Early life household intactness and timing of pubertal onset in girls: a prospective cohort study.

BACKGROUND: Girls who experience early-life familial stress may have heightened risk of early puberty, which has adverse implications for adolescent and adult health. We assessed the association between household intactness and pubertal onset using a racially/ethnically diverse cohort of girls from Northern California. METHODS: A prospective cohort study of 26,044 girls born in 2003-10. Girls living with both parents from birth up to 6 years were considered to come from "intact" households while others constituted "non-intact" households. Pubertal development was measured using pediatrician-assessed Tanner staging for breast and pubic hair. Pubertal onset was defined as the transition from Tanner Stage 1 to 2+ for breast (thelarche) and pubic hair (pubarche). Menarche data was collected from routine well-child questionnaires. Weibull regression models accommodating left, right, and interval censoring were used to determine risk of earlier thelarche and pubarche, and logistic regressions were used to assess the risk of early menarche (age < 12). RESULTS: Girls exposed to non-intact households before age 2 years were at increased risk for earlier thelarche and pubarche with significant effect modification by race/ethnicity, compared with girls from intact households. The associations were strongest among Black girls (adjusted hazard ratio [HR]: 1.60, 95% confidence interval [CI]: 1.29,1.98; HR: 1.42, 95%CI: 1.15,1.77 for thelarche and pubarche, respectively). There were no significant associations among Asian/Pacific Islanders. Girls who lived in non-intact households before age 2 years were also at increased risk for earlier menarche, but without race/ethnic interaction. Adjustment for prepubertal obesity did not change these associations. Associations between living in non-intact households after age 2 years and early puberty were weaker but still significant. CONCLUSIONS: Exposure to a non-intact household early in life may increase the risk of early puberty in girls. Future psychosocial interventions focused on improving family cohesiveness and efforts to reduce childhood stress among families that are non-intact may mitigate these negative associations, thereby preventing future adverse health effects of early puberty and health disparities.

Girls' Sleep Trajectories Across the Pubertal Transition: Emerging Racial/Ethnic Differences.

PURPOSE: This study aims to examine the longitudinal association between puberty and sleep in a diverse sample of girls and explore racial/ethnic differences in this association. METHODS: Using latent growth curve modeling, the present study measured pubertal development (timing and rate) and sleep (wake time and bedtime) in 1,239 socioeconomically and ethnically diverse girls starting when they were 6-8 years old and followed longitudinally for up to 8 years. Pubertal assessment was conducted annually in clinic by physical examination, classified by sexual maturation stage for breast and pubic hair development by trained raters. RESULTS: In line with previous research, black girls had the earliest pubertal development, followed by Hispanic, white, and Asian girls. Black girls, on average, reported significantly shorter sleep duration than Hispanic (ß = -.20, p < .001), Asian (ß = -.29, p = .002), and white (ß = -.35, p < .001) girls. In a series of dual-process models, we found that early pubertal timing predicted shorter sleep duration for early-maturing black girls (breast development: ß = .13, p = .005; pubic hair development: ß = .14, p = .012). There was no evidence of any association between pubertal rate and sleep. All models controlled for family socioeconomic status and body mass index. CONCLUSION: Sleep is essential for many aspects of youth development, including emotional, cognitive, and physical functioning. Developmental changes associated with puberty may put some early maturing girls at risk of shorter sleep duration in adolescence and exacerbate racial/ethnic disparities in health and well-being.

Breastfeeding versus formula-feeding and girls' pubertal development.

To examine the association of breastfeeding or its duration with timing of girls' pubertal onset, and the role of BMI as a mediator in these associations. A population of 1,237 socio-economically and ethnically diverse girls, ages 6-8 years, was recruited across three geographic locations (New York City, Cincinnati, and the San Francisco Bay Area) in a prospective study of predictors of pubertal maturation. Breastfeeding practices were assessed using self-administered questionnaire/interview with the primary caregiver. Girls were seen on at least annual basis to assess breast and pubic hair development. The association of breastfeeding with pubertal timing was estimated using parametric survival analysis while adjusting for body mass index, ethnicity, birth-weight, mother's education, mother's menarcheal age, and family income. Compared to formula fed girls, those who were mixed-fed or predominantly breastfed showed later onset of breast development [hazard ratios 0.90 (95 % CI 0.75, 1.09) and 0.74 (95 % CI 0.59, 0.94), respectively]. Duration of breastfeeding was also directly associated with age at onset of breast development (p trend = 0.008). Associations between breastfeeding and pubic hair onset were not significant. In stratified analysis, the association of breastfeeding and later breast onset was seen in Cincinnati girls only. The association between breast feeding and pubertal onset varied by study site. More research is needed about the environments within which breastfeeding takes place in order to better understand whether infant feeding practices are a potentially modifiable risk factor that may influence age at onset of breast development and subsequent risk for disease in adulthood.

Longitudinal effects of parental, child and neighborhood factors on moderate-vigorous physical activity and sedentary time in Latino children.

BACKGROUND: Moderate-vigorous physical activity (%MVPA) confers beneficial effects on child musculoskeletal health, cardiovascular fitness, and psychosocial well-being; in contrast, sedentary time (%SED) is emerging as a risk factor for health. This study aimed to identify parental, child and neighborhood factors influencing longitudinal assessments of body mass index (BMI) and activity patterns among Latino children, and to estimate lagged and cross-lagged effects between child BMI, %MVPA and %SED. METHODS: A longitudinal design with assessments at baseline, 1 and 2 years follow-up (FU) was used to evaluate the effects of maternal and paternal factors (BMI, age, education level, acculturation, household income and household size), child factors (gender, age, BMI, pubertal status) and neighborhood factors (disorder, victimization) on child BMI, %MVPA and %SED, expressed as a percent of awake time, in 282 Latino children ages 8-10 y and their parents. This study was restricted to families with a mother and biological father or father figure in the child's life. RESULTS: Across time, total daily accelerometer counts (p = 0.04) and steps decreased (p = 0.0001), %SED increased (p = 0.0001), and %MVPA decreased (p = 0.02). Moderate lagged effects or tracking was seen for %MVPA and %SED (p = 0.001). %MVPA varied by gender (5.5% higher in boys than girls, p = 0.0001); child age (-0.4% per year, p = 0.03), and child BMI in boys only (-0.22%, p = 0.0002). Negative effects of paternal age, maternal education and maternal changes in BMI on %MVPA also were seen. %SED increased with child age (2.5% higher per year, p = 0.0001). Positive effects of paternal acculturation, maternal change in BMI, paternal age, and negative effects of household size on %SED were observed. A cross-lagged positive effect of BMI at FU1 on %SED at FU2 was observed for boys and girls (p = 0.03). Neighborhood disorder and victimization were not significant predictors of child BMI, %MVPA or %SED. CONCLUSION: The major child determinants of physical activity (age, gender and BMI) and minor parental influences (maternal BMI and education, paternal age and acculturation) should be considered in designing interventions to promote %MVPA and reduce %SED among Latino children as they approach adolescence.

Lipid screening in children and adolescents in community practice: 2007 to 2010.

BACKGROUND: Integrated guidelines on cardiovascular health and risk reduction in children issued in 2011 newly recommended universal screening for dyslipidemia in children at 9 to 11 years and 17 to 21 years. METHODS AND RESULTS: We determined the frequency and results of lipid testing in 301 080 children and adolescents aged 3 to 19 enrolled in 3 large US health systems in 2007 to 2010 before the 2011 guidelines were issued. Overall, 9.8% of the study population was tested for lipids. The proportion tested varied by body mass index percentile (5.9% of normal weight, 10.8% of overweight, and 26.9% of obese children) and age (8.9% of 9- to 11-year olds and 24.3% of 17- to 19-year olds). In normal weight individuals, 2.8% of 9- to 11-year olds and 22.0% of 17- to 19-year olds were tested. In multivariable models, age and body mass index category remained strongly associated with lipid testing. Sex, race, ethnicity, and blood pressure were weakly associated with testing. Abnormal lipid levels were found in 8.6% for total cholesterol, 22.5% for high-density lipoprotein-cholesterol, 12.0% for non-high-density lipoprotein-cholesterol, 8.0% for low-density lipoprotein-cholesterol, and 21% for triglycerides (age, 10-19 years). There was a strong and graded association of abnormal lipid levels with body mass index, particularly for high-density lipoprotein-cholesterol and triglycerides (2- to 6-fold higher odds ratio in obese when compared with that in normal weight children). CONCLUSIONS: Lipid screening was uncommon in 9- to 11-year olds and was performed in a minority of 17- to 19-year olds during 2007 to 2010. These data serve as a benchmark for assessing change in practice patterns after the new recommendations for pediatric lipid screening and management.

Father absence, body mass index, and pubertal timing in girls: differential effects by family income and ethnicity.

PURPOSE: Numerous studies show associations between father absence and girls' early puberty. However, most research has been retrospective, focused on menarche, and failed to consider body mass index (BMI), ethnicity, and income in the analyses. This study resolves these scientific gaps. METHODS: This was a prospective study of 444 girls aged 6-8 years and their caregivers (96% mothers). Data were collected annually in clinic, including weight, height, and Tanner stage for breast and pubic hair. Caregivers reported on father absence and demographics. This report focuses on the assessment of father absence at baseline and 2 years of follow-up for pubertal outcomes. Cox proportional hazards regression models were used to test whether father absence at baseline predicted pubertal onset by follow-up visit 2. BMI was assumed to be in the causal pathway. Differences by ethnicity and income were examined. RESULTS: Income and ethnicity moderated associations between father absence and pubertal onset when adjusting for BMI. Father absence predicted earlier onset of breast development only in higher-income families and onset of pubic hair development only in higher-income African Americans families. BMI was not related to father absence and therefore was not in the causal pathway. CONCLUSION: Among girls from higher-income families, father absence was linked to earlier puberty. This was particularly true for African Americans in terms of pubic hair development. These effects are not explained by body weight. Future research is needed to identify social and biophysiological mechanisms through which father absence, ethnicity, and income affect the pubertal onset.

Pubertal assessment method and baseline characteristics in a mixed longitudinal study of girls.

OBJECTIVES: The objective of this study was to describe the assessment methods and maturation status for a multisite cohort of girls at baseline recruitment and at ages 7 and 8 years. METHODS: The method for pubertal maturation staging was developed collaboratively across 3 sites. Girls at ages 6 to 8 years were recruited at 3 sites: East Harlem, New York; greater Cincinnati metropolitan area; and San Francisco Bay area, California. Baseline characteristics were obtained through interviews with caregivers and anthropometric measurements by trained examiners; breast stage 2 was defined as onset of pubertal maturation. The kappa statistic was used to evaluate agreement between master trainers and examiners. Logistic regression models were used to identify factors that are associated with pubertal maturation and linear regression models to examine factors that are associated with height velocity. RESULTS: The baseline cohort included 1239 girls. The proportion of girls who had attained breast stage 2 varied by age, race/ethnicity, BMI percentile, and site. At 7 years, 10.4% of white, 23.4% of black non-Hispanic, and 14.9% of Hispanic girls had attained breast stage>or=2; at 8 years, 18.3%, 42.9%, and 30.9%, respectively, had attained breast stage>or=2. The prime determinant of height velocity was pubertal status. CONCLUSIONS: In this multisite study, there was substantial agreement regarding pubertal staging between examiners across sites. The proportion of girls who had breast development at ages 7 and 8 years, particularly among white girls, is greater than that reported from studies of girls who were born 10 to 30 years earlier.