Timing In Girls Research Articles

Concurrent and longitudinal associations of peers’ acceptance with emotion and effortful control in kindergarten

The purpose of the study was to evaluate bidirectional associations between peer acceptance and both emotion and effortful control during kindergarten (N = 301). In both the fall and spring semesters, we obtained peer nominations of acceptance, measures of positive and negative emotion based on naturalistic observations in school (i.e., classroom, lunch/recess), and observers’ reports of effortful control (i.e., inhibitory control, attention focusing) and emotions (i.e., positive, negative). In structural equation panel models, peer acceptance in fall predicted higher effortful control in spring. Effortful control in fall did not predict peer acceptance in spring. Negative emotion predicted lower peer acceptance across time for girls but not for boys. Peer acceptance did not predict negative or positive emotion over time. In addition, we tested interactions between positive or negative emotion and effortful control predicting peer acceptance. Positive emotion predicted higher peer acceptance for children low in effortful control.

Parental involvement, child effort, and the development of immigrant boys' and girls' reading and mathematics skills: A latent difference score growth model

Gender differences in elementary school performance among immigrant children have not yet been well documented. This study examined how differences in parental involvement, child effort, and family characteristics and resources contribute to immigrant boys'-and girls' academic achievement from kindergarten through 5th-grade. The sample was drawn from the Early Childhood Longitudinal Study-Kindergarten cohort. Using a latent score growth model, this study found that parents' involvement at home benefited boys' reading and mathematics skills throughout all early elementary school years, but did not have the same benefit for girls. For both boys and girls, child effort in reading appears to be strongly linked to better reading and mathematics skills at kindergarten and to subsequent improvement between grades. The positive associations of parental involvement and child's effort with test scores were greater during earlier years than during later years for boys, whereas there was no difference in the association over time for girls.

Children’s Participation in Organized Sport and Physical Activities and Active Free Play: Exploring the Impact of Time, Gender and Neighbourhood Household Income Using Longitudinal Data

This study examines the associations among socioeconomic status (SES), aging, gender and sport and physical activity participation from late childhood into adolescence. Drawing from previous research, we test three hypotheses regarding the impact of aging on SES and sport participation using longitudinal data. The data come from a prospective cohort study of children, all of whom were enrolled in grade 4 (at baseline) in the public school system of a large region of southern Ontario, Canada. We examine two outcome measures: participation in organized sport and physical activity and active free play. Our results show different effects of neighborhood household income, aging and gender for each outcome. For organized sport participation, neighborhood household income effects are constant over time for both boys and girls. For active free play however, neighborhood household income differences widen (or diverge) over time for girls, but not for boys. We discuss the implications of these findings for future research and policy considerations.Cette étude examine les associations entre statut socioéconomique, âge, genre et participation en sport et en activité physique de la fin de l’enfance à l’adolescence. Nous nous appuyons sur les recherches antérieures et des données longitudinales pour tester trois hypothèses à propos de l’impact de l’âge sur le statut socioéconomique et la participation en sport. Les données proviennent d’une étude de cohorte prospective d’enfants, tous étant inscrits en 4ème année (au début de l’étude) dans le système scolaire public d’une grande région du sud de l’Ontario au Canada. Nous mesurons deux types de résultats : la participation en sport organisé et activité physique et le jeu libre actif. Nos résultats montrent différents effets du revenu du ménage du quartier, de l’âge et du genre pour chaque résultat. Pour la participation en sport organisé, les effets du revenu du ménage du quartier sont constants avec le temps à la fois pour les garçons et les filles. Pour le jeu libre actif en revanche, les différences dans le revenu du ménage augmentent (ou divergent) avec le temps pour les filles, mais pas pour les garçons. Nous discutons les implications de ces résultats pour les études et politiques futures.

Understanding the Link Between Pubertal Timing in Girls and the Development of Depressive Symptoms: The Role of Sexual Harassment.

The link between sexual maturation, or pubertal timing, in girls and adolescent depressive symptoms is well-documented, but the underlying processes remain unclear. We examined whether sexual harassment, which has previously been linked to both pubertal timing and depressive symptoms, mediates this link, using a two-wave longitudinal study including 454 girls in 7th (M age =13.42, SD=.53) and 8th grade (M age =14.42, SD=.55). Pubertal timing was linked to depressive symptoms in both age groups, and predicted an increase in depressive symptoms among the 7th graders. Sexual harassment significantly mediated the link between pubertal timing and depressive symptoms among the 7th, but not the 8th grade girls. Together, our findings suggest that one way to prevent depressive symptoms among early-maturing girls could be to address sexual harassment in preventive intervention in early adolescence.

Associations Between Home Environment and After-School Physical Activity and Sedentary Time Among 6th Grade Children.

This study examined associations of various elements of the home environment with after-school physical activity and sedentary time in 671 6th-grade children (Mage = 11.49 ± 0.5 years). Children's after-school total physical activity, moderate-to-vigorous physical activity, and sedentary time were measured by accelerometry. Parents completed surveys assessing elements of the home social and physical environment. Mixed-model regression analyses were used to examine the associations between each element of the home environment and children's after-school physical activity and sedentary time. Availability of home physical activity resources was associated positively with after-school total physical activity and negatively with after-school sedentary time in boys. Parental support was associated positively with after-school total physical activity and MVPA and negatively with after-school sedentary time in girls. The home physical environment was associated with boys' after-school physical activity and sedentary time, whereas the home social environment was associated with girls' after-school physical activity and sedentary time.

Are CYP1A1, CYP17 and CYP1B1 mutation genes involved on girls with precocious puberty? A pilot study

ObjectivesTo investigate three genes associated with puberty timing in girls with central precocious puberty by evaluating the association between polymorphism in the gene sequence codifying the enzymes participating in steroidogenesis, CYP1A1, CYP17, and CYP1B1 and central precocious puberty. Study designA total of 177 patients was included and divided into two groups: Case group with 73 girls diagnosed with central precocious puberty; Control group with 104 girls with puberty onset after 8 years of age who were followed at the Sector of Gynecology of Childhood and Adolescence, Division of Gynecology Clinic, HC-FMUSP. Polymorphism presence was assessed in the genes involved in estrogen metabolism (CYP1A1, CYP17, and CYP1B1) by the restriction fragment length polymorphism (RFLP) technique using DNA from peripheral blood. ResultsNo significant difference in the distribution of the CYP1A1 Mspl (p=0.86) and CYP17 (p=0.12) genotypes was detected between the two study groups. As for CYP1B1 Eco571, the mutated C/C genotype was found to be more frequent in the control group than in the case group (p=0.03). ConclusionOur data suggest the CYP1B1 Eco571 gene variant is associated with puberty timing.

Moderating effect of gender on the prospective relation of physical activity with psychosocial outcomes and asthma control in adolescents: a longitudinal study

Objective: Adolescents with asthma experience more psychosocial and physiological problems compared to their healthy peers. Physical activity (PA) might decrease these problems. This study was the first observational longitudinal study to examine whether habitual PA could predict changes in psychosocial outcomes (i.e. symptoms of anxiety and depression, quality of life [QOL] and stress) and asthma control over time in adolescents with asthma and whether gender moderated these relationships. Methods: Adolescents with asthma (N = 253; aged 10–14 years at baseline) were visited at home in the spring/summer of 2012 and 2013. They completed questionnaires assessing their habitual PA, symptoms of anxiety and depression, QOL, perceived stress and asthma control. Path analyses using Mplus were conducted to examine longitudinal relationships among habitual PA, psychosocial outcomes and asthma control (controlled for body mass index, age and gender). Using multi-group analyses, we examined whether gender moderated these relationships. Results: Path analyses in the total group showed that habitual PA did not predict changes in psychosocial outcomes or asthma control over time. Multi-group analyses showed that gender moderated the relation of habitual PA with anxiety and depression. Habitual PA only significantly predicted a decrease in anxiety and depression over time for girls but not for boys. Conclusions: Increasing habitual PA in girls with asthma might decrease their symptoms of anxiety and depression.

Peculiarities of heart rate variability in children with gastroesophageal reflux disease

Introduction. According to modern literature gastroesophageal reflux disease (GERD) is multifactorial illness. One of the most important risk factors for this disease is considered a violation of autonomic nervous system balance. The study of heart rate variability (HRV) in recent times is used as the most informative noninvasive method for quantitative assessment of autonomic regulation of heart rate.The aim of research. Determining the characteristics of autonomic regulation in children with gastroesophageal reflux disease.Materials and methods. The study involved 77 children with chronic gastroduodenal pathology (aged 9 to 17 years). The main group consisted of 54 children with GERD (Group 1 - 46 children with GERD with esophagitis, Group 2 - GERD without esophagitis), comparison group comprised 23 children without clinical and endoscopic manifestations of the esophagus pathology. The following methods were conducted: clinical and medical history, fibroesofagogastroduodenoscopy, intragastric pH-metry, pH monitoring in the esophagus, Holter cardiac monitoring, variational statistics, correlation analysis.Results. 34.8% of children with GERD with esophagitis had sympathicotonia (p<0.05), 43.5% - vagotonia and 21.7% - eytoniya (p<0,05). In 29.0% of children with GERD without esophagitis sympathicotonia was registered and the same number - vagotonia, eytoniya - in 42.0%. During the diurnal cycle predominance of sympathetic activity in children with GERD is observed, more girls with esophagitis and the presence of UCTD (undifferentiated connective tissue dysplasia) symptoms. Girls with esophagitis had lower time analysis indices of HRV at day time relative to boys of the same group. The predominance of sympathetic activity in girls confirmed by significantly lower rates of pNN50 (p<0.05). Tension-time index at day time was significantly higher in girls with esophagitis than in boys, which also indicated the predominancy of sympathetic tone (74,4 ± 34,6 vs conv 34,2 ± 14,1, p<0, 05). At night time in girls of group 1 values of HRV were significantly lower relative to boys (p <0.05. The stress index was significantly higher at night in girls with esophagitis (53,9 ± 33,7 vs conv 15,9 ± 8,6 cu in boys, p<0.05).For children with esophagitis with symptoms of UCTD increased activity of the sympathetic (autonomic nervous system) ANS level is characteristic. If children without UCTD SDNNi values were within 82,5 ± 12,6 ms and 94,1 ± 20,7 ms, respectively at day and at night time, than in the presence of UCTD manifestations these figures were reduced by 1.4-fold (p<0.05). Similar changes were characteristic for rMSSD and pNN50. SI analysis showed significant stress adaptation capabilities in children with esophagitis associated with UCTD.Children with acid reflux indicators of reflecting parasympathetic activity, were almost 1.5 times lower than in children with alkaline GER (gastroesophageal reflux), but did not differ significantly from that of children with mixed GER. Thus, in children with acid GER indexes of SDNNi and rMSSD were within 62,2 ± 12,6 ms (p<0.05) and 38,4 ± 13,2 ms (p<0.05) at day time 72 9 ± 20,9 ms (p <0.05) and 56,9 ± 19,9 ms (p <0.05) at night time respectively, relative to children with alkaline GER (SDNNi amounted to 90,9 ± 32,6 ms and rMSSD - 64,0 ± 32,2 ms at day time and SDNNi - 101,6 ± 27,7 ms and rMSSD - 91,8 ± 39,2 ms at night time). Distinction of children with acid GER was significantly lower CI (circadian index) indicators, that is indicating exhaustion of adaptive reserves in these children.Was established negative correlation of medium strength between the number GER lasting more than 5 minutes and the time performance analysis of HRV (at day time r = -0,57; p <0.05; at night time r = -0,56; p <0.05). The more stress of sympathetic division of ANS, the bigger number of long-term GER.Conclusion. Thus, according to the analysis of HRV in children with GERD derangements of rhythmicity and intensity of fluctuations of the sympathetic and parasympathetic parts of the ANS identify. It was noted that the prevailing of sympathetic link of ANS is more typical for girls and in the presence of UCTD symptoms.

Genome-wide association study of sexual maturation in males and females highlights a role for body mass and menarche loci in male puberty.

Little is known about genes regulating male puberty. Further, while many identified pubertal timing variants associate with age at menarche, a late manifestation of puberty, and body mass, little is known about these variants' relationship to pubertal initiation or tempo. To address these questions, we performed genome-wide association meta-analysis in over 11 000 European samples with data on early pubertal traits, male genital and female breast development, measured by the Tanner scale. We report the first genome-wide significant locus for male sexual development upstream of myocardin-like 2 (MKL2) (P = 8.9 × 10(-9)), a menarche locus tagging a developmental pathway linking earlier puberty with reduced pubertal growth (P = 4.6 × 10(-5)) and short adult stature (p = 7.5 × 10(-6)) in both males and females. Furthermore, our results indicate that a proportion of menarche loci are important for pubertal initiation in both sexes. Consistent with epidemiological correlations between increased prepubertal body mass and earlier pubertal timing in girls, body mass index (BMI)-increasing alleles correlated with earlier breast development. In boys, some BMI-increasing alleles associated with earlier, and others with delayed, sexual development; these genetic results mimic the controversy in epidemiological studies, some of which show opposing correlations between prepubertal BMI and male puberty. Our results contribute to our understanding of the pubertal initiation program in both sexes and indicate that although mechanisms regulating pubertal onset in males and females may largely be shared, the relationship between body mass and pubertal timing in boys may be complex and requires further genetic studies.

Trends in television time, non-gaming PC use and moderate-to-vigorous physical activity among German adolescents 2002-2010.

BackgroundStudies in youth highlight that moderate-to-vigorous physical activity (MVPA) and screen-time behaviours such as television viewing and PC use are associated with a range of health outcomes. However, little is known about recent trends in these behaviours in adolescents. This paper presents time trends in German adolescents’ television time, non-gaming PC use as well as MVPA from 2002 to 2010.MethodsData were derived from the cross-sectional German Health Behaviour in School-aged Children (HBSC) study in 2002, 2006 and 2010. Analyses were based on 16,918 11-to 15-year olds boys (49.1%) and girls. Outcome variables were time spent in TV viewing and using a PC (weekday and weekend day) as well as the number of days achieving 60 minutes of MVPA. Changes in both screen-time behaviours and MVPA over time were analysed using sex-specific linear regression, controlling for age and family affluence.ResultsTV viewing on weekdays, but not at weekends, declined steadily over time with a difference between 2002 and 2010 of 12.4 min/day in girls and 18.3 min/day in boys (p for trend < .01). We found a strong increase in PC use for non-gaming purposes over time for girls only, with a difference between 2002 and 2010 of 54.1 min/weekday and 68.8 min/weekend day (p < .001). For MVPA we found a slight statistically significant increase in terms of meeting PA guidelines as well as days/week in MVPA for boys and girls (p < .001). In 2010 14.0% of girls and 19.9% of boys met PA guideline.ConclusionAlthough MVPA increased from 2002 to 2010 in German adolescents, the time spent in MVPA was still low. Despite the observed decrease in TV viewing, there was no overall decline in the observed screen-based behaviours, especially for girls. This is mainly due to a marked increase in use of a PC for chatting on-line, internet, emailing, homework etc. among girls during the last ten years which outweighs the corresponding decrease in TV viewing. The findings highlight a need for strategies and interventions aimed at reducing screen-time behaviours and promoting MVPA.

The longitudinal interplay of affective and cognitive empathy within and between adolescents and mothers.

This 4-year study examined longitudinal interplays between adolescents' and mothers' self-reported empathic concern (EC) and perspective taking (PT). We investigated (a) whether adolescents' EC predicted rank-order change in their PT over time, or vice versa; (b) whether mothers' empathy predicted relative increases in adolescents' empathy; (c) whether adolescent gender moderated the over-time links from mothers' to adolescents' empathy; and (d) whether the rank-order stability of EC and PT over time differed within and between respondents. Adolescents' EC positively predicted their PT over time, but not vice versa. Mothers' PT positively predicted adolescent PT over time for girls, but not for boys. The rank-order stability of adolescents' EC was greater than their PT. Maternal PT and EC were equally stable and were more stable than in adolescents. This study contributes the first empirical evidence that the developmental order of adolescents' empathy runs from affective to cognitive empathy, in contrast to prior theoretical and experimental literature that has emphasized the reverse direction. It further provides the 1st longitudinal evidence of intergenerational empathy transmission. These findings support the notion that adolescence is a developmentally sensitive period for PT.

Prenatal Lead Exposure and Puberty Timing in Girls

To the Editor: Findings from cross-sectional epidemiologic studies suggest that blood lead concentrations predict later development of secondary sexual characteristics and reproductive maturation in adolescent girls.1–6 Evidence on the role of prenatal lead exposure on puberty timing is lacking. We examined data from mother-daughter pairs enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) to determine this association. Whole blood samples were collected from pregnant mothers at enrollment (1991–1992) and analyzed for lead content using inductively coupled plasma mass spectrometry. The median gestational age of blood collection was 11 weeks. Repeated assessments of pubertal status were obtained from daughters, beginning at age 8 and continuing through age 17. Participants were asked to examine line drawings and descriptions of the five Tanner stages for breast size and pubic hair and to record which drawing most closely resembled their own stage of development. At each assessment, participants were asked whether their first menstrual period had occurred and when it had occurred.7 We restricted our analyses to singleton white daughters. The following covariates were selected a priori and included in all adjusted analyses: maternal smoking during pregnancy, maternal education, previous births, and daughters’ height at age 7. Data collection instruments and methods have been described elsewhere (www.bristol.ac.uk/alspac). We used parametric survival models to obtain the median age and cumulative probabilities of attainment of pubertal markers to describe unadjusted patterns in pubertal markers over time, assuming a Normal distribution. Hazards ratios (HRs) and 95% confidence intervals (CIs) were estimated by Cox proportional hazards models, using the group with prenatal lead concentrations <5 µg/dl as the reference. The proportional hazards assumption was assessed for all variables in the models. Time to menarche was based on the age of attainment given by participants or right-censored using the age of the last completed assessment. For Tanner stages, time to event was defined using the midpoint between two assessments. Alternatively, the data were left-censored if the participant reported a stage 2 or greater on their first returned assessment or right-censored if stage 2 was not attained. Human subject protection was assessed and approved by the ALSPAC Law and Ethics Committee, the Local Research Ethics Committees, and the Centers for Disease Control and Prevention Institutional Review Board. Menarche analyses (n = 918) comprised data for the full follow-up period, whereas Tanner stage analyses (n = 765) were based on status up to 14 years of age. The median age at menarche was 150 months (12.5 years), median age at breast stage ≥2 was 130 months (10.8 years), and median age at pubic hair stage ≥2 was 135 months (11.3 years). The median prenatal lead concentration was 3.4 µg/dl (range, 0.8–19.1 µg/dl). Fifteen percent of mothers had lead concentrations ≥5 µg/dl. The median age at menarche in daughters with prenatal concentrations ≥5 µg/dl did not vary from those with lead concentrations <5 µg/dl (both were 150 months). The two groups were also similar regarding breast stage ≥2 (129 vs. 131 months, respectively) and pubic hair stage ≥2 (133 vs. 135 months). Unadjusted survival distributions for age at menarche by exposure category did not vary over time (Figure). Curves for breast and pubic hair attainment showed similar patterns. The rate of attainment of pubertal markers in daughters with prenatal lead concentrations ≥5 µg/dl did not differ from those with lower lead concentrations. Attainment of menarche (adjusted HR = 1.00 [95% CI = 0.82–1.21]), breast stage ≥2 (1.08 [0.87–1.35]), and pubic hair stage ≥2 (1.02 [0.83–1.26]) were all unrelated to prenatal lead concentrations. Our findings are not consistent with those of cross-sectional studies, which have suggested an antiestrogenic effect of lead in adolescent girls.FIGURE: Unadjusted survival distribution for menarche attainment by categories of prenatal lead ≥5 µg/dl and <5 µg/dl.ACKNOWLEDGMENTS We are extremely grateful to all the families who took part in this study, the midwives for their help in recruiting them, and the whole ALSPAC team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists, and nurses. Mildred Maisonet Jouni J. K. Jaakkola Center for Environmental and Respiratory Health Research, University of Oulu, Oulu, Finland, Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland, [email protected] Caroline M. Taylor Centre for Child and Adolescent Health, University of Bristol, Bristol, United Kingdom Michele Marcus Kaiser Permanente Center for Health Research, Atlanta, GA Jean Golding Centre for Child and Adolescent Health, University of Bristol, Bristol, United Kingdoml

Age at menarche and type 2 diabetes risk: the EPIC-InterAct study.

OBJECTIVEYounger age at menarche, a marker of pubertal timing in girls, is associated with higher risk of later type 2 diabetes. We aimed to confirm this association and to examine whether it is explained by adiposity.RESEARCH DESIGN AND METHODSThe prospective European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct case-cohort study consists of 12,403 incident type 2 diabetes cases and a stratified subcohort of 16,154 individuals from 26 research centers across eight European countries. We tested the association between age at menarche and incident type 2 diabetes using Prentice-weighted Cox regression in 15,168 women (n = 5,995 cases). Models were adjusted in a sequential manner for potential confounding and mediating factors, including adult BMI.RESULTSMean menarcheal age ranged from 12.6 to 13.6 years across InterAct countries. Each year later menarche was associated with 0.32 kg/m2 lower adult BMI. Women in the earliest menarche quintile (8–11 years, n = 2,418) had 70% higher incidence of type 2 diabetes compared with those in the middle quintile (13 years, n = 3,634), adjusting for age at recruitment, research center, and a range of lifestyle and reproductive factors (hazard ratio [HR], 1.70; 95% CI, 1.49–1.94; P < 0.001). Adjustment for BMI partially attenuated this association (HR, 1.42; 95% CI, 1.18–1.71; P < 0.001). Later menarche beyond the median age was not protective against type 2 diabetes.CONCLUSIONSWomen with history of early menarche have higher risk of type 2 diabetes in adulthood. Less than half of this association appears to be mediated by higher adult BMI, suggesting that early pubertal development also may directly increase type 2 diabetes risk.

Short-term neonatal/prepubertal exposure of dibutyl phthalate (DBP) advanced pubertal timing and affected hypothalamic kisspeptin/GPR54 expression differently in female rats

Dibutyl phthalate (DBP) had been widely used and its exposure in children has been thought to be one of the reasons causing a trend of advanced pubertal timing in girls. Puberty starts from hypothalamic gonadotropin-releasing hormone release which is controlled by many factors including neurotransmitter kisspeptin and its receptor GPR54. These neural organization or reorganization happens in hypothalamus during neonatal or prepubertal period which may be two target windows of DBP exposure. The present study was designed to determine: (1) the difference between the effects of neonatal and prepubertal DBP exposure on female pubertal timing; (2) whether kisspeptin/GPR54 expression in hypothalamus would respond to neonatal and prepubertal DBP exposure differently. Female Sprague-Dawley rats were exposed by subcutaneous injection of 0.5, 5 and 50mg/kg DBP during Postnatal day (P)1–5 (neonatal) or P26–30 (prepubertal). Physiological data demonstrated that both neonatal and prepubertal DBP exposure could advance pubertal timing significantly accompanied by irregular estrous cycles but only a little gonadal impairment. Exposure-period-related difference was found significant with prepubertal exposure groups having longer estrous cycle duration, heavier at vaginal opening and having higher serum estradiol level compared with neonatal exposure groups. Molecular data showed an up-regulated trend in kisspeptin mRNA and immunoreactivity levels of hypothalamic area arcuate but a down-regulation in GPR54 mRNA expression after P1–5 DBP treatment. In P26–30 groups, kisspeptin mRNA and immunoreactivity levels tended to be lower after DBP treatment. These results demonstrated small dose of DBP could induce earlier pubertal timing in females and both neonatal and prepubertal periods were critical windows for DBP exposure.

Gestational lead concentrations and timing of menarche in girls enrolled in the Avon Longitudinal Study of Parents and Children

Background. Lead is a persistent, toxic substance and its exposure has been associated with later puberty onset and maturity. Current literature on the role of lead on puberty timing of girls is li...

Linking Childhood Maltreatment with Girls' Internalizing Symptoms: Early Puberty as a Tipping Point.

Early pubertal timing in girls is one of the most frequently replicated antecedents of adolescent emotional distress. Yet understanding the impact of pubertal timing in psychosocial development has presented something of a conundrum for developmentalists, as earlier physical maturation may often be preceded by a range of early adversities and life stressors. The present paper disentangles these associations by investigating childhood maltreatment, adolescent internalizing symptoms, and perceived pubertal timing in girls who were residing in foster care at study entry (N = 100, M = 11.54 years old at Time 1). Girls were assessed at two time points two years apart. There were no significant direct effects of maltreatment on internalizing symptoms; rather, childhood sexual abuse predicted earlier perceived pubertal development at study onset which, in turn, was associated with higher levels of internalizing symptomatology. These higher levels of internalizing symptoms persisted over the two years of the study. This distinctive role for early pubertal timing - even within a sample subject to stressors and risks which far exceed the developmental norm - confirms the unique salience of pubertal timing in emotional adjustment, and suggests that the heightened sexual circumstances of puberty may be especially disturbing for girls whose lives have already been traumatically disrupted by inappropriate and unwanted sexual experiences.

Association of Adiposity Genetic Variants With Menarche Timing in 92,105 Women of European Descent

Obesity is of global health concern. There are well-described inverse relationships between female pubertal timing and obesity. Recent genome-wide association studies of age at menarche identified several obesity-related variants. Using data from the ReproGen Consortium, we employed meta-analytical techniques to estimate the associations of 95 a priori and recently identified obesity-related (body mass index (weight (kg)/height (m)(2)), waist circumference, and waist:hip ratio) single-nucleotide polymorphisms (SNPs) with age at menarche in 92,116 women of European descent from 38 studies (1970-2010), in order to estimate associations between genetic variants associated with central or overall adiposity and pubertal timing in girls. Investigators in each study performed a separate analysis of associations between the selected SNPs and age at menarche (ages 9-17 years) using linear regression models and adjusting for birth year, site (as appropriate), and population stratification. Heterogeneity of effect-measure estimates was investigated using meta-regression. Six novel associations of body mass index loci with age at menarche were identified, and 11 adiposity loci previously reported to be associated with age at menarche were confirmed, but none of the central adiposity variants individually showed significant associations. These findings suggest complex genetic relationships between menarche and overall obesity, and to a lesser extent central obesity, in normal processes of growth and development.

Relationships Between Health Behaviors and Weight Status in American Indian and White Rural Children

Preventing obesity in childhood is an increasingly important public health goal. Prevention efforts can be improved by better understanding relationships between health behaviors and overweight and obesity. This study examined such relationships in young American Indian and white children living in the rural United States. Self-report measures of diet, screen time (passive and active), and physical activity were combined with cardiovascular fitness in cross-sectional analyses to predict weight categories based on body mass index percentiles in 306 American Indian and white children (aged 8-9 years) from a rural area in the upper Midwestern United States. Multinomial logistic regression models were statistically significant for girls (χ2 [20] = 42.73, P < .01), boys (χ2 [20] = 50.44, P < .001), American Indian (χ2 [20] = 36.67, P < .05), and white children (χ2 [20] = 55.99, P < .001). Obesity was associated with poorer cardiovascular fitness in girls (OR = 0.82), boys (OR = 0.83), American Indian (OR = 0.79), and white children (OR = 0.85), and with passive screen time in girls (OR = 1.69), boys (OR = 2.1), and white children (OR = 1.81). Overweight was associated with passive screen time (OR = 2.24) and inversely with active screen time (OR = 0.54), but only in boys. Logistic regression models were more successful at predicting obesity than overweight in all groups of participants. Poorer cardiovascular fitness showed the strongest and most consistent association with obesity, but passive screen time was also a significant and important contributor to the prediction of obesity in most prediction models. Prediction models were similar in girls, boys, American Indian, and white children.

Differences in Health Behavior, Physical Fitness, and Cardiovascular Risk in Early, Average, and Late Mature Children

This study examined the association between biological maturity, CVD risk, fitness and health behavior in 709 (359 male, 350 female) 8-year-old children (range: 6.3-8.9 years). Sports participation and sedentary behavior was assessed via parent questionnaire. Height and weight was measured and maturity status was predicted based on % of adult-height reached. Fitness was assessed via a test battery and CVD risk was determined using mean arterial pressure, cholesterol and intra-abdominal fat. BMIpercentiles (BMIPCT) differed significantly among early, average and late maturing children. Early maturing children displayed a higher CVD risk profile (0.5 vs. -0.2), lower fitness scores (-0.4 vs. 0.2), and spent more time watching TV (51 vs. 43 min/day) compared with their peers. After controlling for BMIPCT differences remained only for fitness in boys and TV time in girls.

Long‐term changes in BMI and adiposity rebound among girls from Kraków (Poland) over the last 30 years (from 1983 to 2010)

Early adiposity rebound (AR, below 5 years) is an important predictor of adult obesity. The main purpose of this study was to explore changes in body weight and height, BMI, body fat, and AR timing in girls from Krakow within the last 3 decades. 1,970 girls were measured in 2010. Using the results of body height, weight and skin folds measurements, the BMI and %BF was calculated. The LMS method was used to constructed BMI and %BF centiles. Three fractions were distinguished in individual age groups of the subjects-below the 15th percentile (underweight girls), 50th percentile and above 85th percentile (overweight girls). These data were compared with the results from previous survey series (1983 and 2000). The mean age of the menarche onset were calculated by means of the probit method. The girls from last series are taller and heavier than girls measured in 1983. Before the time of AR, girls from last series have lowest BMI and %BF than girls from the first series. In spite of this, all girls measured in 2010 have the time of AR earlier than girls measured in 1983. The girls from the last series of measurements showed also acceleration of sexual maturation and the average menarche age was the earliest in them and equalled 12.68 years. AR cannot be explained only by changes in body adiposity. Early AR could be a marker of acceleration of development already in an early postnatal ontogenesis.