Comparing physical activity questionnaires for youth: seasonal vs annual format

Associations Between Phenotypes of Childhood and Adolescent Obesity and Incident Hypertension in Young Adulthood

Objectives

We investigated whether empirically derived childhood obesity phenotypes were differentially associated with risk of hypertension in young adulthood, and whether these associations differed by sex.

Methods

Data came from 11,404 participants in the Growing Up Today Study, a prospective cohort study in the US established in 1996. We used a childhood obesity phenotype variable that was previously empirically derived using latent class analysis. The childhood obesity phenotypes included an early puberty phenotype (females only), a mothers with obesity phenotype, a high weight concerns phenotype, and a mixed phenotype. Participants without overweight or obesity in childhood or adolescence were the reference group. We then used logistic regression models with generalized estimating equations to examine associations of childhood obesity phenotypes with incident hypertension between ages 20-35 years. All analyses were stratified by sex.

Results

Among females, participants in all of the empirically derived childhood obesity phenotypes were more likely than their peers without childhood overweight/obesity to develop hypertension in young adulthood (early puberty subtype odds ratio (OR) = 2.52; 95% confidence interval (CI) = 1.75, 3.62; mothers with obesity (MO) subtype OR = 2.98; 95% CI = 1.93, 4.59; high weight concerns (WC) subtype OR = 2.33; 95% CI = 1.65, 3.28; mixed subtype OR = 1.66; 95% CI = 1.25, 2.20). Among males, the childhood obesity phenotypes were associated with a higher risk of developing hypertension, although males in the MO (OR = 2.65; 95% CI = 1.82, 3.87) and WC phenotypes (OR = 3.52; 95% CI = 2.38, 5.20) had a greater risk of developing hypertension than the mixed subtype (OR = 1.51; 95% CI = 1.23, 1.86) (p = 0.004).

Conclusion

Risk for incident hypertension in young adulthood varied by childhood obesity phenotypes, as well as by biological sex. If replicated, these results may suggest that increased surveillance of specific childhood obesity phenotypes might help in targeting those at highest risk for hypertension.

A Youth Health Leadership Program: Feasibility and Initial Outcomes

This study determined the feasibility (attendance, participation and completion) and initial outcomes (food consumption, food acquisition, physical activity and leadership) of a community-based youth health leadership (YHL) program. YHL was developed as a part of a larger childhood obesity prevention coalition in a medium-sized community in North Florida using community-based participatory research approaches. The theory-driven 6-week program included content sessions, application rotation, and health campaign. Data were collected from youth participants (n = 36) and a purposive comparison group (n = 29) via self-administered questionnaire and project records in the first three years of YHL. Feasibility outcomes show that the majority of program participants attended and participated. Completion rates ranged from 61.5% in year one to 100% in years two and three. Significant differences in treatment and comparison groups were noted in frequency of fruit consumption (p < 0.001) and physical activity (p < 0.002). However, there were no clear patterns of improvements for the treatment group. Trends in the data showed that the consumption of foods high in fat, sugar and sodium decreased slightly for the treatment group but increased or remained the same for the comparison group. The leadership outcomes for youth participants show that those reached are furthering their education, participating in activities such as internships, receiving honors, and garnering leadership achievements. This study suggests that a community-based youth health leadership model is feasible, but more work is needed to impact health behaviors. Future research directions are provided.

US adolescents at risk for not meeting physical activity recommendations by season

BACKGROUND

We sought to identify regional and seasonal variation in not meeting physical activity (PA) recommendations of ≥60 min a day of moderate-to-vigorous PA (MVPA) and 3 h of vigorous PA per week (VPA) in a longitudinal cohort of United States (US) adolescents.

METHODS

Participants in the Growing Up Today Study 2, a prospective study of 10,918 adolescents, self-reported season-specific weekly hours of MVPA and VPA from 2004 through 2011. To assess variation in PA by climate, we grouped the contiguous US into nine climatically consistent geographic regions. We also examined MVPA and VPA by season, sex, ethnicity, weight status, and age group.

RESULTS

The majority (85%) of adolescents did not meet the MVPA recommendation, and 91% did not meet the VPA recommendation, for one or more seasons over the four study years. Across all climate regions, adolescents were two times more likely to not meet the MVPA recommendation during the winter compared to summer (odds ratio 2.02, 95% confidence interval: 1.96-2.08).

CONCLUSION

Regardless of climate region, gender, ethnicity, or age group, adolescents were more likely not to meet MVPA or VPA recommendations in the winter than the summer. Adolescents may benefit from interventions aimed at increasing PA in the winter.

Seasonal Variations in Meeting Physical Activity Recommendations and Development of Overweight during Adolescence

BACKGROUND

Few longitudinal studies have examined seasonal variation in meeting physical activity (PA) recommendations in association with incident overweight among adolescents.

METHODS

We assessed self-reported, season-specific PA among 12,949 adolescents in two US cohorts (Growing Up Today Studies 1 and 2). We examined the relationship between the number of seasons per year that adolescents met the recommended amount of moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA), respectively, and the development of incident overweight at the next survey period. The sex-specific analyses controlled for follow-up time, survey month, age, race/ethnicity, sexual maturation, television viewing, region of the country, and intakes of sugar-sweetened beverages and fried foods away from home.

RESULTS

About one-third (34%) of adolescents met the MVPA recommendation of 60 minutes/day, and one-quarter (24%) the VPA recommendation of 3 hours/week, for four seasons of the baseline year. The risk of becoming overweight was 23% (95% confidence interval [CI]: 5%-45%) higher for girls who met the MVPA recommendation for 2 (vs. 4) seasons/year. The risk was similar for girls who met the recommendation for 1 (vs. 4) season/year (odds ratio = 1.23, 95% CI: 1.05-1.44). The number of seasons each year boys met the MVPA recommendation, or girls or boys met the VPA recommendation, was not associated with an increased risk of incident overweight.

CONCLUSIONS

Meeting the MVPA recommendation for 1 or 2 (vs. 4) seasons/year is related to higher risk of becoming overweight among adolescent girls but not boys. Interventions to increase PA levels each season may contribute to overweight prevention efforts among girls.

The ability of low-magnitude mechanical signals to normalize bone turnover in adolescents hospitalized for anorexia nervosa

We sought to determine whether low-magnitude mechanical stimulation (LMMS) normalizes bone turnover among adolescents hospitalized for anorexia nervosa (AN). Brief, daily LMMS prevents the decline in bone turnover typically seen during bed rest in AN. LMMS may have application for patients with AN in the inpatient setting to protect bone health.

INTRODUCTION

Malnourished adolescents with AN requiring medical hospitalization are at high risk for rapid reduction in skeletal quality. Even short-term bed rest can suppress normal patterns of bone turnover. We sought to determine whether LMMS normalizes bone turnover among adolescents hospitalized for complications of AN.

METHODS

In this randomized, double-blind trial, we prospectively enrolled adolescent females (n = 41) with AN, age 16.3 ± 1.9 years (mean ± SD) and BMI 15.6 ± 1.7 kg/m². Participants were randomized to stand on a platform delivering LMMS (0.3 g at 32-37 Hz) or placebo platform for 10 min/day for 5 days. Serum markers of bone formation [bone-specific alkaline phosphatase (BSAP)], turnover [osteocalcin (OC)], and bone resorption [serum C-telopeptides (CTx)] were measured. From a random coefficients model, we constructed estimates and confidence intervals for all outcomes.

RESULTS

BSAP decreased by 2.8% per day in the placebo arm (p = 0.03) but remained stable in the LMMS group (p = 0.51, p_diff = 0.04). CTx did not change with placebo (p = 0.56) but increased in the LMMS arm (+6.2% per day, p = 0.04; p_diff = 0.01). Serum OC did not change in either group (p > 0.70).

CONCLUSIONS

Bed rest during hospitalization for patients with AN is associated with a suppression of bone turnover, which may contribute to diminished bone quality. Brief, daily LMMS prevents a decline in bone turnover during bed rest in AN. Protocols prescribing strict bed rest may not be appropriate for protecting bone health for these patients. LMMS may have application for these patients in the inpatient setting.

Aerobic Fitness Linked to Cortical Brain Development in Adolescent Males: Preliminary Findings Suggest a Possible Role of BDNF Genotype

Aerobic exercise has been shown to impact brain structure and cognition in children and adults. Exercise-induced activation of a growth protein known as brain derived neurotrophic factor (BDNF) is thought to contribute to such relationships. To date, however, no study has examined how aerobic fitness relates to cortical brain structure during development and if BDNF genotype moderates these relationships. Using structural magnetic resonance imaging (MRI) and FreeSurfer, the current study examined how aerobic fitness relates to volume, thickness, and surface area in 34 male adolescents, 15 to 18 years old. Moreover, we examined if the val66met BDNF genotype moderated these relationships. We hypothesized that aerobic fitness would relate to greater thickness and volumes in frontal, parietal, and motor regions, and that these relationships would be less robust in individuals carrying a Met allele, since this genotype leads to lower BDNF expression. We found that aerobic fitness positively related to right rostral middle frontal cortical volume in all adolescents. However, results also showed BDNF genotype moderated the relationship between aerobic fitness and bilateral medial precuneus surface area, with a positive relationship seen in individuals with the Val/Val allele, but no relationship detected in those adolescents carrying a Met allele. Lastly, using self-reported levels of aerobic activity, we found that higher-fit adolescents showed larger right medial pericalcarine, right cuneus and left precuneus surface areas as compared to their low-fit peers. Our findings suggest that aerobic fitness is linked to cortical brain development in male adolescents, and that more research is warranted to determine how an individual’s genes may influence these relationships.

Physical Activity Patterns Among Somali Adolescents in Minnesota

BACKGROUND

Little is known about the physical activity patterns of Somali adolescents. This study compared time spent in moderate-to-vigorous physical activity (MVPA) and participation in specific physical activities among Somali, other Non-Hispanic black and white adolescents.

METHODS

A subsample of 1,268 adolescents (mean age= 14.6) who completed surveys as part of the EAT 2010 (Eating and Activity in Teens) study was included in analyses. Gender-stratified linear and logistic regressions, controlling for body mass index and demographic characteristics, were conducted to estimate mean weekly hours of self-reported MVPA and mean weekly hours and prevalence of engagement in each of 26 physical activities assessed by ethnic/racial group.

RESULTS

Somali girls had lower mean MVPA hours than their peers; however, no differences were found for Somali boys. Involvement in most activities was similar for Somali and other groups, but some differences were observed. For example, Somali youth were more likely to play soccer than their same-sex other black peers (boys: 52.4% vs. 20.4%; girls: 34.6% vs. 14.6%; P < .05). Somali girls also engaged in more hours per week of soccer than their black or white peers.

CONCLUSIONS

Activities for which Somali youth indicated higher involvement may be particularly relevant for culturally-tailored physical activity programming.

Millennials at work: workplace environments of young adults and associations with weight-related health

BACKGROUND

The purpose of this study was to describe the workplace environments of young adults and examine associations with diet, physical activity (PA) and body mass index (BMI).

METHODS

Cross-sectional data were collected (2008-2009) from 1538 employed young adult participants in Project EAT (Eating and Activity among Teens and Young Adults), a diverse population-based sample. Survey measures assessed height, weight, diet, moderate-to-vigorous PA, transportation-related PA and perceptions of the workplace food and PA environments (eg, soda availability, coworker support). Healthful characteristics were summed to reflect overall workplace healthfulness. Modified Poisson regression analyses conducted in 2015 identified associations between workplace food and PA environments and diet, PA and BMI.

RESULTS

The healthfulness of workplace environments was suboptimal. Greater exposure to healthful workplace characteristics was related to more young adults engaged in favourable diet and PA behaviours and a lower prevalence obesity. For example, adjusted rates of obesity were 24% and 17% among those reporting low (≤1 characteristic) versus high (≥3 characteristics) exposure to healthful food environments, respectively (p<0.05). Workplace characteristics independently associated with weight-related outcomes included soda availability, proximity to a fast food outlet, living close to work and perceived ease of eating a healthy diet or being active at work.

CONCLUSIONS

A more healthful workplace environment overall, including physical attributes and perceived social norms, may contribute to more favourable weight-related behaviours and lower prevalence of obesity among young adults. Employer-initiated and community-initiated policies may represent one way to create healthier workplace environments for young adults.

Relationship between motor skills, participation in leisure activities and quality of life of children with Developmental Coordination Disorder: temporal aspects

The study examined the relationship between motor skills, participation in leisure activities and quality of life (QOL), within a temporal context (school year vs. summer vacation and school days vs. weekends). Parents of 22 children with Developmental Coordination Disorder (DCD) and of 55 typically developing children, aged 6-11, filled out two questionnaires relating to their children's participation in leisure activities (vigorous, moderate and sedentary) and QOL. The Movement Assessment Battery for Children-2 (MABC-2) was administered to their children. Results showed that among the children with DCD, balance scores positively correlated with participation in sedentary activities, and in both groups both balance and aiming and catching were related to the physical and school aspects of QOL. Furthermore, participation in vigorous activities in the summer was positively correlated with social and school QOL. In contrast, among typically developing children, participation in vigorous activities during the school year was negatively correlated with school QOL. Finally, in both groups, participation in sedentary activities during school days was negatively correlated with school QOL. These results suggest that the parents' perceptions of their children's QOL may be related to the level of activeness of the leisure activities but also to temporal aspects. Therefore, it is important that therapists and educators consider the temporal aspects, when consulting with parents and their children regarding participation in leisure activities.

Bone strength and structural deficits in children and adolescents with a distal forearm fracture resulting from mild trauma

Although distal forearm fractures (DFFs) are common during childhood and adolescence, it is unclear whether they reflect underlying skeletal deficits or are simply a consequence of the usual physical activities, and associated trauma, during growth. Therefore, we examined whether a recent DFF, resulting from mild or moderate trauma, is related to deficits in bone strength and cortical and trabecular bone macro- and microstructure compared with nonfracture controls. High-resolution peripheral quantitative computed tomography was used to assess micro-finite element-derived bone strength (ie, failure load) and to measure cortical and trabecular bone parameters at the distal radius and tibia in 115 boys and girls with a recent (<1 year) DFF and 108 nonfracture controls aged 8 to 15 years. Trauma levels (mild versus moderate) were assigned based on a validated classification scheme. Compared with sex-matched controls, boys and girls with a mild-trauma DFF (eg, fall from standing height) showed significant deficits at the distal radius in failure load (-13% and -11%, respectively; p < 0.05) and had higher ("worse") fall load-to-strength ratios (both +10%; p < 0.05 for boys and p = 0.06 for girls). In addition, boys and girls with a mild-trauma DFF had significant reductions in cortical area (-26% and -23%, respectively; p < 0.01) and cortical thickness (-14% and -13%, respectively; p < 0.01) compared with controls. The skeletal deficits in the mild-trauma DFF patients were generalized, as similar changes were present at the distal tibia. By contrast, both boys and girls with a moderate-trauma DFF (eg, fall from a bicycle) had virtually identical values for all of the measured bone parameters compared with controls. In conclusion, DFFs during growth have two distinct etiologies: those owing to underlying skeletal deficits leading to fractures with mild trauma versus those owing to more significant trauma in the setting of normal bone strength.

Changes in physical activity and sedentary behavior in a randomized trial of an internet-based versus workbook-based family intervention study

BACKGROUND

The America on the Move (AOM) Family Intervention Program has been shown to prevent excess weight gain in overweight children. Providing intervention materials via the internet would have the potential to reach more families but may increase sedentary behavior. The purpose was to evaluate whether delivering the AOM Family Intervention via the internet versus printed workbook would have a similar impact on sedentary behaviors in children.

METHODS

131 children (age 8-12) were randomized to receive the AOM Family Intervention via the internet or workbook for 12 weeks. Changes in objectively measured sedentary time and moderate-to vigorous physical activity (MVPA) as well as self-reported screen time were compared between groups.

RESULTS

There were no significant differences between groups in screen time, sedentary time, or MVPA at the end of the 12 week intervention. Families receiving the intervention via the internet were more likely to remain in the study (98% vs. 82%, P = .016).

CONCLUSIONS

Using the internet to deliver the lifestyle intervention did not increase sedentary behavior in children. Attrition rates were lower when the program was delivered by internet versus via printed materials. These results provide support for using the internet to deliver healthy lifestyle programs for children.

Physical activity and screen time in adolescents transitioning out of compulsory education: a prospective longitudinal study

BACKGROUND

Within the UK context, it is unclear whether physical activity and screen time changes between completing compulsory education and the period afterwards, and the factors associated with any change.

METHODS

A prospective population-based longitudinal design among adolescents (n = 2204 at baseline) was adopted. A self-report questionnaire was administered at baseline (final year of compulsory education) and follow-up (i.e. post compulsory education) to measure physical activity over the previous 7 days and screen time (weekday and weekend) in relation to recommended guidelines. Magnitude of change in physical activity and screen time and key influencing variables associated with changes were analysed.

RESULTS

For physical activity, there was a significant change in participants meeting guidelines at baseline but not meeting guidelines at follow-up with 81.0% not meeting guidelines at baseline and follow-up. For screen time, there was no significant change between baseline and follow-up, with 70.6% not meeting guidelines at baseline and follow-up. Gender was associated with the change in physical activity with a decline less likely in females.

CONCLUSIONS

Findings reinforce the importance of reducing physical inactivity and sedentary behaviour during this transition. Factors associated with changes in physical inactivity and sedentary behaviour need further investigation.

Seasonal variation in physical activity and sedentary time in different European regions. The HELENA study

This report aims (1) to examine the association between seasonality and physical activity (PA) and sedentary time in European adolescents and (2) to investigate whether this association was influenced by geographical location (Central-North versus South of Europe), which implies more or less extreme weather and daylight hours. Valid data on PA, sedentary time and seasonality were obtained in 2173 adolescents (1175 females; 12.5-17.5 years) included in this study. Physical activity and sedentary time were measured by accelerometers. ANCOVA was conducted to analyse the differences in PA and sedentary time across seasons. Results showed that girls had lower levels of moderate to vigorous PA (MVPA) and average PA, and spent more time in sedentary activities in winter compared with spring (all P < 0.05). Stratified analyses showed differences in PA and sedentary time between winter and spring in European girls from Central-North of Europe (P < 0.05 for sedentary time). There were no differences between PA and sedentary time across seasonality in boys. In conclusion, winter is related with less time spent in MVPA, lower average PA and higher time spent in sedentary activities in European adolescent girls, compared with spring. These differences seem to mainly occur in Central-North Europe.

An evaluation of questionnaires assessing physical activity levels in youth populations

The aim of this study was to revise and organize according to recall time based criteria, questionnaires created and validated to assess the level of physical activity in children and adolescents, with the intention of enabling their proper understanding and subsequent use by nurses and health care professionals. In order to determine the questionnaires' quality, their degree of reliability and validity was the main feature to be taken into account. Thirty-eight papers were retrieved and analyzed, 31 of which were aimed at designing and validating a questionnaire intended for physical activity (PA) level assessment in youth populations (four to 19 year olds). The most widely used questionnaires were those whose recall time spans from one to seven days. In general, all questionnaires were characterized by the use of pen-and-paper format and scarce utilization of new technologies. Based upon validity and reliability criteria, in order to assess PA level in children and adolescents, nurses should use the "Children's Leisure Activities Study Survey" and the "Flemish Physical Activity Computer Questionnaire", respectively. There is a need for the validation of these tools in other languages and cultures.

Evaluation of 2 self-report measures of physical activity with accelerometry in young adults

BACKGROUND

The purpose of this paper is to evaluate self-reported physical activity of young adults using 1-week and 1-year recall measures with an accelerometer as the criterion measure.

METHODS

Participants were a subsample (N = 121, 24 ± 1.7 yrs) from a large longitudinal cohort study. Participants completed a detailed 1-year physical activity recall, wore an accelerometer for 1 week and then completed a brief 1-week physical activity recall when they returned the accelerometer.

RESULTS

Mean values for moderate-to-vigorous physical activity (MVPA) from the 3 instruments were 3.2, 2.2, and 13.7 hours/wk for the accelerometer, 1-week recall, and 1-year recall, respectively (all different from each other, P < .001). Spearman correlations for moderate, vigorous, and MVPA between the accelerometer and the 1-week recall (0.30, 0.50, and 0.40, respectively) and the 1-year recall (0.31, 0.42, and 0.44, respectively) demonstrated adequate validity.

CONCLUSIONS

Both recall instruments may be used for ranking physical activity at the group level. At the individual level, the 1-week recall performed much better in terms of absolute value of physical activity. The 1-year recall overestimated total physical activity but additional research is needed to fully test its validity.

Differences in brain activity during a verbal associative memory encoding task in high- and low-fit adolescents

Aerobic fitness is associated with better memory performance as well as larger volumes in memory-related brain regions in children, adolescents, and elderly. It is unclear if aerobic exercise also influences learning and memory functional neural circuitry. Here, we examine brain activity in 17 high-fit (HF) and 17 low-fit (LF) adolescents during a subsequent memory encoding paradigm using fMRI. Despite similar memory performance, HF and LF youth displayed a number of differences in memory-related and default mode (DMN) brain regions during encoding later remembered versus forgotten word pairs. Specifically, HF youth displayed robust deactivation in DMN areas, including the ventral medial PFC and posterior cingulate cortex, whereas LF youth did not show this pattern. Furthermore, LF youth showed greater bilateral hippocampal and right superior frontal gyrus activation during encoding of later remembered versus forgotten word pairs. Follow-up task-dependent functional correlational analyses showed differences in hippocampus and DMN activity coupling during successful encoding between the groups, suggesting aerobic fitness during adolescents may impact functional connectivity of the hippocampus and DMN during memory encoding. To our knowledge, this study is the first to examine the influence of aerobic fitness on hippocampal function and memory-related neural circuitry using fMRI. Taken together with previous research, these findings suggest aerobic fitness can influence not only memory-related brain structure, but also brain function.

Sugar-Added Beverages and Adolescent Weight Change

OBJECTIVE

The increase in consumption of sugar-added beverages over recent decades may be partly responsible for the obesity epidemic among U.S. adolescents. Our aim was to evaluate the relationship between BMI changes and intakes of sugar-added beverages, milk, fruit juices, and diet soda.

RESEARCH METHODS AND PROCEDURES

Our prospective cohort study included >10,000 boys and girls participating in the U.S. Growing Up Today Study. The participants were 9 to 14 years old in 1996 and completed questionnaires in 1996, 1997, and 1998. We analyzed change in BMI (kilograms per meter squared) over two 1-year periods among children who completed annual food frequency questionnaires assessing typical past year intakes. We studied beverage intakes during the year corresponding to each BMI change, and in separate models, we studied 1-year changes in beverage intakes, adjusting for prior year intakes. Models included all beverages simultaneously; further models adjusted for total energy intake.

RESULTS

Consumption of sugar-added beverages was associated with small BMI gains during the corresponding year (boys: +0.03 kg/m2 per daily serving, p = 0.04; girls: +0.02 kg/m2, p = 0.096). In models not assuming a linear dose-response trend, girls who drank 1 serving/d of sugar-added beverages gained more weight (+0.068, p = 0.02) than girls drinking none, as did girls drinking 2 servings/d (+0.09, p = 0.06) or 3+ servings/d (+0.08, p = 0.06). Analyses of year-to-year change in beverage intakes provided generally similar findings; boys who increased consumption of sugar-added beverages from the prior year experienced weight gain (+0.04 kg/m2 per additional daily serving, p = 0.01). Children who increased intakes by 2 or more servings/d from the prior year gained weight (boys: +0.14, p = 0.01; girls +0.10, p = 0.046). Further adjusting our models for total energy intake substantially reduced the estimated effects, which were no longer significant.

DISCUSSION

Consumption of sugar-added beverages may contribute to weight gain among adolescents, probably due to their contribution to total energy intake, because adjustment for calories greatly attenuated the estimated associations.

Aerobic fitness relates to learning on a virtual Morris Water Task and hippocampal volume in adolescents

In rodents, exercise increases hippocampal neurogenesis and allows for better learning and memory performance on water maze tasks. While exercise has also been shown to be beneficial for the brain and behavior in humans, no study has examined how exercise impacts spatial learning using a directly translational water maze task, or if these relationships exist during adolescence--a developmental period which the animal literature has shown to be especially vulnerable to exercise effects. In this study, we investigated the influence of aerobic fitness on hippocampal size and subsequent learning and memory, including visuospatial memory using a human analogue of the Morris Water Task, in 34 adolescents. Results showed that higher aerobic fitness predicted better learning on the virtual Morris Water Task and larger hippocampal volumes. No relationship between virtual Morris Water Task memory recall and aerobic fitness was detected. Aerobic fitness, however, did not relate to global brain volume or verbal learning, which might suggest some specificity of the influence of aerobic fitness on the adolescent brain. This study provides a direct translational approach to the existing animal literature on exercise, as well as adds to the sparse research that exists on how aerobic exercise impacts the developing human brain and memory.

Yoga and Pilates: associations with body image and disordered-eating behaviors in a population-based sample of young adults

OBJECTIVE

To examine associations between participating in mind-body activities (yoga/Pilates) and body dissatisfaction and disordered eating (unhealthy and extreme weight control practices and binge eating) in a population-based sample of young adults.

METHOD

The sample included 1,030 young men and 1,257 young women (mean age: 25.3 years, SD = 1.7) who participated in Project EAT-III (Eating and Activity in Teens and Young Adults).

RESULTS

Among women, disordered eating was prevalent in yoga/Pilates participants and nonparticipants, with no differences between the groups. Men participating in yoga/Pilates were more likely to use extreme weight control behaviors (18.6% vs. 6.8%, p = .006) and binge eating (11.6% vs. 4.2%, p = .023), and marginally more likely to use unhealthy weight control behaviors (49.1% vs. 34.5%; p = .053), than nonparticipants after adjusting for sociodemographics, weight status, and overall physical activity.

DISCUSSION

Findings suggest the importance of helping yoga/Pilates instructors recognize that their students may be at risk for disordered eating.

Seasonal variation in physical activity among children and adolescents: a review

The purpose of this review was to examine seasonal variation in physical activity among children and adolescents. Searches were conducted of electronic databases for studies on seasonal differences in physical activity levels. A total of 35 studies, including children and adolescents between the ages of 2-19 years, were reviewed. Overall, 83% (29/35) of the studies found seasonal variation in physical activity among children and/or adolescents. The results were consistent regardless of the region, physical activity measure, or the study design but the findings were inconsistent across age categories.

School opportunities and physical activity frequency in nine year old children

OBJECTIVE

To examine the association between physical activity (PA) opportunities at school and participation in PA outside of school physical education (PE) classes among 9 year old children.

METHODS

Data were obtained in a representative sample of 1 267 students nested within 69 schools who completed questionnaires; principals provided data on schools. Students' PA frequency was defined as all reported episodes of past week PA, excluding PE class. Schools were categorized as "high-opportunity" if they provided > or = 4 of the following opportunities: PE class > or = 2 times/week, extracurricular sports animator, gymnasium, swimming pool, schoolyard equipped for games, and > or = 1 outdoor sports playing fields. Multilevel modelling techniques were used to investigate the association between school-level PA opportunity and student-level PA frequency.

RESULTS

No main effect of school-level PA opportunities on PA frequency was observed. However, overweight boys attending high-opportunity schools were significantly more active than those attending low-opportunity schools.

CONCLUSIONS

The association between PA frequency and school-level PA opportunity differs by sex and weight status. Overweight boys in particular may benefit from health promotion strategies providing greater opportunities for school PA.

Risk factors and comorbidities associated with obesity in children and adolescents after the arterial switch operation and Ross procedure

BACKGROUND

Over 25% of patients with congenital heart disease are obese (OB) or overweight (OW). Unique factors such as activity restriction and early feeding practices may play a role. We evaluated a high-risk cohort predisposed to early coronary artery disease due to past surgery involving coronary artery reimplantation.

METHODS

Patients at our institution who underwent the arterial switch or Ross operation were included. Data collection included chart review and activity and diet questionnaires. The proportion of OB/OW (body mass index > or =85%) was compared to national data. Factors associated with OB/OW were evaluated.

RESULTS

A total of 106 patients were enrolled. Median age was 14.2 years (6.0-19.9 years); 69% were male. Similar to national data, 31% were OB/OW (vs 31%, P = nonsignificant [NS]). There was no difference comparing OB/OW to normal-weight patients in activity restriction (cardiologist documented 27% vs 27%; parent reported 38% vs 42%, P = NS), activity level (9.8 hours/week [1.7-41.2] vs 11.5 [0.8-52.3], P = NS), or early feeding practices (formula vs breastfeeding, caloric fortification, tube feeding). OB/OW patients were more likely to have an OB parent (70% vs 37%, P = .01). Left ventricular mass index was higher in OB/OW patients (48.8 g/m(2.7) [24.4-120.6] vs 37.7 g/m(2.7) [16.5-85.1], P = .01).

CONCLUSIONS

Nearly one third of ASO and Ross patients were OB/OW. Obese/overweight was not found to be related to activity restriction or early feeding practices, but was associated with parental obesity. Obese or OW patients had higher left ventricular mass. Obesity and associated comorbidities may pose additional cardiovascular risk in this unique population who underwent coronary artery reimplantation in childhood.

Physical activity inversely associated with the presence of depression among urban adolescents in regional China

BACKGROUND

An inverse relationship between physical activity (PA) and depression among adolescents has been reported in developed communities without consideration of sedentary behaviors (SB, including sitting for course study, viewing TV, and sleeping). We explored the association between recreational PA time (hr/wk) and depression after adjustment with SB and other possible confounders among Chinese adolescents.

METHODS

A population-based cross-sectional study was conducted in Nanjing municipality of China in 2004 using a multi-stage cluster sampling approach. A total of 72 classes were randomly selected from 24 urban junior high schools and all students completed the structured questionnaire. Adolescent depression was examined by the Children's Depression Inventory (CDI) of Chinese version with cutoff point value of 20 or above as the presence of depression. Recreational PA time was measured by a question on weekly hours of PA outside of school. Descriptive statistics, multivariate logistic and linear regression models were used in analysis.

RESULTS

The overall prevalence of depression was 15.7% (95%CI: 14.3%, 17.1%) among 2,444 eligible participants. It was found that physical activity was negatively associated with depression. After adjustment for sedentary behaviors and other potential confounders, participants who spent 1-7 hr/wk, 8-14 hr/wk and 15+ hr/wk for recreational PA, respectively, had odds ratios of 0.70 (95% CI = 0.57, 0.86), 0.68 (95% CI = 0.53, 0.88) and 0.66 (95% CI = 0.50, 0.87) for likelihood of being depressive, compared to their counterparts who spent 0-0.9 hr/wk for PA. This inverse relationship between PA time and depression remained statistically significant by gender and grade.

CONCLUSION

This study, conducted among Chinese adolescents, strengthened the evidence that physical activity was inversely associated with depression. Our study has important implications for health officers and public health professionals to pay much attention to the relationship between physical activity and depression in Mainland China.

Diet and physical activity patterns of school-aged children

Childhood provides an opportunity for establishing healthful lifestyle habits, yet little is known about diet and physical activity patterns of elementary school-aged children. A cohort of 35 boys and girls in grades 3 through 5 (mean age=9.5 years) was studied during the course of the 2004-2005 school year, providing seasonal assessments of diet and physical activity. Objectively measured data included height, weight, and pedometer step counts. Subjective data included seasonal 3-day diet diaries, a food frequency questionnaire, and a physical activity questionnaire. Participants were white, well-nourished, and within the healthy range for body mass index for age. Only three students (9%) were overweight and another three were "at risk" for overweight. Food intake patterns fell far below MyPyramid guidelines for average daily servings of fruits and vegetables. High intakes of saturated fat (average of 12% of calories) and sodium were noted, along with inadequate fiber intakes. Snacks, desserts, and entrees that contributed most to calorie and saturated fat intake were identified. Self-reported physical activity appears in line with recommendations, but step counts fall short, particularly for girls and during winter months. These findings identify targets for behavioral and environmental interventions to reduce childhood obesity risks. Additional research involving more diverse populations is warranted.

Patterns and determinants of physical activity in U.S. adolescents

PURPOSE

The objectives of this study were to describe longitudinal trends in adolescent physical activity in a sample of U.S. adolescents and to assess the effect of multiple individual, parental, and environmental factors on initial level and rates of change in adolescent physical activity.

METHODS

Study subjects were 12,812 boys and girls 10 to 18 years of age who were participating in the Growing Up Today Study and their mothers. We used accelerated longitudinal analysis to describe trajectories of physical activity from 1997-1999, and random effects linear mixed models to determine which factors were independently associated with baseline physical activity and changes in physical activity over time.

RESULTS

Mean hours of physical activity ranged from 7.3-11.6 hours per week in boys and from 8.0-11.2 hours per week in girls. Physical activity was best modeled as a quadratic function of age, increasing until early adolescence and declining after age 13 in boys and girls. Multivariable modeling demonstrated that variables associated with physical activity level at baseline in boys and girls were age, body mass index, psychosocial variables, personal attitudes about body shape, perceived peer attitudes about body shape/fitness, parental attitudes about physical activity, parental physical activity, and environmental barriers to physical activity. Age was the only factor that predicted change in physical activity over time.

CONCLUSIONS

Interventions to increase physical activity in adolescents should begin before adolescence. Interventions may be more effective if they are multimodal and focus on modifiable individual, parental, and environmental factors.

Modifiable lifestyle factors affecting bone health using calcaneus quantitative ultrasound in adolescent girls

One hundred and fourteen girls were measured for calcaneus QUS (stiffness index score), calcium intake, weight, and total hours spent in physical activity (moderate to high-impact activities and low to no-impact activities). Multiple regression analysis indicated that hours spent in moderate to high-impact activities, current calcium intake, and weight significantly predicted SI.

INTRODUCTION

To determine the influence of modifiable lifestyle factors on adolescent girls' bone health measured by calcaneus quantitative ultrasound (QUS).

METHODS

One hundred and fourteen girls, ages 14-18 (15.97 +/- .7), enrolled in high school physical education classes, were measured for calcaneus QUS (stiffness index score), height, weight, current calcium intake from 2-3 day food records, and estimated total hours spent in physical activity from kindergarten to present. Cumulative physical activity hours were separated into two classifications (according to their estimated strain from ground reaction force): moderate to high-impact activities and low to no-impact activities.

RESULTS

Pearson correlations between stiffness index (SI) and age, height, weight, current calcium intake, and hours spent in moderate to high-impact versus low to no-impact activities indicated a positive relationships between SI and weight (r = .259, p = .005), current calcium intake (r = .286, p = .002), and hours spent in moderate to high-impact activities (r = .451, p < .001). Multiple regression between SI and the above independent variables indicated that collectively, hours spent in moderate to high-impact activities, current calcium intake, and weight (r (2) = .363, p = <.001) significantly predicted SI.

CONCLUSION

Our data indicate that moderate to high-impact activities, current calcium intake, and weight positively influence bone properties of the calcaneus in adolescent girls.

Preventing risk for obesity by promoting self-regulation and decision-making skills: pilot results from the PATHWAYS to health program (PATHWAYS)

The overall aim of the two school-based pilot studies was to evaluate whether an approach to prevention that focused on changing child impulse control, decision making, and social competence can be effective in changing attitudes toward food intake and physical activity as risk factors for obesity. The strategy used was to translate specific components of one evidence-based program for violence prevention (Promoting Alternative Thinking Strategies: PATHS) into an elementary school curriculum program for obesity prevention. Both studies demonstrated significant changes in positive attitudes toward self-regulation of appetitive behavior. In addition, Study 2 demonstrated positive changes in actual food choices and television viewing patterns. Implications are that comprehensive efforts to prevent youth risk for obesity should include as one component school-based curricula that target self-regulation and decision-making skills.

Adolescent physical activity and perceived competence: does change in activity level impact self-perception?

PURPOSE

To determine whether change in physical activity level impacts adolescents' self-perceptions.

METHODS

Using questionnaire responses from the Growing Up Today Study (GUTS) in 1997 and 1999, we evaluated data from 5260 girls and 3410 boys. Physical activity changes were compared to changes in perceived competence in three domains (social, athletic, and scholastic) as well as in global self-worth. Analyses controlled for sibling clustering as well as for potential confounders, including body mass index, cigarette smoking, baseline activity levels, and baseline self-perception scores.

RESULTS

For girls and boys, increase in physical activity was positively associated with change in social and athletic (p < .0001), but not scholastic or global, self-perception. Compared to those with little or no change in activity, those who increased physical activity were more likely to have increased self-perception measures. Girls who increased physical activity by 5 or more hours/week were at least 33% more likely to have increased social self-perception, and at least 44% more likely to have increased athletic self-perception. In boys, those who increased activity by 10 or more hours/week were 45% more likely to have increased social self-perception. The reverse was also true; for both girls and boys, those with decreased physical activity were more likely to have decreased self-perception scores.

CONCLUSIONS

This research indicates that increased physical activity has a positive impact on athletic and social self-perception in girls and boys.

Longitudinal relationship between television viewing and leisure-time physical activity during adolescence

OBJECTIVE

The goal was to examine the longitudinal associations of changes in television viewing and other sources of sedentary behavior with changes in leisure-time moderate/vigorous physical activity in adolescence.

METHODS

We studied a cohort of 6369 girls and 4487 boys who were 10 to 15 years of age in 1997. During each of 4 years of follow-up assessments, participants self-reported their weekly hours of television viewing. By using a seasonal questionnaire, we also obtained detailed information on physical activities over the previous year, from which we calculated total leisure-time moderate/vigorous physical activity. We performed linear regression analyses to assess the longitudinal associations between 1-year changes in television viewing and 1-year changes in leisure-time moderate/vigorous physical activity during the same year, using data from 1997 through 2001.

RESULTS

One-year changes (mean +/- SD) were -0.13 +/- 7.2 hours/week for leisure-time moderate/vigorous physical activity, -0.55 +/- 7.0 hours/week for television viewing, and -1.02 +/- 11.0 hours/week for total sedentary behaviors. In longitudinal models adjusted for age, age2, gender, race/ethnicity, Tanner stage, menarche (in girls), baseline physical activity, and baseline television viewing, we found no substantive relationship between year-to-year changes in television viewing and changes in leisure-time moderate/vigorous physical activity (0.03 hours/week, for each 1-hour/week change in television viewing). There were no material associations in age or gender subgroups.

CONCLUSIONS

In this longitudinal study, changes in television viewing were not associated with changes in leisure-time moderate/vigorous physical activity. Our findings suggest that television viewing and leisure-time physical activity are separate constructs, not functional opposites.

Breast-feeding and overweight in adolescence: within-family analysis [corrected]

BACKGROUND

Previous reports have found associations between having been breast-fed and a reduced risk of being overweight. These associations may be confounded by sociocultural determinants of both breast-feeding and obesity. We addressed this possibility by assessing the association of breast-feeding duration with adolescent obesity within sibling sets.

METHODS

We surveyed 5,614 siblings age 9 to 14 years and their mothers. These children were a subset of participants in the Growing Up Today Study, in which we had previously reported an inverse association of breast-feeding duration with overweight. We compared the prevalence of overweight (body mass index exceeding the age-sex-specific 85th percentile) in siblings who were breast-fed longer than the mean duration of their sibship with those who were breast-fed for a shorter period. Then we compared odds ratios from this within-family analysis with odds ratios from an overall (ie, not within-family) analysis.

RESULTS

Mean +/- standard deviation breast-feeding duration was 6.4 +/- 4.0 months, and crude prevalence of overweight was 19%. On average, siblings who were breast-fed longer than their family mean had breast-feeding duration 3.7 months longer than their shorter-duration siblings. The adjusted odds ratio (OR) for overweight among siblings with longer breast-feeding duration, compared with shorter duration, was 0.92 (95% confidence interval = 0.76-1.11). In overall analyses, the adjusted OR was 0.94 (0.88-1.00) for each 3.7-month increment in breast-feeding duration.

CONCLUSION

The estimated OR for the within-family analysis was close to the overall estimate, suggesting that the apparent protective effect of breast-feeding on later obesity was not highly confounded by unmeasured sociocultural factors. A larger study of siblings, however, would be needed to confirm this conclusion.

Association of consumption of fried food away from home with body mass index and diet quality in older children and adolescents

OBJECTIVES

Rates of overweight have increased dramatically among children in the United States. Although an increase in consumption of food prepared away from home has paralleled overweight trends, few data exist relating food prepared away from home to change in BMI in children. The goals of this study were to (1) examine the cross-sectional and longitudinal associations between consumption of fried foods away from home (FFA) and BMI and (2) examine the cross-sectional associations between intake of FFA and several measures of diet quality.

METHODS

We studied a cohort of 7745 girls and 6610 boys, aged 9 to 14 years, at baseline in 1996. We obtained BMI from self-reported height and weight, measures of diet quality from a food frequency questionnaire, and weekly servings of FFA during the previous year. We performed linear regression analyses to assess the longitudinal associations between change in consumption of FFA on change in BMI, using data from three 1-year periods from 1996 through 1999. We also related consumption of FFA with intake of selected foods and nutrients at baseline.

RESULTS

In cross-sectional analyses, adjusting for potential confounders, mean (SE) BMI was 19.1 (0.13) among children who ate FFA "never or <1/week," 19.2 (0.13) among those who responded "1 to 3 times/week," and 19.3 (0.18) among those who responded "4 to 7 times/week." In longitudinal multivariate models, increasing (over 1 year) consumption of FFA "never or <1/week" to "4 to 7/week" was associated with increasing BMI (beta = 0.21 kg/m2; 95% confidence interval: 0.03-0.39) compared with those with low consumption of FFA at baseline and 1 year later. At baseline, frequency of eating FFA was associated with greater intakes of total energy, sugar-sweetened beverages, and trans fat, as well as lower consumption of low-fat dairy foods and fruits and vegetables.

CONCLUSIONS

These data suggest that older children who consume greater quantities of FFA are heavier, have greater total energy intakes, and have poorer diet quality. Furthermore, increasing consumption of FFA over time may lead to excess weight gain.

Family dinner and adolescent overweight

OBJECTIVE

The purpose of this study was to examine both cross-sectional and longitudinal associations between frequency of family dinner and overweight status in a large sample of 9- to 14-year-old children.

RESEARCH METHODS AND PROCEDURES

We studied a cohort of 7784 girls and 6647 boys, 9 to 14 years of age at baseline in 1996, participating in the Growing Up Today Study. From annual mailed surveys, we calculated BMI from self-reported height and weight and assessed frequency of family dinner over the previous year. We defined "overweight" as age- and sex-specific BMI >85th percentile. We performed multiple logistic regression analyses; the longitudinal analyses assessed the association of previous year family dinner consumption with 1-year incidence of becoming overweight, using prospective data from 1996 through 1999.

RESULTS

At baseline in 1996, 16% of participants had family dinner "never or some days," 40% on "most days," and 44% "every day." Across these categories, overweight prevalence for girls was 19.4%, 16.6%, and 16.7% and for boys was 24.6%, 23.3%, and 22.7%, respectively. In cross-sectional analyses, adjusting for potential confounders, the odds of being overweight was 0.85 [95% confidence interval (CI): 0.76, 0.96] among children who ate family dinner on "most days" or "every day" compared with those who ate family dinner "never or some days." In longitudinal multivariate models, the odds ratios between previous year frequency of eating family dinner and 1-year incidence of becoming overweight were 0.95 (95% CI: 0.78, 1.16) and 1.04 (95% CI: 0.85, 1.27) for children who ate family dinner on "most days" and "every day," respectively, compared with those who ate family dinner "never or some days."

DISCUSSION

The frequency of eating family dinner was inversely associated with overweight prevalence at baseline but not with likelihood of becoming overweight in longitudinal analyses.

The STRENGTH Ezine: an application of e-mail for health promotion in adolescent girls

PURPOSE

Few studies have investigated the efficacy of e-mail for promoting behavior change. This study evaluates the participation in and outcomes associated with an e-mail-based health promotion program.

METHODS

Adolescent girls aged 15 to 17 years were recruited at a shopping mall. Participants with an e-mail address were assigned to the interactive e-mail magazine (Ezine) group (n = 37), whereas those not reporting an e-mail address were assigned to the non-Ezine group (n = 33). Participants in the Ezine group received the health Ezine, which included a quiz and an advice column, on a weekly basis.

RESULTS

Results indicate that among the Ezine group, there was a high recall of the Ezine (81.1%), and more than one third of the participants replied to Ezine volumes with quiz answers or an advice question (36.6%). Differences in health behavior change between the Ezine and non-Ezine groups were not significant.

CONCLUSIONS

E-mails on health-related matters can generate moderate levels of involvement in adolescent girls. Given the widespread use of e-mail, more studies are needed on the effective application of e-mail for health behavior change.

Assessment of factors affecting the validity of self-reported health-risk behavior among adolescents: evidence from the scientific literature

We reviewed the existing empirical literature to assess cognitive and situational factors that may affect the validity of adolescents' self-reports of alcohol and other drug use, tobacco use, behaviors related to unintentional injuries and violence, dietary behaviors, physical activity, and sexual behavior. Specifically, we searched for peer-reviewed journal articles published in 1980 or later that examined the factors affecting self-report of the six categories of behavior listed above. We also searched for studies describing objective measures for each behavior. Self-reports of each of six types of health-risk behaviors are affected by both cognitive and situational factors. These factors, however, do not threaten the validity of self-reports of each type of behavior equally. The importance of assessing health-risk behaviors as part of research activities involving adolescents necessitates the use of self-report measures. Researchers should familiarize themselves with the threats to validity inherent in this type of assessment and design research that minimizes these threats as much as possible.

Longitudinal study of skipping breakfast and weight change in adolescents

BACKGROUND

Several cross-sectional studies reported that heavier children eat breakfast less often. However, no longitudinal studies have addressed whether skipping breakfast leads to excessive weight gain.

OBJECTIVE

To investigate whether skipping breakfast was prospectively associated with changes in body fatness.

METHODS

A cohort of >14000 boys and girls from all over the US, 9- to 14-y-old in 1996, returned annual mailed questionnaires (1996-1999) for the Growing Up Today Study. We analyzed change in body mass index (BMI; kg/m(2)) over three 1-y periods among children who reported breakfast frequency.

RESULTS

Children who reported that they never eat breakfast had lower energy intakes than those who eat breakfast nearly every day. Children who were more physically active reported higher energy intakes, as did those who reported more time watching television/videos and playing videogames. Like previous studies, skipping breakfast was associated with overweight, cross-sectionally. However, overweight children who never ate breakfast lost BMI over the following year compared to overweight children who ate breakfast nearly every day (boys: -0.66 kg/m(2) (s.e.=0.22); girls: -0.50 kg/m(2) (s.e.=0.14)). But normal weight children who never ate breakfast gained weight relative to peers who ate breakfast nearly every day (boys: +0.21 kg/m(2) (s.e.=0.13); girls: +0.08 kg/m(2) (s.e.=0.05)). Breakfast frequency was positively correlated with self-reported quality of schoolwork.

CONCLUSIONS

Overweight children who never eat breakfast may lose body fat, but normal weight children do not. Since numerous studies link skipping breakfast to poorer academics, children should be encouraged to eat breakfast.

One-year changes in activity and in inactivity among 10- to 15-year-old boys and girls: relationship to change in body mass index

OBJECTIVE

Cross-sectional studies have suggested that children who were less physically active and children who watched more television (TV) had more excess body weight, but no large nationwide longitudinal studies have addressed whether children who change their personal levels of activity or inactivity, from one year to the next, experience changes in adiposity. Our objective is to study the association between change in body mass index (BMI) over 1 year and same year change in recreational physical activity and change in recreational inactivity (TV/videos/video games).

DESIGN

Cohort study using data from 2 mailed questionnaires, 1 year apart.

PARTICIPANTS

A total of 11 887 boys and girls, aged 10 to 15, who returned questionnaires in both 1997 and 1998 as part of the Growing Up Today Study. Outcome Measure. Change in BMI from 1997-1998, accounting for increases in BMI associated with growth and development.

RESULTS

An increase in physical activity from 1997-1998 was associated with decreasing relative BMI in girls (-0.06 kg/m2 per hour increase in daily activity; 95% confidence interval [CI]: -0.11, -0.01) and in overweight boys (-0.22 kg/m2; CI: -0.33, -0.10). An increase in inactivity was associated with increasing BMI in girls (+0.05 kg/m2 per hour increase in daily TV/videos/video games; CI: +0.02, +0.08). Effects were generally stronger among overweight children. Increasing time doing aerobics/dancing and walking were associated with BMI declines for some groups of children.

CONCLUSIONS

Many children may benefit by increasing their physical activity and by reducing time watching TV or videos and playing video games. In particular, 2 activities accessible to most children, aerobics/dancing and walking, also appeared beneficial.

Maternal gestational diabetes, birth weight, and adolescent obesity

OBJECTIVE

Obesity increases risk of many adverse outcomes, but its early origins are obscure. Gestational diabetes mellitus (GDM) reflects a metabolically altered fetal environment associated with high birth weight, itself associated with later obesity. Previous studies of GDM and offspring obesity, however, have been few and conflicting. The objectives of this study were to examine associations of birth weight and GDM with adolescent body mass index (BMI) and to determine the extent to which the effect of GDM is explained by its influence on birth weight or by maternal adiposity.

METHODS

We conducted a survey of 7981 girls and 6900 boys, 9 to 14 years of age, who are participants in the Growing Up Today Study, a US nationwide study of diet, activity, and growth. In 1996, participants reported height, weight, diet, activity, and other variables by self-administered mailed questionnaire. We linked these data with information reported by their mothers, participants in the Nurses' Health Study II, including GDM, height, current weight, and child's birth weight. We excluded births <34 weeks' gestation and mothers who had preexisting diabetes. We defined overweight as BMI (kg/m(2)) >95th percentile, and at risk for overweight as 85th to 95th percentile, for age and gender from US national data.

RESULTS

Mean birth weight was 3.4 kg for girls and 3.6 kg for boys. Among the 465 subjects whose mothers had GDM, 17.1% were at risk for overweight and 9.7% were overweight in early adolescence. In the group without maternal diabetes, these estimates were 14.2% and 6.6%, respectively. In multiple logistic regression analysis, controlling for age, gender, and Tanner stage, the odds ratio for adolescent overweight for each 1-kg increment in birth weight was 1.4 (95% confidence interval: 1.2-1.6). Adjustment for physical activity, television watching, energy intake, breastfeeding duration, mother's BMI, and other maternal and family variables reduced the estimate to 1.3 (1.1-1.5). For offspring of mothers with GDM versus no diabetes, the odds ratio for adolescent overweight was 1.4 (1.1-2.0), which was unchanged after controlling for energy balance and socioeconomic factors. Adjustment for birth weight slightly attenuated the estimate (1.3; 0.9-1.9); adjustment for maternal BMI reduced the odds ratio to 1.2 (0.8-1.7).

CONCLUSIONS

Higher birth weight predicted increased risk of overweight in adolescence. Having been born to a mother with GDM was also associated with increased adolescent overweight. However, the effect of GDM on offspring obesity seemed only partially explained by its influence on birth weight, and adjustment for mother's own BMI attenuated the GDM associations. Our results only modestly support a causal role of altered maternal-fetal glucose metabolism in the genesis of obesity in the offspring. Alternatively, GDM may program risk for a postnatal insult leading to obesity, or it may merely be a risk marker, not in the causal pathway.