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What is already known about this subject Factors associated with children's body mass index (BMI) include parents' BMIs, birth weight, maternal smoking, sleep duration and television watching., Few studies have attempted to quantify either changes in the association between risk factors and BMI or the contribution of changes in the risk factors to increases in BMI over a generation., What this study adds The magnitude of the association between most risk factors and children's BMIs has not changed over a 29-year period., Increases in the population level of mothers' body mass index (BMI) explains ∼20% of the increase in children's BMI whereas the smaller increase in fathers' BMI contributes only 6%., Maternal smoking, despite the decrease in prevalence, contributes ∼17%., Objective Using two cohorts born 29 years apart in Dunedin, New Zealand we aim to examine changes in risk factors and their associations with body mass index ( BMI) at ages 3 and 7 years, and estimate their contribution to the secular changes in BMI at age 7 years. Methods Birth weight and anthropometric measures at ages 3, 5 and 7 years were obtained for 974 participants in the Dunedin Multidisciplinary Health and Development Study ( DMHDS), born in 1972-1973, and 241 in the Family Lifestyle, Activity, Movement and Eating Study ( FLAME), born in 2001-2002. Information about maternal age, education and smoking in pregnancy, as well as breastfeeding, children's television time and time in bed, was obtained by questionnaire. Results The increase in BMI over the 29-year period was 0.84 (95% CI 0.61, 1.06) kg m−2 at age 7. A 1-unit difference in the mother's BMI was associated with a 0.06 (0.03, 0.08) kg m−2 difference in offspring in both studies; the 3.4 (2.8, 4.0) kg m−2 increase in the mothers' BMIs accounts for a change of 0.19 kg m−2 in the children's BMI. The much smaller generational increase in fathers' BMI (0.7 kg m−2) correspondingly had a more limited effect on change in child BMI over time (0.06 kg m−2). Although smoking in pregnancy decreased by 15% (8, 21) its association with BMI increased from 0.20 (−0.01, 0.42) in the DMHDS cohort to 1.24 (0.76, 1.71) kg m−2 in the FLAME cohort, contributing 0.18 kg m−2 to the increase in children's BMI. Conclusions Societal factors such as higher maternal BMI and smoking in pregnancy contribute most to the secular increase in BMI, with changes in behavioural factors, including sleep and television viewing, having little effect in this setting. [ABSTRACT FROM AUTHOR]

Background and objectives The ability of bioelectrical impedance ( BIA) to measure change in body composition in children has rarely been examined. Methods Body composition was estimated by BIA (Tanita BC-418) and dual-energy x-ray absorptiometry ( DXA) in 187 children aged 4-8 years at baseline and at 12 months. Change in body composition was compared between the two methods using mixed models. Results Estimates of change in fat mass did not differ between BIA and DXA for overweight girls (mean difference between methods, 95% confidence interval: 0.04 kg, −0.19 to 0.28) or boys (0.07 kg, −0.14 to 0.27). BIA was also able to accurately detect change in fat-free mass, with no significant differences between methods (−0.14 kg, −0.10 to 0.38 in girls and −0.07 kg, −0.35 to −0.20 in boys). Change in percentage fat produced similar estimates in both genders (0.18%, −0.82 to 0.46 in girls and 0.38%, −0.37 to 1.13 in boys). BIA/ DXA comparisons in normal weight children were also not significantly different, with the exception of percentage fat in girls, where BIA slightly underestimated change compared with DXA (0.7%, 0.02-0.37). Conclusion BIA performed well as a measure of change in body composition, providing confidence for its use as an outcome measure in children. [ABSTRACT FROM AUTHOR]

Summary: Background: Prevalence of childhood obesity is high in developed countries, and there is a growing concern regarding increasing socio‐economic disparities. Objectives: To assess trends in the prevalence of overweight, obesity and extreme obesity among New Zealand 4‐year olds, and whether these differ by socio‐economic and ethnic groupings. Methods: A national screening programme, the B4 School Check, collected height and weight data for 75–92% of New Zealand 4‐year‐old children (n = 317 298) between July 2010 and June 2016. Children at, or above, the 85th, 95th and 99.7th percentile for age and sex adjusted body mass index (according to World Health Organization standards) were classified as overweight, obese and extremely obese, respectively. Prevalence rates across 6 years (2010/11 to 2015/16) were examined by sex, across quintiles of socio‐economic deprivation, and by ethnicity. Results: The prevalence of overweight, obesity and extreme obesity decreased by 2.2 [95% CI, 1.8–2.5], 2.0 [1.8–2.2] and 0.6 [0.4–0.6] percentage points, respectively, between 2010/2011 and 2015/2016. The downward trends in overweight, obesity and extreme obesity in the population persisted after adjustment for sex, ethnicity, deprivation and urban/rural residence. Downward trends were also observed across sex, ethnicity and deprivation groups. Conclusions: The prevalence of obesity appears to be declining in 4‐year‐old children in New Zealand across all socio‐economic and ethnic groups. [ABSTRACT FROM AUTHOR]

Summary: Background: Parental inability to recognize child overweight and physician reluctance to instigate discussion prevents behaviour change. Objective: To evaluate parental acceptance of child overweight status following screening. Methods: Interviewers used motivational interviewing or best practice care to discuss overweight status of 271 young children (BMI ≥ 85th) with parents using simple traffic‐light BMI charts. Follow‐up sessions two weeks later (n = 251, 93%) were coded qualitatively to assess parental reactions to the information (overweight diagnosis) and how it was presented (feedback condition). Results: Eight‐two percent of parents rated the charts positively with few (8–10%) feeling judged. Motivational interviewing parents viewed feedback as more empathetic (relative risk, 95% CI: 4.07, 1.64–10.09), but more uncomfortable (12.2, 1.48–100.1) than best practice care parents. Overall, 65.2% of parents accepted their child was overweight, 22.1% were ambivalent and 12.7% rejected the information. Although motivational interviewing parents were less likely to accept it (OR, 95% CI: 0.49, 0.37–0.64) and more likely to be ambivalent (2.01, 1.17–3.47), the most important predictor of acceptance was a positive experience of feedback (P < 0.001). Conclusions: Simple traffic‐light charts facilitate discussion of child overweight status with parents. Style of feedback is less relevant than ensuring a positive experience for parents to increase acceptance of the weight information. [ABSTRACT FROM AUTHOR]