Inequalities in body mass index, diet and physical activity in the UK: Longitudinal evidence across childhood and adolescence

The association between caesarean section delivery and obesity at age 17 years. Evidence from a longitudinal cohort study in the United Kingdom

BACKGROUND

Childhood and adolescent obesity are major, preventable public health concerns. Studies to date are inconclusive regarding an association between caesarean section (CS) delivery and offspring obesity, with fewer studies conducted in late adolescence. This study examined the association between CS delivery, with a specific focus on planned CS, and induction of labour and adolescent body mass index (BMI) and body fat percentage (BF%) at age 17 years.

METHODS

Data on 8,880 mother-child pairs from the United Kingdom Millennium Cohort Study were analysed. The exposures were mode of delivery (normal vaginal delivery (VD) (reference), assisted VD, planned CS and emergency CS) and mode of delivery by induction of labour status. Crude and adjusted binary logistic regression and linear regression models were fitted examining BMI and BF% at age 17 years respectively, adjusting for several potential confounders.

RESULTS

Adolescents born by CS did not have an elevated BMI or BF% compared to those born by normal VD. The fully adjusted results for overweight and obesity in children born by planned CS, compared to VD, were 1.05 (95% CI: 0.86-1.28) and 0.94 (95% CI: 0.72-1.23), respectively. The results were similar for the associations between CS and BF%, and between induction of labour and BMI.

CONCLUSION

Overall, this large longitudinal study did not support an association between CS or induction of labour and overweight, obesity or BF%. It is possible that previously reported associations are due to residual or unmeasured confounding and/or underlying indications for CS delivery.

Beyond correlates: the social gradient in childhood overweight

BACKGROUND

Health (in)equity has a high priority on research and policy agendas. Even though it is known that inequalities in overweight prevalence accumulate with age and are already existent among children below the age of six, research on this topic is scarce. In this young age group, parents play an important role in preventing overweight and associated adverse consequences. This study examines the magnitude of parental misclassification of child weight status and its correlates, focussing on the factors that determine social status and equity.

METHODS

Preschool children's weight and height was measured objectively. Parents gave information on their socioeconomic background. Family education was dichotomised into tertiary and non-tertiary educational level, according to CASMIN. Binary logistic regression, adjusted for parental BMI, was applied to detect odds of childhood overweight.

RESULTS

Data on family educational level and anthropometrics were available from 643 children (4.5 ± 0.82 years, 52.7% male) and their parents of which 46.5% (n = 299) had a tertiary educational background. The groups (tertiary vs. non-tertiary educational level) differ significantly in overweight prevalence (3.7% vs. 11.9%, p ≤ 0.001). Odds of overweight were two times higher in children with non-tertiary educational background (OR: 2.123, CI: 1.010-4.461, p < 0.05), adjusted for parental BMI.

CONCLUSION

Children from families with low educational background have an elevated risk of overweight, already at a very young age. Education in general (not explicitly health education) seems to play a tremendous role in the prevention of overweight and obesity and should therefore be implied in policies enhancing health equity.

TRIAL REGISTRATION

DRKS-ID: DRKS00010089.

Trends in the effects of socioeconomic position on physical activity levels and sedentary behavior among Korean adolescents

OBJECTIVES

We examined trends in physical activity and sedentary behavior in Korean adolescents, and their association with socioeconomic position (SEP).

METHODS

We used data from the Korea Youth Risk Behavior Survey, a nationwide study involving students aged 12-19 conducted between 2009 and 2021. SEP was assessed based on economic status, parental education attainment, and urbanization. Physical activity was categorized into vigorous physical activity, moderate physical activity, and muscle training, and sedentary time was also measured. We conducted the log-binomial regression to calculate prevalence ratios (PRs) and prevalence differences.

RESULTS

Our analysis included a total of 593,896 students. We observed an increasing trend in physical activity, but a worsening trend in sedentary behavior. A positive association was found between an adolescent's physical activity and SEP indicators, except for urbanization. Adolescents with higher economic status engaged in more vigorous physical activity (high: PR, 1.26; 95% confidence interval [CI], 1.25 to 1.28; middle: PR, 1.03; 95% CI, 1.02 to 1.04). Similar associations were observed for father's education (tertiary or above: PR, 1.11; 95% CI, 1.09 to 1.13; upper secondary: PR, 1.05; 95% CI, 1.03 to 1.07) and mother's education (tertiary or above: PR, 1.17; 95% CI, 1.15 to 1.20; upper secondary: PR, 1.06; 95% CI, 1.04 to 1.08). Adolescents with higher economic status also showed a higher compliance rate with the guideline restricting sedentary time to 2 hours per day (high: PR, 1.28; 95% CI, 1.25 to 1.30; middle: PR, 1.03; 95% CI, 1.01 to 1.05).

CONCLUSIONS

Adolescents with higher SEP exhibited more physical activity and less sedentary time than those with lower SEP.

Adolescents' experiences of a school-based health promotion intervention in socioeconomically advantaged and disadvantaged areas in Sweden: a qualitative process evaluation study

BACKGROUND

Adolescence is a transition period in which positive experiences of physical activity have the potential to last into later adulthood. These experiences are influenced by socioeconomic determinants, leading to health inequalities. This study aims to explore adolescents' experiences and participation in a multi-component school-based intervention in schools located in socioeconomically advantaged and disadvantaged areas in Sweden.

METHODS

A qualitative design was used to evaluate how participants experienced the intervention. The intervention was a multi-component school-based intervention. It was conducted in six schools (four control and two intervention schools) with a total of 193 students and lasted one school year. It was teacher-led and consisted of three 60-minute group sessions per week: varied physical activities, homework support with activity breaks, and walks while listening to audiobooks. In total, 23 participant observations were conducted over eight months and 27 students participated in focus groups. A content analysis was conducted.

RESULTS

The results describe a main category 'Engaging in activities depending on socioeconomic status' and three generic categories: 1. Variations in participation in PA together with classmates and teachers; 2. Variations in engagement in PA after school; and 3. Differences in time and place allocated to do homework and listen to audiobooks. These categories illustrate how participants looked forward to the physical activities but used the time spent during the walks and homework support differently depending on how busy they were after school. Frequently, those who were busiest after school were also those from the advantaged area, and those who had little to do after school were from the disadvantaged area.

CONCLUSION

Socioeconomic factors influence participants' possibilities to engage in the intervention activities as well as how they use their time in the activities. This study showed that it is crucial to support adolescents' participation in physical activities by providing structure and engaging well-known teachers in the activities, especially in schools located in disadvantaged areas.

Polygenic and socioeconomic risk for high body mass index: 69 years of follow-up across life

Genetic influences on body mass index (BMI) appear to markedly differ across life, yet existing research is equivocal and limited by a paucity of life course data. We thus used a birth cohort study to investigate differences in association and explained variance in polygenic risk for high BMI across infancy to old age (2-69 years). A secondary aim was to investigate how the association between BMI and a key purported environmental determinant (childhood socioeconomic position) differed across life, and whether this operated independently and/or multiplicatively of genetic influences. Data were from up to 2677 participants in the MRC National Survey of Health and Development, with measured BMI at 12 timepoints from 2-69 years. We used multiple polygenic indices from GWAS of adult and childhood BMI, and investigated their associations with BMI at each age. For polygenic liability to higher adult BMI, the trajectories of effect size (β) and explained variance (R2) diverged: explained variance peaked in early adulthood and plateaued thereafter, while absolute effect sizes increased throughout adulthood. For polygenic liability to higher childhood BMI, explained variance was largest in adolescence and early adulthood; effect sizes were marginally smaller in absolute terms from adolescence to adulthood. All polygenic indices were related to higher variation in BMI; quantile regression analyses showed that effect sizes were sizably larger at the upper end of the BMI distribution. Socioeconomic and polygenic risk for higher BMI across life appear to operate additively; we found little evidence of interaction. Our findings highlight the likely independent influences of polygenic and socioeconomic factors on BMI across life. Despite sizable associations, the BMI variance explained by each plateaued or declined across adulthood while BMI variance itself increased. This is suggestive of the increasing importance of chance ('non-shared') environmental influences on BMI across life.