Tracking of overweight and obesity from early childhood to adolescence in a population-based cohort - the Tromsø Study, Fit Futures

Background

Obesity is a serious childhood health problem today. Studies have shown that overweight and obesity tend to be stable (track) from birth, through childhood and adolescence, to adulthood. However, existing studies are heterogeneous; there is still no consensus on the strength of the association between high birth weight or high body mass index (BMI) early in life and overweight and obesity later in life, nor on the appropriate age or target group for intervention and prevention efforts. This study aimed to determine the presence and degree of tracking of overweight and obesity and development in BMI and BMI standard deviation scores (SDS) from childhood to adolescence in the Fit Futures cohort from North Norway.

Methods

Using a retrospective cohort design, data on 532 adolescents from the Fit Futures cohort were supplemented with height and weight data from childhood health records, and BMI was calculated at 2–4, 5–7, and 15–17 years of age. Participants were categorized into weight classes by BMI according to the International Obesity Taskforce’s age- and sex-specific cut-off values for children 2–18 years of age (thinness: adult BMI <18.5 kg/m², normal weight: adult BMI ≥18.5- < 25 kg/m², overweight: adult BMI ≥25- < 30 kg/m², obesity: adult BMI ≥30 kg/m²). Non-parametric tests, Cohen’s weighted Kappa statistic and logistic regression were used in the analyses.

Results

The prevalence of overweight and obesity combined, increased from 11.5 % at 2–4 years of age and 13.7 % at 5–7 years of age, to 20.1 % at 15–17 years of age. Children who were overweight/obese at 5–7 years of age had increased odds of being overweight/obese at 15–17 years of age, compared to thin/normal weight children (crude odds ratio: 11.1, 95 % confidence interval: 6.4–19.2). Six out of 10 children who were overweight/obese at 5–7 years of age were overweight/obese at 15–17 years of age.

Conclusions

The prevalence of overweight and obesity increased with age. We found a moderate indication of tracking of overweight/obesity from childhood to adolescence. Preventive and treatment initiatives among children at high risk of overweight and obesity should start before 5–7 years of age, but general preventive efforts targeting all children are most important.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0599-5) contains supplementary material, which is available to authorized users.

Social Inequalities in Obesity Persist in the Nordic Region Despite Its Relative Affluence and Equity

Social inequalities in overweight and obesity (OWOB) have persisted in the affluent and reputedly egalitarian Nordic countries. In this review we examine associations between socioeconomic position (SEP) and OWOB, and secular trends in such associations. Determinants and possible causes of the relations are discussed together with opportunities to cope with OWOB as a public health problem. The findings show a persisting inverse social gradient. An interaction between SEP and gender is noted for adults in Denmark, Finland and Iceland and for children in Sweden. There are overall tendencies for increased inequality, however no consistent trend for an increased social gradient in OWOB. Reasons that increased inequality does not unequivocally mirror in a steepened social gradient in obesity may include methodological questions as well as societal efforts to counteract obesity. Multi-level efforts are needed to prevent OWOB.

High prevalence of overweight and obesity among 6-year-old children in Finnmark County, North Norway

AIM

The aim was to determine the prevalence of overweight and obesity among 6-year-old children in Finnmark, the northernmost county of Norway.

METHODS

This is a survey of 1774 children born during 1999 and 2000 from 18 of 19 child healthcare centres in Finnmark. Body mass index data extracted retrospectively in 2007 from health records at the age of 6 years were compared with international definitions of over- and underweight. The prevalence figures were further compared with socio-demographic figures on municipality level.

RESULTS

Overall, 19% of the children were classified as overweight or obese; 5% were classified as obese. The prevalence of overweight and obesity was higher among girls (22%) than among boys (16%) (p < 0.01). The prevalence of underweight was 8% among both girls and boys. Despite large variations in the prevalence of overweight and obesity between municipalities (9-35%), no association was found with municipality figures on socio-demographic factors.

CONCLUSION

In the northernmost county Finnmark, the prevalence of overweight including obesity among 6-year-old children was somewhat higher than in previous surveys from Norway, especially among girls.

Overweight and obesity in Norwegian children: prevalence and socio-demographic risk factors

AIM

The aim of this study was to estimate the prevalence of childhood overweight and obesity and to identify socio-demographic risk factors in Norwegian children.

METHODS

The body mass index of 6386 children aged 2-19 years was compared with the International Obesity Task Force (IOTF) cut-off values to estimate the prevalence of overweight including obesity (OWOB) and obesity (OB). The effect of socio-demographic factors on this prevalence was analysed using multiple ordinal logistic regression analysis in a subsample of 3793 children.

RESULTS

The overall prevalence of OWOB was 13.8% (13.2% in boys and 14.5% in girls, p = 0.146), but the prevalence was higher in primary school children aged 6-11 years (17%, p < 0.001). The risk of being OWOB or OB increased in children with fever siblings (p = 0.003) and with lower parental educational level (p = 0.001). There was no association with parental employment status, single-parent families or origin.

CONCLUSION

The prevalence of OWOB and OB in Norwegian primary school children is of concern. Socio-demographic factors have pronounced effects on the current prevalence of overweight and obesity in a cohort of Norwegian children. This knowledge could help to work out strategies to reduce the burden of overweight and obesity in children.