collected using pretested questionnaires.

RESULTS

Menstrual irregularity was common in our study participants, with age of menarche, but was not associated with current BMI, physical activity or insulin dose.

CONCLUSIONS

Our study displays that age at menarche is delayed in young women with T1DM compared to the concurrent overall mean age at menarche in the West Bengal population.

Age at menarche among in-school adolescents in Sawla Town, South Ethiopia

BACKGROUND

Although a declining trend in age at menarche has been observed in developed countries over decades commonly attributed to childhood excessive weight gain and sedentary life, little is known about this case in the developing countries.

METHODS

A cross-sectional study design and multistage sampling was used to include 660 school adolescents for analysis. Data collection included weight and height measurements. Multinomial logistic regression analyses were done for early and late age of menarche, in reference to average age at menarche, to measure the association of age at menarche with some socio-demographic variables and body habits.

RESULTS

The mean age at menarche was 13.9±1.2 years (95%CI, 13.8-14.0). The menarche ages ranged between 10 and 12 years for 10.5%, 13 and 14 years for 54.5%, and 15+ years for 35%. Low menarche age was independently associated with high calorie consumption, high protein diet, more coffee intake, low physical activity and parents' low educational background. Low body mass index, low parents' income, exercise, and Amhara ethnic background were associated with late menarche age.

COCLUSION

The mean menarche age found in this study was higher than the report from developed countries. But, the proportion of adolescents with low menarche age was comparable with reports from developed countries. Inactive adolescents were more likely to see menarche earlier than average age. Healthy eating habits, regular exercise and nutrition education need to be promoted among school children.

Gender comparisons of unhealthy weight-control behaviors among sixth-Graders

OBJECTIVE

To examine gender differences in unhealthy weight-control behaviors (UWCB) and identify key psychosocial and demographic correlates of UWCB among sixth-graders.

METHODS

A cross-sectional survey was completed by 146 boys and 153 girls at a middle school. Secondary data analyses included bivariate tests and multivariable logistic regression.

RESULTS

Forty-seven percent of participants reported 1 or more UWCB, with no differences by gender (P = .75). Factors common to boys and girls included: lower global self-esteem; lower body-esteem; and greater negative parental modeling among participants who engaged in UWCB compared to those who did not. However, multivariable models revealed gender differences. Among boys, body mass index, negative parental modeling, and global self-esteem retained statistically significant associations with UWCB after controlling for other variables in the model, whereas race and weight-related body-esteem remained significant for girls.

CONCLUSIONS AND IMPLICATIONS

This research highlights the need for gender-specific UWCB prevention programs implemented in late childhood and early adolescence.

Relationship between Breast Feeding and Obesity in Children with Low Birth Weight

Background

Breast feeding appears to play a role in determining obesity and abdominal obesity during childhood, specifically in children with a history of low birth weight.

Objective

The purpose of this study is to investigate the relation of breast-feeding with either of abdominal obesity and obesity among Iranian school children.

Materials and Methods

A total of 1184 students (625 girls and 559 boys), aged 10 to 13 years old, were selected from 112 governmental elementary schools in Iran. Height, weight, waist circumference and blood pressure were measured using standard instruments and a pretested standardized questionnaire was performed for compiling information about family economics and educational level, first–degree family history of obesity, history of breast feeding, food pattern and birth weight, as well.

Results

13.68% (n = 160) of students had a history of low birth weight, and 26.41% of them had abdominal obesity. Of all participants, 22.04% were overweight and 5.32% were obese which was more prevalent in girls than in boys (P = 0.03). First-degree family history of obesity (P = 0.001), excessive gestational weight gain (P = 0.001) and birth weight (P = 0.01) were significantly correlated with the prevalence of obesity and abdominal obesity during childhood. Moreover the prevalence of abdominal obesity in children with low birth weight was significantly correlated with breast feeding (P = 0.04); But this relation was not significantly about obesity in our participants (P = 0.9). Furthermore duration of breast feeding was significantly and inversely correlated with obesity and abdominal obesity in schoolchildren with low birth weight (P = 0.01).

Conclusions

The results suggest that Breast feeding and its long-term consequences were important factors for preventing metabolic syndrome criteria in childhood and later years of life span. With regard to the increasing prevalence of obesity in children, more research is urgently needed to clarify whether breast feeding have negative consequences for the risk of chronic disease in children, especially in children with low birth weight.

Concurrent and longitudinal associations between diurnal cortisol and body mass index across adolescence

PURPOSE

Childhood and adolescent obesity have reached epidemic levels; however, little is known about the psychobiological underpinnings of obesity in youth and whether these differ from the mechanisms identified in adults. The current study examines concurrent (i.e., measured at the same point in time) and longitudinal (i.e., using earlier cortisol measures to predict later body mass index [BMI]) associations between diurnal cortisol and BMI across adolescence.

METHODS

Adolescent diurnal cortisol was measured over 3 days at each 11, 13, and 15 years. Hierarchical linear modeling was used to extract average measures of predicted morning, afternoon, evening levels of cortisol and the diurnal slope at each assessment. Adolescent BMI (kg/m(2)) was measured at 11, 13, 15, and 18 years. Sex, family socioeconomic status, mother's BMI, pubertal status, and adolescent mental health were examined as possible confounding variables.

RESULTS

Linear regressions revealed that blunted patterns of adolescent cortisol were associated with increased measures of BMI across adolescence both concurrently and longitudinally, particularly when examining measures of cortisol in early adolescence. Multinomial logistic regressions extended the linear regression findings beyond BMI scores to encompass categories of obesity.

CONCLUSIONS

The current study builds on previous research documenting diurnal cortisol-obesity findings in adults by demonstrating similar findings exist both concurrently and longitudinally in adolescents. Findings suggest the association between cortisol and BMI is developmentally influenced and that blunted diurnal cortisol patterns can be identified in overweight individuals at a younger age than previously thought.

Prevalence of Overweight and Obesity among Adolescents in Seven Arab Countries: A Cross-Cultural Study

Objective. The aim of this study was to find out the prevalence of overweight and obesity among adolescents in seven Arab countries using similar reference standard. Methods. A school-based cross-sectional study was carried out in seven cities in Arab countries, namely, Algeria, Jordan, Kuwait, Libya, Palestine, Syria, and United Arab Emirates. A multistage stratified random sampling technique was used. The total sample included was 4698 adolescents aged from 15 to 18 years (2240 males, 2458 females). The International Obesity Task Force (IOTF) reference standard was used to classify the adolescents as nonobese, overweight, and obese. Results. Among males, overweight was highest among Kuwaiti adolescents (25.6%), followed by Jordanian (21.6%), and Syrian (19.7%) adolescents. Among females, the highest prevalence of overweight was reported in Libyan adolescents (26.6%), followed by Kuwaiti (20.8%), and Syrian (19.7%) adolescents. As for obesity, Kuwaiti adolescents showed the highest prevalence of obesity for both males (34.8%) and females (20.6%). Conclusion. There is an urgent need to establish a plan of action to combat obesity in schoolchildren in these countries.

Girls with early puberty attain a near-final height similar to their target height

BACKGROUND

The median age at thelarche in Thai girls has decreased from 10.3 to 9.4 years over the last 20 years. An age at thelarche of 7.0-9.0 years, which is earlier than in the general population, is considered as early puberty.

OBJECTIVE

To study the pattern of pubertal development in Thai girls with early puberty.

STUDY DESIGN

A total of 104 girls with breast development at 7.0-9.0 years who attended Songklanagarind Hospital between 2003 and 2005 were followed up until they attained their near-final height (NFH).

RESULTS

The mean age at initial evaluation was 8.5 +/- 1.0 years. The average age at menarche and on attaining NFH was 10.2 +/- 0.9 and 12.6 +/- 0.4 years, respectively. The average NFH was 154.0 +/- 4.9 cm, which was similar to the target height of 153.1 +/- 4.8 cm. Comparison of girls who were normal weight and obese (weight-for-height >120%) revealed that the latter had an earlier age at menarche (9.8 +/- 0.8 vs. 10.5 +/- 0.8 years, p<0.01) and reached their NFH at a younger age (12.2 +/- 0.4 vs. 12.9 +/- 0.4 years, p=0.02). However, normal-weight and obese girls reached approximately the same NFH (155.8 +/- 4.8 vs. 153.1 +/- 4.0 cm, p=0.058).

CONCLUSION

Girls with early puberty attained NFH similar to their genetic potential. Obese girls attained NFH at an earlier age and had the same NFH as normal-weight girls.

Thin adolescents: Who are they? What do they do? Socio-demographic and use-of-time characteristics

OBJECTIVES

Examine: (1) the anthropometric, socio-demographic and use-of-time characteristics of thin adolescents, and (2) compare these characteristics to other weight status categories.

METHODS

Data were from the 2007 National Children's Nutrition and Physical Activity Survey which collected data on a random sample of 2200 9 to 16 year old Australians from February to August 2007. Seven socio-demographic variables, anthropometric data (height and weight were measured) and nine use-of-time variables were used, and compared across the weight status categories. Physical activity was measured using pedometers and the Multimedia Activity Recall for Children and Adults.

RESULTS

5.3% of adolescents were classified as thin, a percentage which did not significantly vary by age, sex, indigenous status, household income, education level or family structure. Relative to other adolescents, thin adolescents were shorter and lighter. Thin adolescents were less active than their normal weight peers, but walked further and accumulated significantly less screen and TV time than obese adolescents.

CONCLUSION

Thin adolescents were found in similar proportions across all socio-demographic bands. Thin adolescents recorded similar physical activity levels to their normal weight peers, but were more active than obese adolescents. The findings from the study support in part the theory of thinness related developmental delay.

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.

Association between age at menarche and risk of diabetes in adults: results from the EPIC-Norfolk cohort study

AIMS/HYPOTHESIS

Earlier age at menarche is associated with increased BMI and obesity risk from early childhood through to adulthood. We hypothesised that earlier age at menarche would also predict subsequent diabetes risk.

METHODS

This was a population-based prospective cohort study of 13,308 women, who were aged 40 to 75 years between 1993 and 1997 and participating in the Norfolk cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Norfolk). We used data on age at menarche and ascertained diabetes incidence to 2005.

RESULTS

There were 734 cases of diabetes (363 incident and 371 prevalent cases). Mean age at menarche was lower in women with diabetes than in non-diabetic women (12.8 vs 13.0 years, p = 0.008). Compared with the earliest quintile (menarche at 8-11 years), women in the oldest quintile (menarche at 15-18 years) had lower BMI (25.5 vs 27.4 kg/m2, p < 0.0001) and a reduced risk of diabetes (OR 0.66 [95% CI 0.51-0.86] adjusted for age, family history, physical activity, smoking, occupational social class, parity and use of hormonal preparations). The association between age at menarche and diabetes was linear (adjusted OR 0.91 [95% CI 0.87-0.96] per 1 year later menarche) and appeared to be completely mediated by adult BMI or waist circumference (OR 0.98 [95% CI 0.93-1.03], further adjusted for BMI at age 40-75 years).

CONCLUSIONS/INTERPRETATION

Earlier age at menarche increases the risk of diabetes in women and this association appears to be mediated by increased adiposity. History of earlier menarche may help to identify women with increased subsequent risk of diabetes.

Onset of ovulation after menarche in girls: a longitudinal study

INTRODUCTION

Hypothalamic-pituitary axis maturity has been believed to be the rate-limiting step in the development of ovulatory menstrual cycles. We hypothesized that, given current nutritional conditions, hypothalamic-pituitary axis maturation would be relatively rapid in menarcheal girls.

METHODS

Daily urine and menstrual records were collected for 2 yr each from 10 girls aged 11-13 yr at study entry. Urinary excretion of LH, FSH, estradiol (E1c), and progesterone (Pdg) metabolites was measured using established ELISAs. An objective algorithm detected rises of LH, FSH, E1c, and Pdg consistent with follicular maturation and/or ovulation.

RESULTS

Nine of 10 girls enrolled into the study experienced the onset of menarche prior to or during the 2-yr collection period. LH and FSH surges, as well as small amplitude Pdg increments, were observed prior to menarche. Regular, ovulatory-appearing cycles with LH surges and gradually increasing and more sustained Pdg rises were observed over time after menarche, although duration of Pdg elevations remained shorter than in adult women (8.9 +/- 1.0 vs. 12.1 +/- 0.8 d, P = 0.043). E1c levels leading to LH/FSH surges were lower in perimenarcheal girls than adult controls, and bleeding episodes did not uniformly correlate with hormone patterns. Progressive increases in FSH and Pdg, but not LH or E1c, were observed in association with menarche.

CONCLUSION

Mature hormone patterns are established within several months of and even prior to menarche in normal-weight perimenarcheal girls. Factors determining menstrual bleeding in perimenarcheal girls may not be solely dependent on reproductive hormones or the neuroendocrine axis.

Endocrine disruptors and abnormalities of pubertal development

Onset and development of puberty is regulated by the neuroendocrine system. Population-based studies worldwide have observed secular trends towards earlier puberty development. These changes are apparently caused by environmental factors such as improved socio-economic status, improved health care and nutrition. However, they may also partly result from endocrine-disrupting chemicals in the environment. Epidemiological studies have investigated the relationship between pubertal development and exposure to endocrine-disrupting chemicals (polychlorinated biphenyls, polybrominated biphenyls, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, phthalate esters, furans and the pesticide endosulfan). Associations with both perinatal and postnatal exposure have been reported. Studies in experimental animals support some of these findings and point to differential endocrine regulatory mechanisms linked to pubertal development acting in the perinatal and the pre-pubertal period. Pubertal development is naturally associated with growth and body composition. There is increasing evidence for a link between prenatal development and pubertal onset. In girls born small for gestational age (SGA), pubertal onset and age at menarche often are advanced, especially if there has been an extensive catch-up growth during the first months of life. In utero growth retardation may have multiple causes including exposure to xenobiotic substances as was suggested for some endocrine-disrupting chemicals. An abnormal perinatal environment of children born SGA may alter the endocrine status and the sensitivity of the receptors for endocrine and metabolic signalling that may have effects on maturation of brain and gonads. However, the causal pathways and the molecular mechanisms that may link the pubertal growth pattern of children born SGA, pubertal development and endocrine-disrupting chemicals need further study.

Insulin--a growth hormone

Insulin is a peptide hormone with a high degree of homology with the insulin-like growth factor I (IGF-I). Its biological actions are interlaced with those of GH and IGF-I. The objective of this study is to review the growth promoting actions of insulin. The experimental evidence consists of the use of organ cultures of neonatal mice condilar cartilage insulin which stimulates the cartilage cell differentiation and maturation. Injection of insulin to hypohysectomized rats stimulated tibial growth. Clinical evidence is manifold. Babies with diabetes and hypoinsulinemia are short, whereas babies with hyperinsulinism are big. Children with idiopathic short stature have low insulin whereas obese children with hyperinsulinism are tall. Hypo-insulinized children with diabetes slow their growth until the insulin dose is optimized. It remains to be clarified whether insulin exerts its growth promoting actions via its own receptors, via the IGF-I receptors, or via a hybrid (insulin--IGF-I) receptor.

Obesity in adolescence: Implications in orthodontic treatment

The incidence of obesity is increasing in the United States and around the world, and it is likely that obese patients will present for orthodontic therapy in greater numbers in the future. The implications of obesity for psychosocial well-being, bone metabolism, craniofacial growth, and pubertal growth must be assessed in treating obese orthodontic patients. This review article focuses on the relevant issues concerning obesity in regard to orthodontic therapy.

Dietary intake among under-, normal- and overweight 9- and 15-year-old Estonian and Swedish schoolchildren

OBJECTIVES

To determine the differences in macronutrient and food group contribution to total food and energy intakes between Estonian and Swedish under-, normal- and overweight schoolchildren, and to estimate the association between diet and body mass index (BMI).

DESIGN

Cross-sectional comparison between Estonian and Swedish children and adolescents of different BMI groups.

SETTING

Twenty-five schools from one region in Estonia and 42 in two regions of central Sweden.

SUBJECTS

In total 2308 participants (1176 from Estonia and 1132 from Sweden), including 1141 children with a mean age of 9.6 +/- 0.5 years and 1167 adolescents with a mean age of 15.5 +/- 0.6 years.

RESULTS

Overweight was more prevalent among younger girls in Sweden (17.0 vs. 8.9%) and underweight among girls of both age groups in Estonia (7.9 vs. 3.5% in younger and 10.5 vs. 5.1% in older age group of girls). Compared with that of normal- and underweight peers, the diet of overweight Estonian children contained more energy as fat (36.8 vs. 31.7%) but less as carbohydrates, and they consumed more milk and meat products. Absolute BMI of Estonian participants was associated positively with energy consumption from eggs and negatively with energy consumption from sweets and sugar. Swedish overweight adolescents tended to consume more energy from protein and milk products. Risk of being overweight was positively associated with total energy intake and energy from fish or meat products. In both countries the association of overweight and biological factors (pubertal maturation, parental BMI) was stronger than with diet.

CONCLUSION

The finding that differences in dietary intake between under-, normal- and overweight schoolchildren are country-specific suggests that local dietary habits should be considered in intervention projects addressing overweight.

Overweight and obesity and their associated factors in adolescents in Tehran, Iran, 2004-2005

OVERVIEW

Obesity is a significant health crisis around the world. Of great concern are the data pointing to the recent increase in the prevalence of obesity irregardless of age group and country. Overweight and obesity in adolescence are markers of overweight and obesity in adults, respectively. Very little data are currently available on the prevalence of childhood obesity in Iran, and more research on the risk factors is required before preventive public health programs can be formulated and put into practice.

OBJECTIVE

The objective of this study was to quantify the prevalence of overweight and obesity and their associated factors in adolescent children living in Tehran.

MATERIALS AND METHODS

During a multistage stratified cluster sampling, 2900 students (1200 males and 1700 females) aged 11-17 years were selected from 20 secondary schools in the school year of 2004-2005. A questionnaire was filled, and weight and height were measured.

DISCUSSIONS AND CONCLUSIONS

The body mass index (BMI) was calculated and adjusted for age and sex. Prevalences of overweight and obesity were 17.9 and 7.1%, respectively. BMI increased with age, and it was higher in those who had lower levels of physical activity. Age at menarche was negatively associated with BMI. There was no relationship between macro- and micronutrient intake and overweight and obesity. This study highlights the high prevalence of overweight and obesity in adolescent children in Tehran.

Physiological matrix metalloproteinase concentrations in serum during childhood and adolescence, using Luminex Multiplex technology

Matrix metalloproteinases are a family of zinc-dependent proteinases which are involved in the breakdown and remodeling of extracellular matrix. As children grow and adolescents reach pubescence, their bodies undergo changes that require age-related morphogenesis of the extracellular matrix, possibly requiring unique patterns of matrix metalloproteinase (MMP) expression during periods of rapid tissue growth (i.e., childhood) or accelerated tissue remodeling and expansion (i.e., adolescence). Therefore, we have characterized age-specific and gender-specific differences in circulating concentrations of MMPs (specifically MMP-1, -2, -3, -8 and -9) in 189 serum samples obtained from healthy subjects, aged 2-18 years. MMP concentrations were measured using Fluorokine MultiAnalyte Profiling kits and a Luminex Bioanalyzer, as well as by commercial ELISA. Serum levels of MMP-1, -2, -3, -8, and -9 in healthy pediatric subjects represent log-normal distributions. MMP-2 was significantly negatively correlated with age (r=-0.29; p<0.001), while MMP-3 was significantly positively correlated with age (r=0.38; p<0.001). Although plasma, not serum, is considered the appropriate blood sample for measurement of MMP-8 and -9, serum levels of MMP-8 and -9 were also found to be highly positively correlated with each other (r=0.76; p<0.01). MMP results obtained by Fluorokin MultiAnalyte Profiling methods correlated well with conventional ELISA methods and use of this technology provided several advantages over ELISA.

Altered breast development in young girls from an agricultural environment

In several human populations, the age at which female breast development begins is reported to have declined over the last five decades. Much debate has occurred over whether this reported decline has actually occurred and what factors contribute to it. However, geographical patterns reflecting earlier developmental onset in some human populations suggest environmental factors influence this phenomenon. These factors include interactions between genetic makeup, nutrition, and possible cumulative exposure to estrogens, both endogenous as well as environmental beginning during in utero development. We examined the onset of breast development in a group of peripubertal girls from the Yaqui Valley of Sonora, Mexico. We observed that girls from valley towns, areas using modern agricultural practices, exhibited larger breast fields than those of girls living in the foothills who exhibited similar stature [e.g., weight, height, body mass index (BMI)], and genetic background. Further, girls from valley towns displayed a poorly defined relationship between breast size and mammary gland development, whereas girls from the Yaqui foothills, where traditional ranching occurs, show a robust positive relationship between breast size and mammary size. The differences noted were obtained by a medically based exam involving morphometric analysis and palpation of tissues, in contrast to visual staging alone. In fact, use of the Tanner scale, involving visual staging of breast development for puberty, detected no differences between the study populations. Mammary tissue, determined by palpation, was absent in 18.5% of the girls living in agricultural areas, although palpable breast adipose tissue was present. No relationship was seen between mammary diameter and weight or BMI in either population. These data suggest that future in-depth studies examining mammary tissue growth and fat deposition in breast tissue are required if we are to understand environmental influences on these phenomena.

Serum DDT, age at menarche, and abnormal menstrual cycle length

BACKGROUND

Although dichlorodiphenyl trichloroethane (DDT) exposure is known to affect human endocrine function, few previous studies have investigated the effects of DDT exposure on age at menarche or menstrual cycle length.

METHODS

A cross sectional study was conducted to study the effects of DDT exposure on age at menarche and menstrual cycle length among 466 newly married, nulliparous female Chinese textile workers aged 20-34 years enrolled between 1996 and 1998. Serum was analysed for DDT and its major metabolites. Multivariate linear regression was used to estimate DDT exposure effects on age at menarche and multivariate logistic regression was used to estimate DDT exposure effects on odds of experiencing short or long cycles.

RESULTS

Relative to those in the lowest DDT quartile, the adjusted mean age at menarche was younger in those in the fourth quartile (-1.11 years). Modeled as a continuous variable, a 10 ng/g increase in serum DDT concentration was associated with an adjusted reduction in age at menarche of 0.20 years. Relative to those in the lowest DDT quartile, odds of any short cycle (<21 days) in the previous year were higher for those in the fourth quartile (odds ratio = 2.78; 95% CI 1.07 to 7.14). There were no associations between serum DDT concentrations and odds of experiencing a long cycle (>40 days).

CONCLUSION

Results suggest that DDT exposure was associated with earlier age at menarche and increased risk of experiencing a shortened menstrual cycle.

Individual Differences in Puberty Onset in Girls: Bayesian Estimation of Heritabilities and Genetic Correlations

: We report heritabilities for individual differences in female pubertal development at the age of 12. Tanner data on breast and pubic hair development in girls and data on menarche were obtained from a total of 184 pairs of monozygotic and dizygotic twins. Genetic correlations were estimated to determine to what extent the same genes are involved in different aspects of physical development in puberty. A Bayesian estimation approach was taken, using Markov-chain Monte Carlo simulation to estimate model parameters. All three phenotypes were to a significant extent heritable and showed high genetic correlations, suggesting that a common set of genes is involved in the timing of puberty in general. However, gonadarche (menarche and breast development) and adrenarche (pubic hair) are affected by different environmental factors, which does not support the three phenotypes to be regarded as indicators of a unitary physiological factor.

Family composition and menarcheal age: Anti-inbreeding strategies

Family composition (e.g., the absence of a father) is associated with pubertal timing in women, although the socioendocrinology of the human primate is poorly understood. To better understand social influences on sexual maturation, retrospective data were collected on menarcheal age and family composition from a sample of approximately 1,938 participants from a college population. Absence of a biological father, the presence of half- and step-brothers, and living in an urban environment were associated with earlier menarche. The presence of sisters in the household while growing up, especially older sisters, was associated with delayed menarche. Menarcheal age was not affected by number of brothers in the household, nor was there an effect of birth order. Body weight and race were also associated with menarche. The present findings advance the literature as they are suggestive of putative human pheromones that modulate sexual maturation to promote gene survival and prevent inbreeding, as occurs in rodents and nonhuman primates.

Age at menarche and adult BMI in the Aberdeen children of the 1950s cohort study

BACKGROUND

Few studies have examined whether the inverse association of age at menarche with adult body mass index (BMI) is due to the tendency of BMI to track between childhood and adult life, with childhood BMI playing a causal role in determining age at menarche.

OBJECTIVE

The objective was to investigate whether the association of younger age at menarche with a high BMI and increased likelihood of obesity in middle age is due to confounding with early childhood BMI.

DESIGN

In a historical cohort of 3743 Scottish females born between 1950 and 1955, height and weight were measured in early childhood, and age at menarche and height and weight in middle age were obtained by questionnaire.

RESULTS

The age-adjusted change in mean adult BMI per additional year of age at menarche was -0.64 (95% CI: -0.78, -0.50). Adjustment for childhood BMI measured between 4 and 6 y reduced this value to -0.57 (-0.71, -0.43). Adjustment for childhood and adult social class, parity, smoking, and alcohol intake had little effect. The odds ratio for being obese compared with not being obese in adulthood was 0.82 (0.76, 0.86) per 1-y increase in age at menarche and was unchanged by adjustment for childhood BMI and other covariates.

CONCLUSIONS

The inverse association of age at menarche with BMI and obesity in middle age is not explained by confounding by early childhood BMI. Instead, age at menarche may simply be a proxy marker for the pace of sexual maturation, which itself leads to differences in adiposity (and BMI) in the peripubertal period that track into adult life.

Effects of obesity on growth and puberty

Nutrition is an important regulator of the tempo of human growth. Infancy may represent a critical "window" where variations in nutrition have longer-term consequences for growth and development. Rapid weight gain during infancy is associated with accelerated growth and early pubertal development. Rapid weight gain in infancy is also associated with the development of insulin resistance and an exaggerated adrenarche. Such circulating hormonal changes, together with elevated leptin levels and integral effects of fat cells on hormone action through local 11beta-steroid dehydrogenase and aromatase activity could effect rate of progression of pubertal development in obese subjects. The secular trends in growth and maturation are partly attributed to changing nutrition. Recent data suggest that age at menarche may be static, but there is a debate as to whether the first signs of puberty are being seen much earlier in obese girls. Rapid early weight gain, obesity and early development may have implications for later health through the development of PCOS and overall association with cancer risk.