Body size and fatness in young adults in relation to age at menarche

Body structure and maturation – the association with environmental factors

The main objective of the study was to determine the relationship between physique, maturation and some environmental factors. The study was conducted in Warsaw, between 2012 and 2013 in randomly selected schools. The material included 171 girls, aged 12–20 years. Body height and weight, upper and lower extremity length, subcutaneous fat folds on arm, subscapular and abdominal, circumferences of arm, chest, waist and hip were measured. Body proportion indices were calculated. The questionnaire form provided information on parental education and profession, and the number of children in family. Girls were asked about age at menarche, number of daily meals, level of physical activity, participation is sport, and level of stress at home and at school. The principal component analysis was applied and 4 factors were extracted from the set of living condition characteristics (F1 – Parental education & father’s occupation, F2 – Mother’s occupation and the number of children, F3 – Stress, F4 – Physical activity and number of daily meals). Regression analysis allowed to evaluate the association of body build characteristics and age at menarche with the four factors. Factor 1 and 4 were the only ones which showed a statistically significant association with body build. The results showed that girls who were taller, with smaller arm and waist circumferences and less adiposity came from families with higher parental education and better father’s profession. Taller stature, longer legs and less adiposity characterized girls who were more physically active and consumed more than three meals a day.

Sex-specific trajectories of systolic and diastolic blood pressure in youth

BACKGROUND AND OBJECTIVE

High blood pressure early in life is associated with cardiovascular disease morbidity and mortality in adulthood. The objective was to identify sex-specific trajectories of SBP and DBP from early adolescence to early adulthood and to assess the impact of modifiable factors on the trajectories, including BMI, smoking, alcohol use, physical activity, and screen-time.

METHODS

Data were drawn from four waves of a prospective investigation of 1294 youth aged 12-13 years at inception and followed until age 24 years. Group-based trajectory models were used to identify trajectories and assess the impact of modifiable factors in 403 men and 432 women.

RESULTS

Three SBP trajectories were identified in men [corresponding to low (43.2%), medium (45.2%), and high SBP (11.7%)] and women [corresponding to low (48.1%), medium (44.7%), and high SBP (7.2%)]. Similar results were observed for DBP in both sexes. BMI and smoking were associated with higher SBP and DBP values in most trajectory groups, whereas screen-time in both sexes and physical activity in women were associated with high SBP trajectories only.

CONCLUSION

There is heterogeneity in the sex-specific natural course of SBP and DBP in youth and in the magnitude of the effect of modifiable factors on SBP and DBP across trajectories. Distinguishing trajectories allows identification of subgroups at risk of hypertension and cardiovascular disease later in life and in addition can inform the design of targeted interventions to attenuate high SBP and DBP trajectories over time and maintain normal trajectories.

Maternal fish oil supplementation during lactation is associated with reduced height at 13 years of age and higher blood pressure in boys only

Dietary long-chain n-3 PUFA (n-3 LCPUFA) in infancy may have long-term effects on lifestyle disease risk. The present follow-up study investigated whether maternal fish oil (FO) supplementation during lactation affected growth and blood pressure in adolescents and whether the effects differed between boys and girls. Mother-infant pairs (n 103) completed a randomised controlled trial with FO (1·5 g/d n-3 LCPUFA) or olive oil (OO) supplements during the first 4 months of lactation; forty-seven mother-infant pairs with high fish intake were followed-up for 4 months as the reference group. We also followed-up 100 children with assessment of growth, blood pressure, diet by FFQ and physical activity by 7-d accelerometry at 13·5 (sd 0·4) years of age. Dried whole-blood fatty acid composition was analysed in a subgroup (n 49). At 13 years of age, whole-blood n-3 LCPUFA, diet, physical activity and body composition did not differ between the three groups. The children from the FO group were 3·4 (95 % CI 0·2, 6·6) cm shorter (P=0·035) than those from the OO group, and tended to have less advanced puberty (P=0·068), which explained the difference in height. There was a sex-specific effect on diastolic blood pressure (P sex×group=0·020), which was driven by a 3·9 (95 % CI 0·2, 7·5) mmHg higher diastolic blood pressure in the FO compared with the OO group among boys only (P=0·041). Our results indicate that early n-3 LCPUFA intake may reduce height in early adolescence due to a delay in pubertal maturation and increase blood pressure specifically in boys, thereby tending to counteract existing sex differences.

Pubertal Development and Prepubertal Height and Weight Jointly Predict Young Adult Height and Body Mass Index in a Prospective Study in South Africa

BACKGROUND

Height and adiposity track over childhood, but few studies, to our knowledge, have longitudinally examined the mediating relation of the timing and progression of puberty.

OBJECTIVE

We assessed interrelations between prepubertal height and body mass index, the progression through puberty, and young adult height and adiposity.

METHODS

We analyzed data from the Birth to Twenty Plus study (females, n = 823; males, n = 765). Serial measures of anthropometry and pubertal development were obtained between ages 9 and 16 y. We used latent class growth analysis to categorize pubertal development with respect to pubic hair (females and males), breasts (females), and genitalia (males) development. Adult height and weight were obtained at ages 18 to 20 y.

RESULTS

Among females, higher latent class (earlier initiation and faster progression through puberty) was associated with an increased risk of obesity [pubic hair class 3 compared with class 1: RR, 3.41 (95% CI: 1.57, 7.44)] and inconsistent associations with height. Among males, higher latent class was associated with increased adult height [pubic hair development class 3 compared with class 1: 2.43 cm (95% CI: 0.88, 4.00)] and increased risk of overweight/obesity [pubic hair development class 3 compared with class 1: OR, 3.44 (95% CI: 1.44, 8.20)]. In females, the association with adult height became inverse after adjusting for prepubertal height [pubic hair development class 3 compared with class 1: females, -1.31 cm (95% CI: -2.32, -0.31)]; in males, the association with height was attenuated with this adjustment [-0.56 cm (95% CI: -1.63, 0.52)]. Associations with adiposity were attenuated after adjusting for prepubertal adiposity.

CONCLUSIONS

Progression through puberty modifies the relation between prepubertal and adult anthropometry. Screening for early or rapid progression of puberty might identify children at an increased risk of becoming overweight or obese adults.

Early Life Growth Predicts Pubertal Development in South African Adolescents

BACKGROUND

Given global trends toward earlier onset of puberty and the adverse psychosocial consequences of early puberty, it is important to understand the childhood predictors of pubertal timing and tempo.

OBJECTIVE

We examined the association between early growth and the timing and tempo of puberty in adolescents in South Africa.

METHODS

We analyzed prospectively collected data from 1060 boys and 1135 girls participating in the Birth-to-Twenty cohort in Soweto, South Africa. Height-for-age z scores (HAZs) and body mass index-for-age z scores (BMIZs) were calculated based on height (centimeters) and body mass index (kilograms per meter squared) at ages 5 y and 8 y. The development of genitals, breasts, and pubic hair was recorded annually from 9 to 16 y of age with the use of the Tanner sexual maturation scale (SMS). We used latent class growth analysis to identify pubertal trajectory classes and also characterized children as fast or slow developers based on the SMS score at 12 y of age. We used multinomial logistic regression to estimate associations of HAZ and BMIZ at ages 5 and 8 y with pubertal development.

RESULTS

We identified 3 classes for pubic hair development (for both girls and boys) and 4 classes for breast (for girls) and genital (for boys) development. In girls, both HAZ and BMIZ at age 5 y were positively associated with pubic hair development [relative risk ratio (RRR): 1.57, P < 0.001 and RRR: 1.51, P < 0.01, respectively], as was BMI at age 8 y (RRR: 2.06, P = 0.03); similar findings were observed for breast development. In boys, HAZ and BMIZ at age 5 y were positively associated with pubic hair development (RRR: 1.78, P < 0.001 and RRR: 1.43, P < 0.01, respectively); HAZ at age 5 y was associated with development of genitals (RRR: 2.19, P < 0.01).

CONCLUSION

In boys and girls, both height and body mass index in early childhood predicted the trajectory of pubertal development. This may provide a tool to identify children at risk of early pubertal onset.

Early stress predicts age at menarche and first birth, adult attachment, and expected lifespan

Life history theory suggests that in risky and uncertain environments the optimal reproductive strategy is to reproduce early in order to maximize the probability of leaving any descendants at all. The fact that early menarche facilitates early reproduction provides an adaptationist rationale for our first two hypotheses: that women who experience more risky and uncertain environments early in life would have (1) earlier menarche and (2) earlier first births than women who experience less stress at an early age. Attachment theory and research provide the rationale for our second two hypotheses: that the subjective early experience of risky and uncertain environments (insecurity) is (3) part of an evolved mechanism for entraining alternative reproductive strategies contingent on environmental risk and uncertainty and (4) reflected in expected lifespan. Evidence from our pilot study of 100 women attending antenatal clinics at a large metropolitan hospital is consistent with all four hypotheses: Women reporting more troubled family relations early in life had earlier menarche, earlier first birth, were more likely to identify with insecure adult attachment styles, and expected shorter lifespans. Multivariate analyses show that early stress directly affected age at menarche and first birth, affected adult attachment in interaction with expected lifespan, but had no effect on expected lifespan, where its original effect was taken over by interactions between age at menarche and adult attachment as well as age at first birth and adult attachment. We discuss our results in terms of the need to combine evolutionary and developmental perspectives and the relation between early stress in general and father absence in particular.

The evolutionary ecology of attachment organization

Life history theory's principle of allocation suggests that because immature organisms cannot expend reproductive effort, the major trade-off facing juveniles will be the one between survival, on one hand, and growth and development, on the other. As a consequence, infants and children might be expected to possess psychobiological mechanisms for optimizing this trade-off. The main argument of this paper is that the attachment process serves this function and that individual differences in attachment organization (secure, insecure, and possibly others) may represent facultative adaptations to conditions of risk and uncertainty that were probably recurrent in the environment of human evolutionary adaptedness.

Bivariate genome-wide association analyses identified genes with pleiotropic effects for femoral neck bone geometry and age at menarche

Femoral neck geometric parameters (FNGPs), which include cortical thickness (CT), periosteal diameter (W), buckling ratio (BR), cross-sectional area (CSA), and section modulus (Z), contribute to bone strength and may predict hip fracture risk. Age at menarche (AAM) is an important risk factor for osteoporosis and bone fractures in women. Some FNGPs are genetically correlated with AAM. In this study, we performed a bivariate genome-wide association study (GWAS) to identify new candidate genes responsible for both FNGPs and AAM. In the discovery stage, we tested 760,794 SNPs in 1,728 unrelated Caucasian subject, followed by replication analyses in independent samples of US Caucasians (with 501 subjects) and Chinese (with 826 subjects). We found six SNPs that were associated with FNGPs and AAM. These SNPs are located in three genes (i.e. NRCAM, IDS and LOC148145), suggesting these three genes may co-regulate FNGPs and AAM. Our findings may help improve the understanding of genetic architecture and pathophysiological mechanisms underlying both osteoporosis and AAM.

Childhood adversity and pubertal timing: understanding the origins of adulthood cardiovascular risk

OBJECTIVE

To determine whether greater childhood adversity relates to younger menarcheal age; whether younger menarcheal age relates to increased CVD risk; and whether greater childhood adversity relates to increased CVD risk, directly or indirectly (mediated by menarcheal age).

METHODS

Among 650 pre-menopausal women (ages 25-45; M=34.9[5.6]), SEM was performed to estimate relations between childhood adversity, menarcheal age, and CVD risk.

RESULTS

Results supported a covariate-adjusted model (RMSEA=0.035; CFI=0.983) in which greater childhood adversity was related to younger menarcheal age (β=-.13, p<.01) and younger menarcheal age was related to greater CVD risk (β=-.18, p<.05). Direct and indirect effects of childhood adversity on CVD risk were non-significant. Re-evaluation of the same model with additional covariate-adjustment for adulthood body composition showed the relation between menarcheal age and CVD risk attenuated (β=-.03, p=.376).

CONCLUSIONS

Cross-sectional evidence suggests family-related adversity experiences in childhood confer risk for earlier menarche which, in turn, relates to increased CVD risk in adulthood, possibly via post-pubertal body size.

Pubertal timing, androgens, and obesity phenotypes in women at midlife

CONTEXT

Individuals with metabolically healthy or benign obesity vs. unhealthy or at risk obesity have been distinguished; however, the predisposing factors for developing these phenotypes are poorly understood.

OBJECTIVE

Our objective was to examine pubertal timing marked by menarcheal age in relation to at-risk obese, benign obese, and healthy normal-weight phenotypes at midlife and to characterize the potential role of androgens, marked by the free androgen index (FAI), in accounting for any associations between menarcheal age and obesity phenotype.

DESIGN

The study was cross-sectional.

SETTING AND PARTICIPANTS

Participants included a multiethnic community sample of 989 premenopausal women ages 25-45 yr (mean=35.2 yr; sd=5.5 yr).

MAIN OUTCOME MEASURE

Membership in at-risk obese, benign obese, and healthy normal-weight groups was defined by body mass index and number of metabolic syndrome components.

RESULTS

With each 1-yr increase in menarcheal age, the probability of having the at-risk obese compared with the healthy normal-weight phenotype decreased by 22%. This association attenuated when FAI was covaried, suggesting androgen levels may account for this association. In addition, higher FAI was independently related to having the at-risk obese compared with the healthy normal-weight phenotype as well as having the at-risk compared with the benign obese phenotype (all P<0.05).

CONCLUSIONS

Younger menarcheal age is associated with having the metabolically unhealthy obesity phenotype compared with the healthy normal-weight phenotype at midlife. This relation may be driven by levels of bioavailable androgens, which were especially elevated among women with the at-risk obesity phenotype.

Age and size at maturity in women: a norm of reaction?

OBJECTIVES

We present the first review and meta-analysis of the association between adult stature and age at menarche over a broad range of human societies. We then outline possible biological explanations for observed empirical associations.

METHODS

We analyzed the association between adult stature and age at menarche in 141 samples from published reports, including 35 samples for which the within-sample association was also reported.

RESULTS

Overall and in small-scale societies, later age at menarche is associated with shorter adult stature. However, both between and within samples from industrialized societies, later age at menarche is associated with taller adult stature.

CONCLUSIONS

The pattern of associations between adult stature and age at menarche may be explicable as a norm of reaction that evolved according to predictions of life history theory. However, nonadaptive explanations are also plausible, especially for the positive association observed in industrialized societies.

The relation of menarcheal age to anthropometric profiles in Korean girls

The aim of this study was to represent the trend of early menarche and to assess the association of age at menarche with anthropometric profiles of Korean children and adolescents. A cross sectional survey was conducted with 13,371 girls aged 10 to 18 yr, recruited nationwide from April, 2005 to March, 2006. Height, weight and waist circumference of the subjects were measured; and the subjects self-reported their ages at menarche. We found that the menarcheal girls were taller (P<0.05 for the girls between 10 and 14 yr) and heavier (P<0.05 for the girls between 10 and 18 yr) than non-menarcheal ones. Menarcheal girls also showed higher body mass index (BMI), and greater waist circumference than non-menarcheal ones. Significant differences were represented according to the age at menarche in terms of BMI, waist circumference, % body fat mass, waist hip ratio and neck circumference as well as height and weight (P<0.05). In conclusion, girls who matured early were taller and heavier in early adolescence than those who matured later.

Development's tortoise and hare: pubertal timing, pubertal tempo, and depressive symptoms in boys and girls

Although the sequence of pubertal maturation remains consistent across most individuals, the timing and tempo of development fluctuate widely. While past research has largely focused on the sequelae of pubertal timing, a faster tempo of maturation might also present special challenges to children for acclimating to new biological and social milestones. Using latent growth curve modeling, the present study investigated how pubertal tempo and pubertal timing predicted depressive symptoms over a 4-year period in a sample of children recruited from New York City area public schools. Rate of intraindividual change in parent-reported Tanner stages was used as an index of pubertal tempo, and more advanced Tanner development at an earlier chronological age was used as an index of pubertal timing. For girls (N = 138, M = 8.86 years old at Time 1), pubertal timing emerged as the most salient factor, and the tempo at which girls progressed through puberty was not significant. In boys (N = 128, M = 9.61 years old at Time 1), both timing and tempo of development were significant; notably, however, the effects of pubertal tempo were stronger than those of timing. These findings highlight the need to consider multiple sources of individual variability in pubertal development and suggest different pubertal challenges for boys and girls.

Age at menarche, abnormal glucose tolerance and type 2 diabetes mellitus: The Rancho Bernardo Study

OBJECTIVE

We examined the association of age at menarche with risk of abnormal glucose tolerance (AGT) and type 2 diabetes in postmenopausal women.

METHODS

Participants were 997 women aged 50-92 years who had a clinic visit in 1984-87, when reproductive and diabetes history were recorded, and an oral glucose tolerance test administered. Information on age at menarche was collected in 1989. Diabetes status was based on WHO 1999 criteria, and AGT on having impaired fasting glucose (IFG) or impaired glucose tolerance (IGT).

RESULTS

The average age was 69.5 years; 12.5% had diabetes and 29.8% had AGT. Menarche was < 12 years in 14.5%, 12-15 years in 78.9% and > or = 16 years in 6.6%. Age and body mass index (BMI) predicted AGT (p < 0.001, p = 0.003, respectively), while age, BMI and family history of diabetes predicted type 2 diabetes (p < 0.001, p < 0.001, p = 0.02, respectively). Polynomial logistic regression showed no association of menarche with AGT or type 2 diabetes risk. In linear regressions, however, older age at menarche was associated with lower fasting (p = 0.01) and post-challenge plasma glucose (p = 0.03). Covariates, especially BMI, weakened these associations, although women with menarche > or = 16 years still had lower post-challenge (0.86 mmol/l, p = 0.05) and fasting glucose (0.26 mmol/l, p = 0.11) than those with menarche < 12 years.

CONCLUSIONS

Age at menarche was not associated with AGT or type 2 diabetes risk. Late age at menarche was inversely associated with fasting and post-challenge glycemia. Obesity may mediate the observed associations.

Pre-pregnancy body mass index among pregnant adolescents: gestational weight gain and long-term post partum weight retention

STUDY OBJECTIVE

To determine the relationship between adolescents' pre-pregnancy body mass index (BMI), and gestational weight gain and postpartum weight retention.

DESIGN

We review the medical records of adolescents participating in a prospective cohort study on comprehensive health care and parenting education to determine pre-pregnancy BMI, gestational weight gain, and postpartum weight retention at one year.

SETTING

Urban academic hospital clinic.

PARTICIPANTS

102 pregnant adolescents aged 15-21 years.

MAIN OUTCOMES

Gestational weight gain and weight retention at one year postpartum.

RESULTS AND CONCLUSIONS

Fifty-two (51%) adolescent women had normal pre-pregnancy BMI according to the Institute of Medicine classification. Adolescent women with normal (36.5%) and high pre-pregnancy BMI (66.5%) were more likely than women with low pre-pregnancy BMI (26.5%) to exceed recommended gestational weight gain. Adolescent women who exceeded recommended weight gain retained significantly more weight at 1 year postpartum than women with weight gain within or below the recommendation. In a linear regression model that controlled for age, smoking, pregnancy complication, and post partum contraceptive use, pre-pregnancy BMI and gestational weight gain were the strongest predictors of postpartum weight retention at 1 year. A normal to high pre-pregnancy BMI and excessive gestational weight gain are important predictors of postpartum weight retention in adolescents. These two predictors must be monitored systematically with the aim of preventing postpartum obesity and its associated diseases among this population.

Maturational tempo differences in relation to the timing of the onset of puberty in girls

AIM

To determine maturational tempo differences related to the timing of pubertal onset in girls.

METHODS

We studied longitudinally 307 prepubertal Greek schoolgirls. Age at onset of puberty (B2), peak height velocity (PHV) and age at menarche were recorded. Age at onset of puberty quartiles were determined in order to define girls as early maturers (<9.2 years) and late maturers (>10.6 years). Due to dropout from the study, results for menarche are reported for 182 girls.

RESULTS

Median (1st-3rd quartile) time span from B2 to PHV was longer for early maturers than for average and late maturers, 1.6 (1.0-2.2) years, 1.1 (0.7-1.7) years and 0.9 (0.3-1.1) years, respectively, p < 0.001). There was no significant difference in PHV, in the time interval from PHV to menarche and in adult height (for 75 girls) with respect to whether girls matured early, average or late.

CONCLUSION

A compensatory delay in the maturational tempo in early-maturing girls and a catch-up mechanism in late-maturing girls was shown. The maturational differences manifest as differences in the time span from the onset of puberty to PHV. Early pubertal maturation in girls does not compromise adult height and is not always followed by early menarche.

Genetic factors in physical growth and development and their relationship to subsequent health outcomes

Normal physical growth during childhood is influenced by both genetic and environmental factors. However, few studies have examined whether there are shared genetic effects between aspects of child growth and later health outcomes. In this study, we estimate the influence of genetic factors on growth in stature during childhood and determine whether there are pleiotropic effects of genes influencing both childhood growth and later adult health outcomes using familial data. Serial stature data (i.e., birth through adulthood) from participants in the Fels Longitudinal Study were used to derive stature growth parameters. Adult health outcome data for each participant were available for at least one visit after age 30 years. Maximum likelihood-based variance component methods were used to determine the heritability of each parameter and to examine the relationships between growth parameters and adult health outcomes by estimating genetic correlations between the traits. Heritability estimates for the growth parameters are generally high and statistically significant ranging in magnitude from 0.65-0.98. Heritabilities for adult health outcomes are also significant ranging from 0.31-0.98. Results of the phenotypic correlation analysis show that stature growth parameters are significantly related to several adult health outcomes including stature, weight, BMI, systolic and diastolic blood pressure, percent body fat, fat-free mass, skeletal muscle mass in the arms and legs, and total body bone mass. Results of the genetic correlation analysis reveal some evidence of common genetic pathways underlying certain aspects of growth and adult health outcomes including body composition and blood pressure variables.

Family structure and age at menarche: a children-of-twins approach

Girls who grow up in households with an unrelated adult male reach menarche earlier than peers, a finding hypothesized to be an evolutionary strategy for families under stress. The authors tested the alternative hypothesis that nonrandom selection into stepfathering due to shared environmental and/or genetic predispositions creates a spurious relation between stepfathering and early menarche. Using the unique controls for genetic and shared environmental experiences offered by the children-of-twins design, the authors found that cousins discordant for stepfathering did not differ in age of menarche. Moreover, controlling for mother's age of menarche eliminated differences in menarcheal age associated with stepfathering in unrelated girls. These findings strongly suggest selection, and not causation, accounts for the relationship between stepfathering and early menarche.

Childhood overweight and maturational timing in the development of adult overweight and fatness: the Newton Girls Study and its follow-up

OBJECTIVE

Although several studies have suggested that early menarche is associated with the development of adult overweight, few have accounted for childhood overweight before menarche.

STUDY DESIGN

A 30-year follow-up of the original participants in the Newton Girls Study, a prospective study of development in a cohort of girls followed through menarche, provided data on premenarcheal relative weight and overweight (BMI >85th percentile), prospectively obtained age at menarche, self-reported adult BMI, overweight (BMI > 25), obesity (BMI > 30) and, for a subset of participants, percentage body fat by dual-energy x-ray absorptiometry.

RESULTS

Of the 448 women who participated in the adult follow-up at a mean age of 42.1 years (SD: 0.76 years), 307 had childhood data with which to characterize premenarcheal and menarcheal weight status and age at menarche. After a follow-up of 30.1 years (SD: 1.4 years), reported BMI was 23.4 (4.8), 28% were overweight, and 9% were obese. In multivariate linear and logistic-regression analyses, almost all of the influence on adult weight status was a result of premenarcheal weight status (model R2 = 0.199). Inclusion of a variable to reflect menarcheal timing provided very little additional information (model R2 = 0.208). Girls who were overweight before menarche were 7.7 times more likely to be overweight as adults (95% confidence interval: 2.3, 25.8), whereas early menarche (at < or = 12 years of age) did not elevate risk (odds ratio: 1.3, 95% confidence interval: 0.66, 2.43). A similar pattern of results was observed when percentage body fat in adulthood was evaluated.

CONCLUSIONS

The apparent influence of early maturation on adult female overweight is largely a result of the influence of elevated relative weight on early maturation. Interventions to prevent and treat overweight should focus on girls before they begin puberty.

Early menarche and the development of cardiovascular disease risk factors in adolescent girls: the Fels Longitudinal Study

The purpose of this study was to evaluate the influence of menarcheal age on changes in insulin, glucose, lipids, and blood pressure during adolescence and to assess whether body composition modifies this relationship. We examined 391 girls, a subset of Fels Longitudinal Study female participants (8-21 yr of age). Self-reported menarcheal age was classified based on the National Health and Nutrition Examination Survey III distribution, in which early menarche was at the 25th percentile or less (11.9 yr). Age at menarche was examined in relation to measures of body composition [e.g. fat-free mass (FFM) and percent body fat (PBF)], insulin resistance, blood pressure, and lipid profile. The effects of menarcheal age and body composition on cardiovascular disease risk factor changes were analyzed with serial data mixed models. Median menarcheal age was 12.7 yr (range, 9.8-17.0 yr), with 91 girls (23%) classified as early menarche. Girls with early menarche had more deleterious changes in insulin, glucose, blood pressure, FFM, and PBF levels than girls with average or late menarche. Menarcheal age adversely affected cardiovascular disease risk factor changes independent of age and changes in FFM or PBF. Girls with early menarche exhibited elevated blood pressure and glucose intolerance compared with later maturing girls, independent of body composition.

Timing of pubertal maturation in girls: an integrated life history approach

Life history theory provides a metatheoretical framework for the study of pubertal timing from an evolutionary-developmental perspective. The current article reviews 5 middle-level theories--energetics theory, stress-suppression theory, psychosocial acceleration theory, paternal investment theory, and child development theory--each of which applies the basic assumptions of life history theory to the question of environmental influences on timing of puberty in girls. These theories converge in their conceptualization of pubertal timing as responsive to ecological conditions but diverge in their conceptualization of (a) the nature, extent, and direction of environmental influences and (b) the effects of pubertal timing on other reproductive variables. Competing hypotheses derived from the 5 perspectives are evaluated. An extension of W. T. Boyce and B. J. Ellis's (in press) theory of stress reactivity is proposed to account for both inhibiting and accelerating effects of psychosocial stress on timing of pubertal development. This review highlights the multiplicity of (often unrecognized) perspectives guiding research, raises challenges to virtually all of these, and presents an alternative framework in an effort to move research forward in this arena of multidisciplinary inquiry.

The maturation rate of girls living in rich and poor rural regions of Poland before and after the transformation of 1989

The aim of this study was to find out whether the political and economic system transformation in Poland in 1989 had an influence on the rate of maturation of girls from various categories of the rural population in two regions, differing in wealth. The stratification of the villagers was based on the source of the family income (farmers, farmer-workers and non-farmers), on parents' education, and on the number of children per family. The age at menarche (AM) was used as biological indicator of living conditions. Rural girls aged 9.5-18.5 years were studied in 1987 in Leszno (L), a rich region (n = 2049), and in 1989 in Suwałki (S), a poor region (n = 2077). The study was repeated in 2001 in the same villages, the numbers of subjects amounting to 2440 and 2122, respectively. In the 1980s, AM in regions L and S amounted to 13.18 and 13.88 years, respectively, and was strongly related to social stratification. The earliest AM was found in daughters of non-farmers and the latest in the girls from farmers' families. In 2001, the acceleration in AM amounted to 0.14 years in the rich region and to 0.46 years in the poor region. The percentage of families owning a car, freezer, colour TV and automatic washing machine markedly increased and the education of parents improved. Such results are indicative of an improvement in the living standard of the groups investigated, but the villagers regard themselves as the losers as a result of the system transformation in Poland. Since the Polish population is considered as ethnically homogenous, the great differences in AM within the rural population, as well as the differences between the inhabitants of villages and large cities should be regarded as biological effects of social inequalities. Such differences indicate that Polish rural girls are far below the genetic potential for menarcheal age.

Age at menarche and age of onset of pubertal characteristics in 6-14-year-old girls from the Province of L'Aquila (Abruzzo, Italy)

The present study is part of a research project on growth models of children in an area of central-southern Italy. It analyzes the phases of pubertal breast development (BD) in 397 girls, pubic hair development (PHD) in 399 girls, and menarche in 583 girls from 6-14 years old. The status quo method was used to evaluate the age at menarche. Probit analysis was used to analyze the data for all three variables. The onset of BD and PHD (Tanner stage 2) occurs at age 7 in 6.1% of girls. Passage to stage 3 of one or both secondary sexual characteristics occurs at age 10 in 8.5% of girls. Comparison with data from the United States shows higher percentages of American white girls in stage 2 (or greater) of both characteristics at any age. The mean (median) age of onset (Tanner stage 2) of BD or PHD or both of them is 9.96 years. The passage to stage 3 occurs at age 12.36 for BD (95% confidence interval: 1.36 years) and at age 12.10 for PHD (95% confidence interval: 0.51 years). The mean age at menarche is 12.55 years, in general agreement with other values found in Italy. Sexual maturation at any considered stage for both pubertal characteristics is generally in line with literature data concerning other Mediterranean and industrialized countries or countries in which the demographic transition is in an advanced phase. It does not show a significant earlier onset. The evidence emerging from the general project suggests that the secular trend is still in progress in this region of Italy.

Longitudinal changes in risk variables underlying metabolic Syndrome X from childhood to young adulthood in female subjects with a history of early menarche: the Bogalusa Heart Study

OBJECTIVES

To examine the longitudinal changes in adiposity and related risk variables of Syndrome X from childhood to young adulthood with respect to early onset of menarche.

DESIGN

Community-based longitudinal cohort of female subject (65% white, 35% blacks subjects) who participated in two or more surveys from childhood to young adulthood and had reported their menarcheal age (<12 y, n=437 vs > or =12 y, n=1042).

RESULTS

In childhood (5-11 y), adolescence (12-18 y), and young adulthood (19-37 y), females with early menarche displayed significantly higher body mass index (BMI) and triceps skinfold thickness; higher stature in childhood and adolescence; higher fasting insulin and homeostasis model assessment index of insulin resistance (HOMA-IR) in childhood and adulthood; and higher fasting glucose in adulthood. Blood pressure and lipoprotein variables showed no early menarche-related differences. Longitudinal rates of change in BMI (P=0.002), triceps skinfold thickness (P=0.05), insulin (P=0.09), and HOMA-IR (P=0.05) were positive and faster among female subjects with early menarche; fasting glucose decreased slowly in this group (P=0.006). In a multivariate analysis, body fatness and insulin related independently to early menarche (P<0.001). This association was stronger in white subjects (P=0.0008). In adulthood, the prevalence of clustering of three to four risk factors of syndrome X (highest quartile of: (1) BMI, (2) fasting insulin, (3) systolic or mean arterial pressure, and (4) total cholesterol to HDL cholesterol or triglycerides to HDL cholesterol ratio specific for age, race, and study year) was higher among those with early menarche (10.7 vs 6.2%, P=0.002). The odds for developing such clustering in adulthood among those with early menarche was 1.54 (95% CI=1.14-2.07), regardless of race.

CONCLUSION

Early menarche is characterized by excess body fatness and insulin beginning in early childhood and higher prevalence of clustering of adverse levels of risk variables of metabolic Syndrome X in young adulthood.

Evolutionary perspectives on pregnancy: maternal age at menarche and infant birth weight

We present a novel evolutionary analysis of low birth weight (LBW). LBW is a well-known risk factor for increased infant morbidity and mortality. Its causes, however, remain obscure and there is a vital need for new approaches. Life history theory, the most dynamic branch of evolutionary ecology, provides important insights into the potential role of LBW in human reproductive strategies. Life history theory's primary rationale for LBW is the trade-off between current and future reproduction. This trade-off underlies the prediction that under conditions of environmental risk and uncertainty (experienced subjectively as psychosocial stress) it can be evolutionarily adaptive to reproduce at a young age. One component of early reproduction is early menarche. Early reproduction tends to maximise offspring quantity, but parental investment theory's assumption of a quantity-quality trade-off holds that maximizing offspring quantity reduces quality, of which LBW may be the major component. We therefore predict that women who experienced early psychosocial stress and had early menarche are more likely to produce LBW babies. Furthermore, the extension of parent-offspring conflict theory in utero suggests that the fetus will attempt to resist its mother's efforts to reduce its resources, allocating more of what it does receive to the placenta in order to extract more maternal resources to increase its own quality. We propose that LBW babies born to mothers who experience early psychosocial stress and have early menarche are more likely to have a higher placental/fetal weight ratio. We review evidence in support of these hypotheses and discuss the implications for public health.

Pubertal maturation in girls and the relationship to anthropometric changes: pathways through puberty

OBJECTIVE

Patterns of pubertal maturation may have an impact on several risk factors associated with adult morbidity and mortality, such as obesity. We examined the relationship of the initial manifestation of puberty in girls with anthropometric measures, as well as age at menarche.

METHODS

White females (n = 1166, ages 9 and 10 at intake) were followed with annual visits for 10 years. Physical examinations included height, weight, skinfold thicknesses, and pubertal maturation assessment.

RESULTS

During the course of the study, 443 of 859 eligible females (51.6%) were observed to have asynchronous maturation in the development of puberty, that is, initial areolar/breast (thelarche pathway) or pubic hair (adrenarche pathway) development, without development of the other characteristic. Using a longitudinal regression model, significant interactions were noted between initial pubertal manifestation and years since onset of puberty on the following outcomes: sum of skinfolds thickness, percent body fat, waist-to-hip ratio, and body mass index (BMI). However, age of onset of pubertal maturation was the same in the 2 groups (10.7 years). Females in the thelarche pathway had earlier menarche (12.6 vs 13.1 years) as well as greater skinfolds, body fat, and BMI at the time of menarche. Females in the thelarche pathway also had greater body fat and BMI 1 year before puberty and throughout puberty compared with those in the adrenarche pathway.

CONCLUSIONS

Females who enter puberty through the thelarche pathway, as compared with the adrenarche pathway, had greater sum of skinfold thicknesses, BMI, and percent body fat 1 year before the onset, as well as throughout, puberty. Because larger body composition and earlier age of menarche of females in the thelarche pathway parallel the epidemiologic profiles of women who are obese or at risk for obesity, these females may be at greater risk for adult obesity.

The relation of menarcheal age to obesity in childhood and adulthood: the Bogalusa heart study

BACKGROUND

Several studies have shown that girls who undergo menarche at a relatively young age tend to be more obese as adults. However, because childhood (pre-menarcheal) levels of weight and height are associated with an earlier menarche, the increased prevalence of adult obesity among early maturers may largely reflect the persistence of childhood obesity into adulthood.

METHODS

We examined these interrelationships among 1179 girls (65% white, 35% black) who were examined as children (mean age, 9 y), adolescents, and adults (mean age, 26 y) in the Bogalusa Heart Study.

RESULTS

Both white and black women who reported that they underwent menarche before age 12 y had, on average, higher adult levels of weight (+10 kg), body mass index (BMI, +4 kg/m2) and skinfold thicknesses (+6 mm) than did women who underwent menarche after age 13.5 y. However, relatively fat children tended to undergo menarche earlier than did thinner children, with each standard deviation increase in pre-menarcheal BMI increasing the odds of early menarche (<12 y) by approximately 2-fold. Stratified and regression analyses indicated that (1) adult obesity was more strongly associated with childhood obesity than with menarcheal age, and (2) about 60% to 75% of the apparent effect of menarcheal age was due to the influence of childhood obesity on both menarcheal age and adult obesity.

CONCLUSIONS

Although additional longitudinal studies are needed, it is likely that the importance of early menarche in adult obesity has been overestimated. Most of apparent influence of menarcheal age on adult obesity is attributable to the association of childhood obesity with both menarcheal age and adult obesity.

Is obesity associated with early sexual maturation? A comparison of the association in American boys versus girls

BACKGROUND

Increasing evidence suggests a close association between early sexual maturation (SM) and obesity in girls and female adults. Earlier maturing girls are more likely to be obese than nonearly maturers. However, limited research has been conducted in boys.

OBJECTIVE

To examine the influence of early SM on fatness in boys and compare it with girls, and to test the hypothesis that the associations differ by gender because of the differences in growth and SM patterns in boys and girls.

STUDY DESIGN

Cross-sectional study.

SUBJECTS

One thousand five hundred one girls and 1520 boys (aged 8-14 years) who participated in the Third National Health and Nutrition Examination Survey survey (1988-1994) and had complete anthropometry (weight, height, skinfold thickness) and SM data.

METHODS

Based on each individual's age and SM status (Tanner stages: genitalia stages for boys and breast stages for girls), the subjects were classified as: 1) early maturers (those who reached a certain Tanner stage earlier than the median age for that stage), and 2) the others (average and later maturers). Overweight was defined as a body mass index (BMI) > or =85th percentile, and obesity > or =95th percentile. Logistic regression analysis was to test how early maturation affected the risks for overweight and obese. Using multiple linear regression models, the associations between fatness (BMI and skinfold thickness) and SM were systematically examined. Covariates including age, ethnicity, residence, family income, energy intake, and physical activity were adjusted.

RESULTS

Early SM was positively associated with overweight and obesity in girls, but the associations were reverse for boys. The prevalence of overweight in early maturers versus the others was 22.6% versus 31.6% in boys and 34.4% versus 23.2% in girls; the figures for obesity were 6.7% versus 14.8% and 15.6% versus 8.1%, respectively. Odd ratios and 95% confidence intervals for obesity were 0.4 (0.2, 0.8) for boys and 2.0 (1.1, 3.5) for girls, and covariates were adjusted. Most significant differences in overweight and obesity among ethnic groups disappeared after controlling for SM. Fatness (BMI and skinfold thickness) was associated with SM stages and with early maturation in boys and girls, but the associations were in opposite directions. Compared with their counterparts, early maturing boys were thinner, whereas early maturing girls were fatter.

CONCLUSIONS

Obesity is associated with sexual maturation in both boys and girls, but the association differs. There is positive association in girls, but a negative one in boys. Maturation status should be taken into consideration when assessing child and adolescent obesity.

Impact of timing of pubertal maturation on growth in black and white female adolescents: The National Heart, Lung, and Blood Institute Growth and Health Study

OBJECTIVES

To evaluate the impact of early, mid-onset, and late maturation, as assessed by timing of menarche, on height, height velocity, weight, body mass index, and sum of skinfolds in a group of white and black girls.

STUDY DESIGN

The Growth and Health Study recruited 9- and 10-year-old girls from Richmond, California, Cincinnati, Ohio, and Washington, DC. There were 616 white and 539 black participants recruited at age 9 and 550 white and 674 black participants recruited at age 10. Participants were seen annually for 10 visits. Longitudinal regression models were used to test for differences in each growth measure by timing of menarche across all ages and to determine whether these differences change with age.

RESULTS

Mean age at menarche among white participants was 12.7 years, and among black participants, 12.0 years. According to race-specific 20th and 80th percentiles, early maturers were tallest at early ages and shortest after adult stature had been attained. Peak height velocity and post-menarche increment in stature were greatest in early maturers and least in late maturers. Weight was greatest in early and least in late maturers, as was body mass index. Sum of skinfolds was also greatest in early and least in late maturers. There was no impact of timing of maturation on two common measures of regional fat distribution.

CONCLUSIONS

Girls who matured early were shorter in early adulthood, despite having greater peak height velocity and post-menarchal increment in height. Throughout puberty, early maturers had greater ponderosity and adiposity, although there was no association with regional distribution of fat.

Maturational timing and overweight prevalence in US adolescent girls

OBJECTIVES

This study examined the relation of age at menarche to overweight in US adolescent girls.

METHODS

Effects of age at menarche and race/ethnicity on overweight were estimated via logistic regression, after adjustment for sociodemographic characteristics, in a sample of 6507 Hispanic, Black, White, and Asian American girls who participated in wave 2 of the National Longitudinal Study of Adolescent Health.

RESULTS

Overweight prevalence rates were significantly higher in early maturing adolescents of all racial/ethnic groups but highest (57.5%) among early maturing Black girls. Early maturation nearly doubled the odds of being overweight (body mass index at or above the 85th percentile).

CONCLUSIONS

Greater public health attention should be focused on the high prevalence of overweight, particularly among minority female adolescents.

How does maturity adjustment influence the estimates of overweight prevalence in adolescents from different countries using an international reference?

OBJECTIVE

To investigate the effect of adjusting for differences in timing of maturation when assessing overweight prevalence among adolescents in different populations by using an international reference recommended by the WHO.

DESIGN

Cross-sectional, comparative study in three large samples from China, Russia and the United States.

SUBJECTS

A total of 2014 American, 1316 Chinese and 744 Russian non-pregnant adolescent girls aged 10-18 y.

MEASUREMENTS

Data on body weight, height, menarcheal status and age at menarche (AAM) were collected. Overweight was defined as age-sex-specific body mass index (BMI) greater than the 85th percentiles from the US NHANES I data (collected in 1971-1974), which is recommended by the WHO for international use. Maturity adjustments were made using population differences in median age at menarche (MAM), calculated using the status quo method. MAM was 12.8 in the WHO reference population, 13.7 in China, 13.2 in Russia, and 12.6 in the US (NHANES III data). Maturation age-matched BMI cut-offs were used to compute the adjusted prevalence. We also compared population-adjusted results with individually adjusted results in post-menarcheal American girls (based on each girl's AAM) and in pre-menarcheal girls (based on breast stage).

RESULTS

Maturity adjustment increased the estimated prevalence of overweight in China and Russia where girls mature later than the reference population, and decreased it in the NHANES III sample. The unadjusted and adjusted prevalence was 3.5 vs 4.9% in the China sample, 8.3 vs 9.7% in Russia, and 29.2 vs 28.0% in the US. The adjustment had a greater effect in younger adolescent girls (10-13 y) than in older girls (14-18 y). In general, we found a good agreement between the population and individual adjustments. Viewing the individual adjustment as a 'gold standard', the population method has a high sensitivity and specificity.

CONCLUSION

This is the first study to assess WHO recommendations for maturation adjustment when estimating overweight prevalence in different countries. While the overall effects of adjustment are small, maturation status should be considered, particularly when assessing young adolescents, and populations with markedly different timing of maturation relative to the international reference. Population-based adjustment is useful and practical in situations where individual maturity data are not available.

Familial resemblance for the age at menarche in Basque population

A cross-sectional sample from Biscay province (Basque Country, Spain) composed of 296 subjects from 143 nuclear families was analysed. The aim of this research was to study familial resemblance for the age at menarche and to investigate the influence that BMI, fatness and several socio-familial variables have on the menarcheal age. The influence of these variables on the degree of similarity of mother-daughter and sister-sister pairs for the age at onset of menstruation will be determined. Mean ages at menarche of mothers estimated by retrospective methodology (12.88 years, SD = 1.57) and daughters assessed by probit analysis (12.34 years. SD= 1.00) showed no statistically significant differences. Mother-daughter and sister-sister correlations increased after controlling for BMI, fatness and several socio-familial variables (0.25 vs 0.36 and 0.28 vs 0.44, respectively). The results revealed the importance of BMI, fatness, socio-economic level and the number of people living together in the household on menarcheal age and on the estimation of correlations. However, no influence from sibship size (possibly because this variable is a part of the people living together in the household) nor from birth order of the subjects was observed.

Age at spermarche and comparison of growth and performance of pre- and post-spermarcheal Chinese boys

The prevalence of first ejaculation emission (spermarche) in Chinese Han boys in 1995 was considered. The subjects were 86,744 Han boys 9 through 18 years randomly selected from 28 provinces. Median spermarcheal ages (MSAs) were 14.4 and 14.6 years for urban and rural boys, respectively, and 14.3, 14.6, and 14.7 years for the boys of 1st, 2nd, and 3rd socioeconomic classes, respectively. Two environmental factors, ecological and socioeconomic, had strong influence upon MSAs. Eight indicators of somatic growth and motor ability were compared between pre- and post-spermarcheal boys of the same age. Post-spermarcheal boys were advanced in body size, shape, and physiological function during early and middle puberty, but most of the difference disappeared by 16 years. Pre-spermarcheal boys in a given age group were more linear and had more potential for increasing leg length into late adolescence. Within an age group, post-spermarcheal boys had advanced performances in several tasks requiring endurance, strength, and power around the age of maximum growth, 13-15 years. At older ages, the groups did not differ.

Timing and magnitude of peak height velocity and peak tissue velocities for early, average, and late maturing boys and girls

Height, weight, and tissue accrual were determined in 60 male and 53 female adolescents measured annually over six years using standard anthropometry and dual-energy X-ray absorptiometry (DXA). Annual velocities were derived, and the ages and magnitudes of peak height and peak tissue velocities were determined using a cubic spline fit to individual data. Individuals were rank ordered on the basis of sex and age at peak height velocity (PHV) and then divided into quartiles: early (lowest quartile), average (middle two quartiles), and late (highest quartile) maturers. Sex- and maturity-related comparisons in ages and magnitudes of peak height and peak tissue velocities were made. Males reached peak velocities significantly later than females for all tissues and had significantly greater magnitudes at peak. The age at PHV was negatively correlated with the magnitude of PHV in both sexes. At a similar maturity point (age at PHV) there were no differences in weight or fat mass among maturity groups in both sexes. Late maturing males, however, accrued more bone mineral and lean mass and were taller at the age of PHV compared to early maturers. Thus, maturational status (early, average, or late maturity) as indicated by age at PHV is inversely related to the magnitude of PHV in both sexes. At a similar maturational point there are no differences between early and late maturers for weight and fat mass in boys and girls.

Quality of early family relationships and individual differences in the timing of pubertal maturation in girls: a longitudinal test of an evolutionary model

In an 8-year prospective study of 173 girls and their families, the authors tested predictions from J. Belsky, L. Steinberg, and P. Draper's (1991) evolutionary model of individual differences in pubertal timing. This model suggests that more negative-coercive (or less positive-harmonious) family relationships in early childhood provoke earlier reproductive development in adolescence. Consistent with the model, fathers' presence in the home, more time spent by fathers in child care, greater supportiveness in the parental dyad, more father-daughter affection, and more mother-daughter affection, as assessed prior to kindergarten, each predicted later pubertal timing by daughters in 7th grade. The positive dimension of family relationships, rather than the negative dimension, accounted for these relations. In total, the quality of fathers' investment in the family emerged as the most important feature of the proximal family environment relative to daughters' pubertal timing.

Impact of the age at menarche on adult body composition in healthy pre- and postmenopausal women

The present study focuses on the impact of age at menarche on body composition development during adulthood. With 459 healthy middle-class women between 18 and 67 years (x = 41.5) the association between age at menarche and body composition was tested. Body composition, described by absolute and relative amount of fat mass, lean body mass, and bone mass, was estimated by means of dual energy x-ray absorptiometry. In order to exclude the influence of the menopausal transition on body composition, pre- and postmenopausal females were examined separately. The absolute amount of body fat was significantly lower within the group of women whose menarche occurred later. However, postmenopausal females exhibit less significant relations between the two trait systems than premenopausal women. This may be due to the impact of menopausal transition which affected the hormone levels and body composition development independently from the adolescent hormonal transition. While in both proband groups the quantitative amount of body fat was significantly related to menarcheal age, a significant relation between menarcheal age and adult body fat distribution could not be verified.

Family size and age at menarche in athletes

The association between family size and age at menarche was evaluated in 370 university athletes representing seven sports, 291 white and 79 black. Age at menarche, number of children in the family (family size), and birth order were collected retrospectively by questionnaire with a follow-up interview if necessary. The effect of family size on menarche was estimated with linear regression and multiple regression. For each additional sibling in the family-age at menarche was later by 0.17 yr in white athletes, 0.21 yr in black athletes, and 0.16 yr in the total sample (about 2.0-2.5 months). The slopes for white (beta = 0.167) and black (beta = 0.208) athletes did not differ significantly. Controlling for the effects of birth order significantly increased the family size effect in white athletes (beta = 0.221), but not in black athletes (beta = 0.203) or in the total sample (beta = 0.164). The slopes for white and black athletes, after controlling for birth order, also did not significantly differ. Thus, after controlling for birth order, menarche was later by 0.16-0.22 yr (about 2.0-2.6 months) for each additional sibling in the family, which was within the range of family size effects observed in samples of nonathletes and athletes. The family size effect also persists after controlling for maternal age at menarche in a subsample of 134 athletes, thus implying an independent effect of family size. Later ages at menarche observed in athletes may thus be due in part to larger family sizes.

Determinants of resting energy expenditure in young black girls and young white girls

OBJECTIVE

To identify determinants of resting energy expenditure (REE) in black girls and white girls and to evaluate racial differences in REE.

STUDY DESIGN

Cross-sectional study of 98 girls (47 black and 51 white girls), ages 6 to 16 years.

METHODS

Determinations of lean body mass, fat mass, and bone mass were made by dual-energy x-ray absorptiometry. Measurements of REE were made with the DeltaTrac metabolic monitor. Subjects fasted at least 3 hours before testing, had rested 30 minutes before the test, and had not engaged in strenuous activity for the previous 12 hours. Pubertal maturation was assessed with a three-stage scoring method: (1) prepubertal, (2) pubertal, but premenarcheal, and (3) postmenarcheal.

RESULTS

There were no significant differences in height, weight, lean body mass, or fat mass between the black and white subjects. Racial differences in total REE were also not significant, but REE standardized by weight was significantly greater in white girls (40.3 kcal/day) compared with black girls (35.5 kcal/day) (p = 0.001). Resting energy expenditure was positively and significantly correlated with all measures of body composition. Multiple regression analysis identified lean body mass, sexual maturation, and race as significant main effects. After controlling for lean body mass and maturation, black girls had significantly lower REE. The race-maturation interaction was of borderline significance (p = 0.09); prepubertal black girls had significantly lower REE (1156 kcal/day) than prepubertal white girls (1399 kcal/day), but racial differences in stages 2 and 3 were not statistically significant.

CONCLUSION

Lean body mass, maturation, and race are significant determinants of REE. Resting energy expenditure is significantly lower in black than white girls in the prepubertal stage. The cause of this racial difference in REE is not known; it is not explained by differences in anthropometric variables. Racial differences in REE could explain in part the earlier onset of puberty in black girls compared with white girls and could be a factor in the difference in obesity in black and white women.

Sexual maturation and racial differences in blood pressure in girls: the National Heart, Lung, and Blood Institute Growth and Health Study

OBJECTIVE

To evaluate racial differences in blood pressure in girls aged 9 to 10 years in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS) and to evaluate the extent to which racial differences in blood pressure are explained by other factors, including sexual maturation and body size.

METHODS

The NGHS enrolled 539 black and 616 white girls aged 9 years, and 674 black and 550 white girls aged 10 years. Racial differences in blood pressure were examined. Relationships of stage of sexual maturation, height, and skinfold thickness with systolic and diastolic blood pressure were evaluated by multiple regression analysis.

RESULTS

The black girls had significantly higher systolic (102.0 +/- 8.90 vs 100.5 +/- 9.42 mm Hg, p <0.001) and diastolic (58.0 +/- 12.0 vs 56.5 +/- 12.51 mm Hg, p <0.01) blood pressures than the white girls. The black girls were also more advanced in sexual maturation and were taller (142.9 +/- 7.94 vs 139.6 +/- 7.05, p <0.001) and heavier (39.6 +/- 11.24 vs 35.3 +/- 8.73 kg, p <0.001) than the white girls. Both systolic and diastolic blood pressure were significantly correlated with level of maturation, height, weight, and sum of skinfolds. Stage of maturation was found to account for the difference in blood pressure between black girls and white girls. In a multiple regression analysis, controlling for height (for diastolic blood pressure) and for both height and sum of skinfolds (for systolic blood pressure) eliminated the effects of race and stage of maturation on blood pressure.

CONCLUSION

Racial differences in blood pressure were observed for 9- and 10-year-old girls and are explained by the fact that black girls were more mature than white girls. The effect of sexual maturation on blood pressure appears to operate through height and body fat. The effect of obesity may be more important for systolic than for diastolic blood pressure. Continuation of racial differences in blood pressure may result in a higher prevalence of hypertension for black women.

Menarche age, fatness, and fat distribution in Hawaiian adolescents

Menarche age was assessed in 93 adolescent females in a sample of public schools in East Hawaii. Native Hawaiian girls had significantly lower reported age at menarche than non-Hawaiian classmates. Age at menarche was significantly correlated with total fatness as measured by the sum of six skinfolds in girls who had reached menarche at least 2 years previous to measurement. When fatness was controlled in comparisons, the ethnic differences were not significant. Fat distribution, independent of fatness, was also significantly related to age at menarche. Socioeconomic, cultural, and admixture variables were not significantly related to age at menarche. Adiposity appears to be both a cause and a consequence of early age at menarche, with the relationship dependent on the elapsed time between menarche and measurement. This suggests that studies relating body composition to age at menarche must carefully control for the time interval between measurement and the date of menarche.

Age at menarche: Relationships to socioeconomic status, growth rate in stature and weight, and skeletal and sexual maturation

A sample of 114 girls from low-middle and highest socioeconomic levels of Istanbul were followed at 6-month intervals for 7-9 years during adolescence. Results pertaining to age of menarche and its relationship to growth and maturation are presented. No significant difference was found for the occurrence of menarche in relation to season. The age of menarche was 6.6 months earlier in daughters compared to their mothers, but the variation between mothers and daughters was great. In the lower socioeconimic class, age of menarche was significantly later, 12.5 years in the high and 13.4 years in the lower class. Later menarche in the lower class was related to lower rates of growth in stature and weight, and of skeletal and sexual maturation. There was no significant correlation between age at menarche and stature and weight attained at menarche. Those with a faster rate of growth reached menarche early and the height velocity continued to be faster. The median stages of secondary sexual characteristics at menarche were 4 for breast and pubic hair, and 3 for axillary hair. The stage of development at menarche did not differ significantly with age of menarche and social class. Menarche occurred 2.4 years after the appearance of pubic hair, 2.0 years after the appearance of the breast bud, and 1.4 years after the appearance of axillary hair, and the ages at which the secondary sexual characters appeared correlated significantly with the age of menarche. Skeletal age at menarche was 13.0 ± 0.69 years. Age of menarche correlated best with the age at which fusion of the second and first distal phalanges occurred. The percentage of adult height attained at menarche correlated significantly with the age of menarche. Regression equations and standard errors are presented to aid in the prediction of the age at menarche from other variables related to menarche.

The timing of sexual maturation in a group of US white youths

The purpose of this study was to present US reference data for chronological ages at which stages of sexual maturation were observed in white youths. Recent serial data from 78 males and 67 females were analyzed to obtain descriptive statistics for the ages at onset of these stages and the mean ages at which the stages are observed. These reference data should assist the identification of white US youths who are maturing at rapid or slow rates and the interpretation of growth data.

Sexual maturation and obesity in 9- and 10-year-old black and white girls: the National Heart, Lung, and Blood Institute Growth and Health Study

OBJECTIVE

To assess the relationship between pubertal maturation and obesity in 9- and 10-year-old black and white girls.

METHOD

Cross-sectional analysis of cohort baseline data.

SUBJECTS

A cohort of 2379 girls recruited from selected schools in Richmond, Calif., and greater Cincinnati, Ohio, and from the membership rolls of a prepaid group practice in greater Washington, D.C.

RESULTS

Sixty-four percent of black girls had begun pubertal maturation compared with 33% of white girls. In prepubertal girls, racial differences in height, weight, body mass index (kilograms per square meter) and skin-fold thickness were not significant. Within each race, onset of pubertal maturation was associated with greater height, weight, body mass index, and skin-fold measurements. Within 9-year-old girls who had begun pubertal maturation but not reached menarche, black girls were taller and heavier than white girls. Among pubertal but premenarcheal 10-year-old subjects, black girls were taller and heavier and had greater body mass index and subscapular skin-fold values. After analyses were adjusted for pubertal maturation stage by means of pubic hair development, 10-year-old pubertal black girls remained taller and heavier, but racial differences in body mass index and the sum of skin-fold measurements ceased to be significant.

CONCLUSIONS

These findings suggest that the initiation of racial differences in obesity are related, at least temporally, to pubertal maturation.