Timing of pubertal growth and menarche in indigenous Qom girls of Argentina

Longitudinal analysis of cortisol changes during pubertal development in indigenous Qom girls

Pubertal research has primarily focused on hypothalamic-pituitary-gonadal axis (HPG) regulation of puberty, though the hypothalamic-pituitary-adrenal axis (HPA) is increasingly considered critical. Heightened HPA function proxied by increasing cortisol levels may play a role in accelerated pubertal timing. However, the extent to which cortisol varies across ages and its relation to pubertal changes in linear growth are less well substantiated. We explored relationships between age, linear growth, adiposity, C-peptide (proxy for insulin), and cortisol across puberty, and we tested whether higher cortisol levels are associated with earlier ages at menarche and peak height velocity. We utilize longitudinal data (n = 777 urine samples) from Qom females ages 7-14 (n = 46) and test our pre-registered analysis using Bayesian longitudinal mixed effects models and joint modeling techniques. We find limited evidence supporting the overarching hypothesis that HPA upregulation is associated with pubertal maturation or timing. We find some evidence that HPA upregulation, as proxied by cortisol, may be more clearly related to differences in relative linear growth at early-mid puberty, as measured by height-for-age z-scores. Transdisciplinary perspectives on puberty, including the assumption that stressors acting via cortisol accelerate pubertal development, are discussed.

Nutritional status and age at menarche in Amazonian students

OBJECTIVES

Age at menarche (MA) is a proxy for biological maturation and a parameter of socioeconomic changes. Worldwide, anticipation of menarche is associated with nutritional transition and excess weight. The objective of this study was to evaluate the MA in Amazonian students and its association with nutritional status, ethnicity, and socioeconomic level.

METHODS

Cross-sectional study with 1,017 students aged 6 to 17 living in the city of Manaus, Brazil. MA was analyzed by status quo and recall; its association with body mass index (BMI), race, socioeconomic status, and adult height was examined.

RESULTS

559 (51.9%) participants had already experienced menarche. In 91.7%, menarche occurred between 10 and 14 years of age; the mean age at the onset of menarche was 11.9 years. Overweight (11.6 years) and obese (11.4 years) participants reached menarche earlier than those with normal weight (12 years) and lean (12.7 years) participants. The associations between MA and nutritional status showed that overweight and obesity are risk factors for the early occurrence of menarche. MA was not associated with socioeconomic status/parental education or race. However, excess weight was associated with earlier MA in all races and social classes. The adult height was slightly lower in girls with menarche before 12 years old (157.9 vs 159.4 cm).

CONCLUSION

Regardless of socioeconomic level or ethnicity, excess weight was associated with earlier menarche in Amazonian students.

Sexual minority status is associated with earlier recalled age of menarche: Evidence from the 2005-2016 National Health and Nutrition Examination Survey

INTRODUCTION

Menarcheal timing is associated with growth, development, health, wellbeing, and reproduction across the lifespan. Although sexual orientation is a known correlate of health and developmental inequities, relatively little evolutionarily framed research has investigated sexual orientation-based variation in maturational timing. To improve our understanding of menarcheal timing among sexual minority (SM) people, we use a biocultural-evolutionary life history lens that takes into account the stresses of minoritization to examine the relationship between sexual orientation and self-reported age at menarche in a sample of American adults.

METHODS

Using the U.S. National Health and Nutrition Examination Survey (NHANES), a large, nationally representative dataset (n = 9757), we fit multiple logistic regression models and survival curves to evaluate associations between sexual orientation, indicators of somatic and material resources during adolescence (e.g., education, citizenship, upper arm length), and self-reported menarche.

RESULTS

SM respondents were more likely to report earlier (by 4-5 months) ages of menarche (p < .001). Post-hoc tests revealed that these differences were driven by bisexual (p < .001) and same-sex experienced (p < .001) relative to heterosexual and lesbian/gay respondents. Earlier menarcheal timing among SM respondents persisted after adjusting for socio-demographic factors and proxies of developmental conditions.

DISCUSSION

Our findings reveal that SM status is associated with earlier ages of menarche, an important social and reproductive milestone. We argue that uniting life history theory with the minority stress hypothesis better explains differences in menarcheal timing by sexual orientation than previous paradigms. Investigators should attend to sexual orientation-based variation in maturational timing using holistic, inclusive approaches.

GENETICS IN ENDOCRINOLOGY: Genetic etiologies of central precocious puberty and the role of imprinted genes

Pubertal timing is regulated by the complex interplay of genetic, environmental, nutritional and epigenetic factors. Criteria for determining normal pubertal timing, and thus the definition of precocious puberty, have evolved based on published population studies. The significance of the genetic influence on pubertal timing is supported by familial pubertal timing and twin studies. In contrast to the many monogenic causes associated with hypogonadotropic hypogonadism, only four monogenic causes of central precocious puberty (CPP) have been described. Loss-of-function mutations in Makorin Ring Finger Protein 3(MKRN3), a maternally imprinted gene on chromosome 15 within the Prader-Willi syndrome locus, are the most common identified genetic cause of CPP. More recently, several mutations in a second maternally imprinted gene, Delta-like noncanonical Notch ligand 1 (DLK1), have also been associated with CPP. Polymorphisms in both genes have also been associated with the age of menarche in genome-wide association studies. Mutations in the genes encoding kisspeptin (KISS1) and its receptor (KISS1R), potent activators of GnRH secretion, have also been described in association with CPP, but remain rare monogenic causes. CPP has both short- and long-term health implications for children, highlighting the importance of understanding the mechanisms contributing to early puberty. Additionally, given the role of mutations in the imprinted genes MKRN3 and DLK1 in pubertal timing, other imprinted candidate genes should be considered for a role in puberty initiation.

Adolescent growth and BMI and their associations with early childhood growth in an urban South African cohort

OBJECTIVES

The timing and magnitude of adolescent growth may be influenced by ethnicity and early life factors. We aimed to (a) characterize ethnic differences in the magnitude, timing, and intensity of adolescent growth in height, weight, and BMI; (b) assess the effect of early childhood growth on adolescent growth in black children.

METHODS

Data were from the Birth to Twenty Plus cohort (Bt20+) in Johannesburg, South Africa (n = 3273). Height, weight, and BMI were modeled with ethnic comparisons using the SuperImposition by Translation and Rotation for 2089 participants who had data from 7 to 23 years. Relative weight gain and relative linear growth between 0 and 24 months and 24 and 60 months were generated. Multiple regression analyses were used to assess associations between childhood and adolescent growth.

RESULTS

White children were 5 cm (SE: 0.7) taller than black children through adolescence. Black boys had a later timing of adolescent height (0.65 years ±0.12) than white boys, which in black girls was 0.24 years (0.11) earlier than in white girls. Black girls had faster BMI velocity than white girls. Among black children, birth weight and both relative weight gain 0 to 24 and relative linear growth between 3 and 24 months and 24 and 60 months were positively associated with the magnitude of adolescent growth and negatively associated with timing.

CONCLUSION

Sex dimorphism in ethnic differences in timing of adolescent height growth may reflect some yet unexplained drivers for rapid weight gain and obesity in black females but not black males. Rapid weight gain in early life may contribute to faster adiposity accrual in adolescence.

Estimating peak height velocity in individuals: a comparison of statistical methods

BACKGROUND

Estimates pertaining to the timing of the adolescent growth spurt (e.g. peak height velocity; PHV), including age at peak height velocity (aPHV), play a critical role in the diagnosis, treatment, and management of skeletal growth and/or developmental disorders. Yet, distinct statistical methodologies often result in large estimate discrepancies.

AIM

The aim of the present study was to assess the advantages and disadvantages of three modelling methodologies for height as well as to determine how estimates derived from these methodologies may differ, particularly those that may be useful in paediatric clinical practice.

SUBJECTS AND METHODS

Height data from 686 individuals of the Fels Longitudinal Study were modelled using 5th order polynomials, natural cubic splines, and SuperImposition by Translation and Rotation (SITAR) to determine aPHV and PHV for all individuals together (i.e. population average) by sex and separately for each individual. Estimates within and between methodologies were calculated and compared.

RESULTS

In general, mean aPHV was earlier, and PHV was greater for individuals when compared to estimates from population average models. Significant differences between mean aPHV and PHV for individuals were observed in all three methodologies, with SITAR exhibiting the latest aPHV and largest PHV estimates.

CONCLUSION

Each statistical methodology has a number of advantages when used for specific purposes. For modelling growth in individuals, as one would in paediatric clinical practice, we recommend the use of the 5th order polynomial methodology due to its parameter flexibility.

The levelling-off of the secular trend of age at menarche among Italian girls

OBJECTIVE

The main aim of this study was to verify whether the secular trend stopped in Italy by comparing the results of a 1990-2000 birth cohort versus a 1980-1990 birth cohort of Italian young women. The results were used to speculate about age at menarche as adaptive response to non-genetic factors.

METHODS

In 2016, a study was set on 413, 18-to-26 year-old women (1990-2000 birth cohort) attending two Italian Universities by web-based, self-reported questionnaires. Previously in 2000, a research including 3,783 high school female students (1980-1990 birth cohort) was led. The age at menarche distribution was performed by Kaplan-Meier analysis. The comparison between the findings of the two birth cohorts was performed by Wilcoxon sum-rank test. Mixed models analysis was applied to evaluate the effect of cohort and socio-economic status on age at menarche.

RESULTS

1990-2000 cohort's age at menarche median was 12.44y (95%CI 12.37; 12.59y). There was no significant difference with age at menarche of the previous cohort (p = 0.56). Consistently, the advance of age at menarche in comparison to the mothers' one was not significantly different between the two cohorts (-0.27y±0.10y vs -0.25y±0.03y, p = 0.33). The socio-economic level was not significantly associated with menarcheal age.

CONCLUSIONS

The findings of this study confirm that, like in other developed countries, the advance of age at menarche has stopped in Italy, consistently with the stop of the improvement of socio-economic conditions. Further studies are needed to explore the differential effect of each non-genetic factor to outline future scenarios of human sexual maturation.

TRIAL REGISTRATION

the Comitato Etico per la Sperimentazione Clinica (CESC) della Provincia di Padova of the Veneto Region (Italy), n°3993/U16/16.

Adolescence as a Biocultural Life History Transition

While the categories of adolescence and puberty are often treated as one, the existence of two distinct terms points to different kinds of maturation in humans. Puberty refers to a period of coordinated somatic growth and reproductive maturation that shifts individuals from nonreproductive juvenility to reproductive maturity. Adolescence includes the behavioral and social assumption of adult roles. Life history theory offers powerful tools for understanding why puberty occurs later in humans than in other primates, including the benefits of delayed reproduction as part of a cooperation-intensive life history strategy. It also sheds light on the ways that pubertal timing responds to environmental variation. I review the mechanisms of maturation in humans and propose biocultural approaches to integrate life historical understandings of puberty with a broader definition of environment to encompass the concept of adolescence.

Birth mode and infectious morbidity risks in Qom children of Argentina

OBJECTIVES

Cesarean delivery may increase childhood infectious morbidity risks via altered birth exposures and subsequent immune, microbial, and epigenetic development. Many Latin American indigenous populations experience dual burdens of infectious and chronic diseases, and are particularly vulnerable to rising rates of cesarean delivery and associated adverse outcomes. The Qom/Toba are an indigenous population in Argentina experiencing rapid lifestyle transitions. We hypothesized that cesarean delivery would be associated with increased risk of infectious symptoms in Qom children after adjusting for gestational and nutritional factors.

METHODS

We conducted a secondary analysis of birth records and monthly anthropometric and illness data collected previously from 90 Qom children (aged 1-55 months). We tested for additive effects of birth mode on risk of gastrointestinal (GI) and respiratory illness (RI) in mixed-effects logistic regression models adjusting for child weight-for-age (WAZ), weaning, and gestational and maternal age.

RESULTS

Cesarean deliveries accounted for 46% of births and were associated with maternal age < 20 and ≥ 30 years, gestational age < 39 weeks, and prenatal complications. GI and RI risks were reduced in association with cesarean delivery, greater WAZ, weaning, maternal age ≥ 30 years, and gestational age < 39 weeks.

CONCLUSIONS

The relationship between cesarean delivery and reduced infectious risks may reflect statistical confounding with relatively rapid postnatal growth and greater adiposity. Postnatal growth trajectories may be important mediators of long-term morbidity risks associated with cesarean delivery. The frequency of cesarean deliveries among the Qom remains concerning given traditionally high rates of fertility and adolescent pregnancy.