Individual characteristics and public or private schools predict the body mass index of Brazilian children: a multilevel analysis

Trends in the prevalence of obesity, overweight, and thinness among schoolchildren aged 7-14 years from southern Brazil (2002-2019)

OBJECTIVE

To analyze the obesity, overweight, and thinness trends among Brazilian schoolchildren by sex, age group, and type of school according to World Health Organization (WHO) and International Obesity Task Force (IOTF) criteria.

METHODS

We conducted four surveys between 2002 and 2018/19 involving schoolchildren aged 7-14 years from a state capital in southern Brazil. Weight status was classified using both WHO and IOTF criteria.

RESULTS

In the total sample, obesity prevalence based on the IOTF and the WHO criteria were 72% and 44% higher in 2018/19 compared with 2002, respectively. Over the whole period, the obesity prevalence increased among children (WHO: 10.1% vs. 14.1%; IOTF: 5.0% vs. 8.3%), and those from public schools (WHO: 10.5% vs. 16.4%; IOTF: 5.6% vs. 10.1%). There was no significant reduction in thinness prevalence over the analyzed period.

CONCLUSION

Obesity prevalence remains on an upward trend in a state capital in southern Brazil, especially among children from public schools. A higher prevalence of overweight and obesity was observed using the WHO criteria compared with IOTF criteria.

Methodological aspects and characteristics of participants in the study on the prevalence of obesity in children and adolescents in Florianópolis, Southern Brazil, 2018-2019: EPOCA study

PURPOSE

To describe the methodological aspects and characteristics of the participants of the EPOCA survey.

METHODS

The study was conducted with schoolchildren aged between seven to 14 years old from 30 schools in Florianópolis, Southern Brazil. Body mass, height, girths, and skinfold thicknesses were measured. Food consumption and physical activity from the previous day were self-reported using the validated Web-CAAFE questionnaire. Adolescents completed a specific questionnaire about physical activity, meal consumption, and weight control behaviors. Parents/guardians responded to a sociodemographic and habits questionnaire.

RESULTS

A total of 1671 schoolchildren participated in the study (response rate: 27.2%). About 63% of schoolchildren were enrolled in public schools. Most studied in the morning shift (54.2%), were female (53.1%) and aged between seven and 10 years (58.1%). The prevalence of overweight was 33.7% and obesity was 11.3%.

CONCLUSIONS

The data obtained will allow us to assess the trend in the prevalence of overweight and obesity and associated factors when compared to other surveys performed. Descriptions of the logistics and protocols can help in the development and improvement of similar studies. It is hoped that the results of EPOCA 2018/2019 may help in the design of obesity prevention policies and programs for this population.

Assessment of the median ages at sexual maturation stages of Brazilian schoolchildren according to overweight status and type of school over a 5-year period: 2007-2012/2013

OBJECTIVES

A secular trend of earlier puberty has been observed in girls, and, although more uncertain in boys, is associated with an increasing trend in the prevalence of overweight and obesity. We aimed to compare the median ages of sexual maturation stages in schoolchildren from a city in southern Brazil over a 5-year period, according to weight status and type of school.

METHODS

Two cross-sectional studies were performed in 2007 and 2012/2013, including 2215 and 1614 schoolchildren, respectively. Body mass index z-scores were calculated and categorized as either nonoverweight or overweight (including obesity). The type of school was categorized as either public or private. Sexual maturation was self-assessed according to the Tanner stages. Mann-Whitney and Kruskal-Wallis tests were performed to compare the median ages of sexual maturation stages.

RESULTS

The median age decreased for almost all stages over the 5-year period in both sexes. In boys, the decrease ranged from 0.3 to 1.0 years (stages 2, 3, 4, and 5 for genitalia, and stages 2 and 4 for pubic hair), and from 0.3 to 0.7 years (stages 2, 3, and 4 for breast, and stages 3, 4, and 5 for pubic hair). In 2012, overweight students had lower median ages for most stages compared to those in 2007, especially in girls. Differences by type of school were balanced across years.

CONCLUSIONS

The median age of Tanner's stages after 5 years was reduced in both sexes. In overweight girls, the reduction was more pronounced. The results by type of school were inconsistent.

ASSOCIATION BETWEEN BREASTFEEDING AND OVERWEIGHT/OBESITY IN SCHOOLCHILDREN AGED 7-14 YEARS

Objective:

To evaluate the prevalence of breastfeeding (BF) and the association between occurrence/duration of BF and overweight/obesity in schoolchildren aged 7-14 years.

Methods:

This is a cross-sectional study, conducted in 2012-2013, on schoolchildren aged 7-14 years from Florianópolis, Santa Catarina, Southern Brazil. Weight and height were measured according to procedures of the World Health Organization. Breastfeeding and sociodemographic data were obtained from a questionnaire responded by parents/guardians. BF was categorized as a dichotomous variable (yes/no) and according to duration (months). Nutritional status was evaluated according to the Z score of the body mass index per age for sex and it was categorized into two groups: normal weight (<Z score+1) and overweight/obesity (≥Z score+1). The adjusted analysis was performed by logistic regression in two age strata (age groups of 7-10 and 11-14 years).

Results:

6.6% of schoolchildren had never breastfed; 16.8% had been breastfed for ≤3 months; 16.7%, for 4-6 months; and 59.9%, for ≥7 months. No statistically significant differences were found in the occurrence and duration of BF between the age groups. The prevalence of overweight/obesity was 34.2%. For age groups (7-10 and 11-14 years), the prevalence of overweight/obesity was 36.7% and 29.8%, respectively. Chance of overweight/obesity for the age group of 7-10 years was lower among schoolchildren who were breastfed (OR=0.54; 95%CI 0.33-0.88), when compared with those who never breastfed. When categorized, the chance of overweight/obesity in the age group of 7-10 years was lower for duration of BF ≤3 months (OR=0.41; 95%CI 0.20-0.83), and 4-6 months (OR=0.48; 95%CI 0.28-0.82) when compared with children who never breastfed.

Conclusions:

BF for at least six months was associated with a lower chance of overweight/obesity for schoolchildren aged 7-10 years. No association was found for schoolchildren aged 11-14 years.

Time trends in the prevalence of breastfeeding among schoolchildren from public and private schools in Florianópolis, Southern Brazil: From 2002 to 2013

OBJECTIVE

To describe breastfeeding trends from 2002 to 2012/2013, and to investigate whether breastfeeding practices differ between mothers of children in public and private schools.

METHODS

Data were obtained from three school-based cross-sectional studies conducted with 7 to 10 years old children. The total sample was 7264 individuals. Data related to breastfeeding were analyzed descriptively and compared using the chi-square test for heterogeneity or trend.

RESULTS

In the 10-year period was observed a decrease in the total percentage of schoolchildren who were not breastfed (12.9%-10.5%) and an increase in the percentage of schoolchildren breastfed for >12 months (23.9%-36.7%). In public schools, the increase of breastfeeding for >12 months was independent of maternal age and years of schooling. In private schools, the increase was observed for schoolchildren born to older mothers and to more educated mothers, although the highest percentage was observed for schoolchildren born to less educated mothers.

CONCLUSIONS

The results confirm the complexity of determining breastfeeding behaviors, and understanding these dynamics is fundamental to develop and improve programs and actions aimed at encouraging, supporting, and protecting breastfeeding. However, strategies developed in Brazil during the first decade of the 21st century should explain the increase of proportion of breastfed children for more than 12 months, and the concomitant decrease of never breastfeed children in the city of Florianopolis (Southern Brazil).