Abstracts

INTRODUCTION

Child obesity has been progressively increasing over the last few decades, being considered a worldwide epidemy by the World Health Organization. It is estimated that 43 million children under 5 years are overweight worldwide, including 35 million in developing countries and 8 million in developed countries¹1 World Health Organization (WHO). Childhood overweight and obesity on the rise. 2010. Disponível em http://www.who.int/dietphysicalactivity/childhood/en/ (Acessado em 18 de setembro de 2010).
Disponível em http:... .

In Europe, one out of five children is overweight and, of those, one-third is obese¹1 World Health Organization (WHO). Childhood overweight and obesity on the rise. 2010. Disponível em http://www.who.int/dietphysicalactivity/childhood/en/ (Acessado em 18 de setembro de 2010).
Disponível em http:... . In the United States, the prevalence of overweight children between 2 to 5 years of age, in the period from 1999 to 2004, increased from 9.5 to 15.1% in male individuals and 11.2 to 12.6% in female ones²2 Ogden CL, Flegal KM, Carroll MD, Johnson CL. Prevalence and trends in overweight among US children and adolescents, 1999-2000. JAMA 2002; 288(14): 1728-32.. In Brazil, studies report that the overweight prevalence in children under 5 years of age range from 2.5%, among lower economic strata, to 16.6% at the highest ones³3 Saldiva SR, Escuder MM, Venancio SI, Benicio MH. Prevalence of obesity in preschool children from five towns in Sao Paulo State, Brazil. Cad Saúde Pública 2004; 20(6): 1627-32.

4 González DA, Nazmi A, Victora CG. Growth from birth to adulthood and abdominal obesity in a Brazilian birth cohort. Int J Obes (Lond) 2010; 34(1): 195-202.

5 Monteiro CA, Conde WL, Konno SC, Lima AL, Silva AC, Benicio MH. Avaliação antropométrica do estado nutricional de mulheres em idade fértil e crianças menores de cinco anos. In: Brasil, Ministério da Saúde. Pesquisa Nacional de Demografia e Saúde da Criança e da Mulher: PNDS 2006: Dimensões do processo reprodutivo e da saúde da criança. Brasília; 2009. p. 213-30. ^{- 6}6 Silva GAP, Balaban G, Motta MEFA. Prevalência de sobrepeso e obesidade em crianças e adolescentes de diferentes condições socioeconômicas. Rev Bras Saúde Mater Infant 2005; 5(1): 53-9.

Several studies have been dedicated into identifying risk factors for excess weight in children, such as birth weight⁴4 González DA, Nazmi A, Victora CG. Growth from birth to adulthood and abdominal obesity in a Brazilian birth cohort. Int J Obes (Lond) 2010; 34(1): 195-202. ^{, 7}7 Martins EB, Carvalho MS. Associação entre peso ao nascer e o excesso de peso na infância: revisão sistemática. Cad Saúde Pública 2006; 22(11): 2281-300. ^{, 8}8 Monteiro PO, Victora CG, Barros FC, Monteiro LM. Birth size, early childhood growth, and adolescent obesity in a Brazilian birth cohort. Int J Obes Relat Metab Disord 2003; 27(10): 1274-82., breastfeeding⁹9 Simon VGN, Souza JMP, Souza SB. Aleitamento materno, alimentação complementar, sobrepeso e obesidade em pré-escolares. Rev Saúde Pública 2009; 43(1): 60-9. ^{, 10}10 Arens S, Von Kries R. Protective effect of breastfeeding against obesity in childhood: can a meta-analysis of published observational studies help to validate the hypothesis? Adv Exp Med Biol 2009; 639: 145-52., family income³3 Saldiva SR, Escuder MM, Venancio SI, Benicio MH. Prevalence of obesity in preschool children from five towns in Sao Paulo State, Brazil. Cad Saúde Pública 2004; 20(6): 1627-32., environmental factors¹¹11 Robinson TN. Reducing children's television viewing to prevent obesity: a randomized controlled trial. JAMA 1999; 282(16): 1561-7. and socioeconomic status¹²12 Spruijt-Metz D. Etiology, treatment and prevention of obesity in childhood and adolescence: a decade in review. J Res Adolesc 2011; 21(1): 129-52..

Victora et al.⁴4 González DA, Nazmi A, Victora CG. Growth from birth to adulthood and abdominal obesity in a Brazilian birth cohort. Int J Obes (Lond) 2010; 34(1): 195-202., when analyzing a cohort of births in 1982, reviewed in 2006, with a sample of 856 individuals and with the objective of evaluating the effects of birth weight and weight gain up to 23 years of age, showed that the gain of weight in the intrauterine phase and in the first 2 years of life are associated to weight increase of abdominal fat in young adults⁴4 González DA, Nazmi A, Victora CG. Growth from birth to adulthood and abdominal obesity in a Brazilian birth cohort. Int J Obes (Lond) 2010; 34(1): 195-202.. Considering the need for health promotion, the early detection of excess weight in children may contribute to the reduction of risks of hypertension, dyslipidemia, diabetes mellitus type II¹³13 Boney CM, Verma A, Tucker R, Vohr BR. Metabolic syndrome in childhood: association with weight, maternal obesity, and gestational diabetes mellitus. Int J Pediatrics 2005; 115(3): e290-6., orthopedic disorders¹⁴14 de Mello ED, Luft VC, Meyer F. Obesidade infantil: como podemos ser eficazes? J Pediatr (Rio J) 2004; 80(3): 173-82. and psychosocial issues¹⁴14 de Mello ED, Luft VC, Meyer F. Obesidade infantil: como podemos ser eficazes? J Pediatr (Rio J) 2004; 80(3): 173-82.. In addition to individual benefits, this reduction could have a positive impact on the costs of the health system. International studies have shown that public spending on drugs to treat the complications of obesity increased from 6.5 to 9.1% from 1998 to 2006, when compared to the expenses 40% lower with non-obese subjects¹⁴14 de Mello ED, Luft VC, Meyer F. Obesidade infantil: como podemos ser eficazes? J Pediatr (Rio J) 2004; 80(3): 173-82. ^{, 15}15 Finkelstein EA, Trogdon JG, Cohen JW, Dietz W. Annual medical spending attributable to obesity: payer-and service-specific estimates. Health Aff 2009; 28(5): w822-31..

Several studies on breastfeeding have shown a protective effect on the development of child obesity. However, this relation is yet quite controversial in the literature, because of its delineations, samples and different diagnostic methods, making the comparison between them rather difficult⁹9 Simon VGN, Souza JMP, Souza SB. Aleitamento materno, alimentação complementar, sobrepeso e obesidade em pré-escolares. Rev Saúde Pública 2009; 43(1): 60-9. ^{, 10}10 Arens S, Von Kries R. Protective effect of breastfeeding against obesity in childhood: can a meta-analysis of published observational studies help to validate the hypothesis? Adv Exp Med Biol 2009; 639: 145-52. ^{, 16}16 Victora CG, Barros F, Lima RC, Horta BL, Wells J. Anthropometry and body composition of 18 year old men according to duration of breast feeding: birth cohort study from Brazil. BMJ 2003; 327(7420): 901. ^{, 17}17 von Kries R, Koletzko B, Sauerwald T, von Mutius E, Barnert D, Grunert V, et al. Breastfeeding and obesity: cross sectional study. BMJ 1999; 319(7203): 147-50..

A cross-sectional study carried out in Germany, with 9,357 children between 5 and 6 years of age, found a 4.5% prevalence of obesity among those who were not breastfed and 2.8% among the breastfed ones. The prevalence of obesity was inversely proportional to the duration of exclusive breastfeeding: at 2 months, the prevalence was 2.3%; at 3 to 5 months, 1.7%; and among those children who were exclusively breastfed for more than 12 months, it was 0.85%. The effects were adjusted for confounding factors such as social class and lifestyle, showing that breastfeeding was a protective factor against child obesity ¹⁷17 von Kries R, Koletzko B, Sauerwald T, von Mutius E, Barnert D, Grunert V, et al. Breastfeeding and obesity: cross sectional study. BMJ 1999; 319(7203): 147-50..

The objectives of this study were to verify the prevalence of excesso f weight in children under Five years of age in urban populations in Brazil, and to investigate their association with sociodemographic characteristics, exclusive breastfeeding, number of siblings and birth weight.

METHODOLOGY

To assess the access and quality of the health care system in Brazil, an epidemiological population-based survey was conducted with samples of elderly, adults and children¹⁸18 Universidade Federal de Pelotas. Acesso e qualidade na rede de saúde. 2008. Disponível em http://www.aquares.com.br (Acessado em 18 de agosto de 2009).
Disponível em http://www.aquares.com.br ... . This work refers to the sample of children under 5 years of age living in private households in the urban areas of 100 municipalities of small, medium and large size in the 5 geopolitical regions. Children hospitalized at the time of the interview were excluded.

Considering that the prevalence of child obesity is estimated at 5%¹⁴14 de Mello ED, Luft VC, Meyer F. Obesidade infantil: como podemos ser eficazes? J Pediatr (Rio J) 2004; 80(3): 173-82., 1,821 children would be required, assuming a range of error of 1 percentage point. For an overweight estimate of 15%⁶6 Silva GAP, Balaban G, Motta MEFA. Prevalência de sobrepeso e obesidade em crianças e adolescentes de diferentes condições socioeconômicas. Rev Bras Saúde Mater Infant 2005; 5(1): 53-9, with the same margin of error, 4,874 children would be necessary. In order to investigate associations with a power of 80% and a confidence interval of 95% (95%CI), with a prevalence ratio estimated at 1.6 to 3% of obesity in children with siblings and adding 10% for losses and 15% for confounding factors, the necessary sample would be 5,253 children.

The sampling process was carried out in multiple stages, using as a basis the data of the population census 2000 from the Brazilian Institute of Geography and Statistics¹⁹19 Instituto Brasileiro de Geografia e Estatística (IBGE). Metodologia do censo 2000. Ministério do planejamento. 2003. vol 25. Disponível em http://www.ibge.gov.br/home/estatistica/populacao/censo2000/metodologia/metodologiacenso2000.pdf (Acessado em 18 de setembro de 2010).
Disponível em http:... . Initially, a systematic sample of approximately 2% of Brazilian municipalities was selected. In urban areas, the number of selected sectors was proportional to the number of residential areas and to the population size.

The definition of the number of children to be located in each census area of the city (standard unit of population aggregation) has considered an average concentration of 0.34 children under 5 years of age, per household. Thus, in a sector, i.e., approximately 300 households, it was expected 102 children to be found, having chosen a sample quota of 10 children per sector, locatable in 30 households, with systematic gap of 10 households. All children under five years of age found in each of the households were included. The sample was not selected by age and 1.2 children, per household, were located.

The fieldwork took place from August to November 2008, with data collected by a team of 11 supervisors and 44 interviewers. All of them underwent a 40-hour training on techniques of household approaching and interviews and on how to standardize the collection of anthropometric data. The data were collected electronically, through a handheld computer (personal digital assistent - PDA), with specific programming for the study.

The anthropometric assessment was made using a platform scale, Geratherm^(r), with a capacity of up to 150 kg, accuracy of 0.1 kg and extendable measuring tape. The selected devices had their quality tested at the National Institute of Metrology (INMETRO) and its use authorized by the National Health Surveillance Agency (ANVISA). Both measurements were taken twice and the scale was placed in a secure and leveled place. A reading would be performed and then it would be recorded at the PDA, where the weights of the clothes were also taken note, though the interviewers were instructed to obtain measurements with as little clothes on as possible. The PDA was programmed to calculate the averages of the two measurements and to subtract the total weight of the clothes, providing, this way, the final weight of the child. For children aged two or more years, one would position the child in the center of the platform, with their feet standing together, standing up straight and with arms hanging along the body. The weight of the children under two years of age was obtained as the difference between the weight of the biological parent or guardian with and without the child in their lap.

The measuring of the height of children of two or more years of age was taken while standing up, barefoot, wearing light clothing and loose hair, on a flat surface, leaning against a wall or door, arms hanging alongside the body. A measuring tape would be extended by fixing the point zero on the ground, the reading would be made and the height would be recorded immediately afterwards. The measurement of the length of children under two years of age was performed with the child lying on a flat surface, preferably a table. The child should be barefoot, wearing light clothes and with their hair loose. With the aid of the mother, the child would be lied down, keeping their head and shoulders supported, the measuring tape then would be extended by fixing the point zero on the table. The reading would be taken and the length would be immediately recorded.

To assess the nutritional status, the growth curves of the World Health Organization (WHO)²⁰ 20 World health Organization (WHO). Development of a WHO growth reference for school age children and adolescents. Geneva; 2007. Disponível em http://www.who.int/bulletin/volumes/85/9/07-043497/en/ (Acessado em 18 de agosto de 2009).
Disponível em http:... were used, with the aid of the ANTHRO 3.1 software²¹21 World Health Organization (WHO). Multicentre Growth Reference Study Group 2006. WHO Child Growth Standards: Length/height- for age, weight-for-age, weight for length, weight for height: Methods and development. Geneva: World Health Organization; 2006. p. 312. Disponível em http://www.who.int/childgrowth/publications/en (Acessado em 12 de setembro de 2010).
Disponível em http:... . Children were considered overweight - dependent variable - when they had a Z score greater than two standard deviations above the reference average for weight and height.

The independent variables were: family income per capita (in minimum wages), maternal education (in years), skin color (caucasian and other, reported by the mother), age (in months), gender, number of siblings, birth weight (in grams) and duration of exclusive breastfeeding (up to 120 days and more than 120 days). It was considered exclusively breastfed children the ones who consumed only breast milk without any other food, water or tea.

The data analysis considered the effect of the delineation and it was made by comparing the proportions - the ^χ2 test and the calculation of the prevalence ratios - adopting 95%CI. In order to adjust the confounding factors, a logistic regression technique was used, following a hierarchical analysis model with four levels, and for the independent variable to be a part of the set model, it would require a significance of p < 0.20 in raw analysis. In the first level, the variables of per capita income, skin color, age and gender were included. The education level was not taken into account for not meeting the requirement related to the p-value. Then, on the second level, the number of siblings was analysed; in the third, the birth weight; and in the fourth level, the duration of exclusive breastfeeding.

The execution of the project had the support of the Ministry of Health, the National Council of Municipal Health Secretaries and the Municipal Councils of Health. The study was submitted to the Ethics Committee of the School of Medicine, Universidade Federal de Pelotas, being approved on November 23^rd, 2007, according to protocol 152/07. All interviewed individuals have signed a informed consent form.

RESULTS

The study included 6,397 children, of which 50% (3,195) were male and 50% (3,207) were caucasian. Each year of age gathered 20% of the sample. About 10% of the children presented low birthweight (< 2,500 grams) and 31% (1,870) of them were born weighing more than 3,500 grams. The average duration of the exclusive breastfeeding period was 120 days, 8% of the children were not breastfed and 24% were fed only breast milk until 6 months of life. Two thirds of the children belonged to families with monthly incomes of up to 0.7 minimum wages per capita (Table 1).

The prevalence of excessive weight in children younger than 5 years of age in urban population in Brazil was of 11.6% (95%CI 10.7 - 12.6). In a raw analysis, the outcome was 25% higher in males (PR = 1.25, 95%CI 1.05 - 1.50; p = 0.014). As to the age, an inverse linear association was observed: the younger the child, the greater the prevalence of excessive weight (p = 0.049). Children of 12 to 24 months of age presented an overweight prevalence 45% higher than those of four years of age or more. Caucasian children had an overweight prevalence 24% higher than non-caucasian ones (PR = 1.24, 95%CI 1.04 - 1.48; p = 0.016). No significant differences were observed as to family income.

Only children had an overweight prevalence 26% higher than the ones with siblings (PR = 1.26, 95%CI 1.04 - 1.54; p = 0.020). The higher the birth weight, the higher the prevalence of overweight, specially children who were born weighting more than 3,500 grams, with a 77% higher prevalence of excessive weight when compared to the ones born with low birth weight (PR = 1.77, 95%CI 1.25 - 2.50; p = 0.000).

As for the duration of exclusive breastfeeding, there was a 36% higher prevalence of excessive weight in children who were breastfed up to 120 days when compared to those exclusively breastfed for more than 120 days.

The adjusted analysis, according to the hierarchical model, did not reveal any significant changes in the associations found in the raw analysis. The income has completely lost its effect and the number of siblings has lost its significance. The remaining associations with gender, age, skin color, birth weight and breastfeeding remained significant after the adjustment (Table 2). For these analysis, the information of 5,195 children were used, for which all the necessary data were available.

DISCUSSION

The overall prevalence of overweight children younger than 5 years of age in urban population in Brazil was 12%, higher than the one found in the National Demographic and Health Survey of 2006⁵5 Monteiro CA, Conde WL, Konno SC, Lima AL, Silva AC, Benicio MH. Avaliação antropométrica do estado nutricional de mulheres em idade fértil e crianças menores de cinco anos. In: Brasil, Ministério da Saúde. Pesquisa Nacional de Demografia e Saúde da Criança e da Mulher: PNDS 2006: Dimensões do processo reprodutivo e da saúde da criança. Brasília; 2009. p. 213-30., which was 7.3%, indicating a possible trends towards increasing the overweight prevalence worldwide, as reported by several studies²2 Ogden CL, Flegal KM, Carroll MD, Johnson CL. Prevalence and trends in overweight among US children and adolescents, 1999-2000. JAMA 2002; 288(14): 1728-32. ^{, 5}5 Monteiro CA, Conde WL, Konno SC, Lima AL, Silva AC, Benicio MH. Avaliação antropométrica do estado nutricional de mulheres em idade fértil e crianças menores de cinco anos. In: Brasil, Ministério da Saúde. Pesquisa Nacional de Demografia e Saúde da Criança e da Mulher: PNDS 2006: Dimensões do processo reprodutivo e da saúde da criança. Brasília; 2009. p. 213-30. ^{, 6}6 Silva GAP, Balaban G, Motta MEFA. Prevalência de sobrepeso e obesidade em crianças e adolescentes de diferentes condições socioeconômicas. Rev Bras Saúde Mater Infant 2005; 5(1): 53-9 ^{, 22}22 de Oliveira AM, Cerqueira EMM, Oliveira AC. Prevalência de sobrepeso e obesidade infantil na cidade de Feira de Santana-BA: detecção na família x diagnóstico clínico. J Pediatr (Rio J) 2003; 79(4): 325-28.

23 Stamakis E, Primatesta P, Chinn S, Rona R, Falascheti E. Overweight and obesity trends from 1974 to 2003 in English children: what is the role of socioeconomic factors?. Arch Dis Child 2005: 90(10): 999-1004. ^{- 24}24 Han JC, Lawlor DA, Kimm SY. Childhood Obesity. Lancet 2010; 15: 375(9727): 1737-48.. These data should alert to the potential increase in public spending on the treatment of clinical and psychological complications of excessive weight¹²12 Spruijt-Metz D. Etiology, treatment and prevention of obesity in childhood and adolescence: a decade in review. J Res Adolesc 2011; 21(1): 129-52. ^{, 15}15 Finkelstein EA, Trogdon JG, Cohen JW, Dietz W. Annual medical spending attributable to obesity: payer-and service-specific estimates. Health Aff 2009; 28(5): w822-31..

In this study, boys had an overweight prevalence 22% higher, however, the literature is controversial regarding the risk of overweight or obesity in relation to gender²2 Ogden CL, Flegal KM, Carroll MD, Johnson CL. Prevalence and trends in overweight among US children and adolescents, 1999-2000. JAMA 2002; 288(14): 1728-32. ^{, 25}25 Mei Z, Scanlon KS, Grummer-Strawn LM, Freedman DS, Yip R, Trowbridge FL. Increasing prevalence of overweight among US low-income preschool children: the Centers for Disease Control and Prevention pediatric nutrition surveillance, 1983 to 1995. Int J Pediatrics 1998; 101(1): E12., showing a slight increase in the prevalence of overweight in girls and obesity in boys²2 Ogden CL, Flegal KM, Carroll MD, Johnson CL. Prevalence and trends in overweight among US children and adolescents, 1999-2000. JAMA 2002; 288(14): 1728-32. ^{, 26}26 Irigoyen M, Glassman ME, Chen S, Findley SE. Early onset of overweight and obesity among low-income 1- to 5-year olds in New York City. J Urban Health 2008; 85(4): 545-54. ^{, 27}27 Reilly JJ, Wilson D. ABC of obesity. Childhood obesity. BMJ 2006; 333(7580): 1207-10..

The younger the child, the greater the excess of weight. A similar result was found in a cross-sectional study conducted in New York, with a sample of 1,713 children under 5 years of age, which found a higher prevalence of overweight and obesity at ages from 1 to 3. The prevalence of overweight in these age groups increased from 3.7 to 16% and the obesity one from 7.5 to 30.2% ²⁶26 Irigoyen M, Glassman ME, Chen S, Findley SE. Early onset of overweight and obesity among low-income 1- to 5-year olds in New York City. J Urban Health 2008; 85(4): 545-54..

The prevalence of overweight among caucasian children was significantly higher than among the non-caucasian ones, even after the adjustment of confounding factors. A cross-sectional study conducted in the city of Feira de Santana, Bahia, with a sample of children from both public and private educational systems, in order to identify the prevalence of excessive weight and the perception of parents in relation to excessive weight gain, showed that the caucasian ethnic group was more associated to excessive weight²²22 de Oliveira AM, Cerqueira EMM, Oliveira AC. Prevalência de sobrepeso e obesidade infantil na cidade de Feira de Santana-BA: detecção na família x diagnóstico clínico. J Pediatr (Rio J) 2003; 79(4): 325-28., however, the literature is quite controversial regarding the influence of ethnicity as a risk factor for excess of weight in childhood²⁶26 Irigoyen M, Glassman ME, Chen S, Findley SE. Early onset of overweight and obesity among low-income 1- to 5-year olds in New York City. J Urban Health 2008; 85(4): 545-54. ^{, 27}27 Reilly JJ, Wilson D. ABC of obesity. Childhood obesity. BMJ 2006; 333(7580): 1207-10..

In this study, the household income was not associated with the outcome. However, a study carried out with 2 birth cohorts in southern Brazil in 1982 and 1993 has evidenced a direct association between obesity and income for children born in 1982, which was not sustained in the 1993 sample. Another study aiming at the evaluation of the prevalence of obesity in preschool children in São Paulo, with a sample of 957 children, showed a positive linear association with the per capita family income³3 Saldiva SR, Escuder MM, Venancio SI, Benicio MH. Prevalence of obesity in preschool children from five towns in Sao Paulo State, Brazil. Cad Saúde Pública 2004; 20(6): 1627-32.. These studies prove that the influence of family income in the prevalence of overweight is controversial. In developed countries, children who belong to low-income families present a higher prevalence for the outcome, whereas in developing countries there is evidence that the higher the income the higher the prevalence of overweight¹1 World Health Organization (WHO). Childhood overweight and obesity on the rise. 2010. Disponível em http://www.who.int/dietphysicalactivity/childhood/en/ (Acessado em 18 de setembro de 2010).
Disponível em http:... ^{, 28}28 Instituto Brasileiro de Geografia e Estatística (IBGE). Pesquisa de orçamentos familiares POF 2002-2003: análise da disponibilidade domiciliar de alimentos e do estado nutricional no Brasil. Rio de Janeiro: IBGE; 2004. ^{, 29}29 Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult populations of developing countries: a review. Bull World Health Organ 2004; 82(12): 940-6..

In the same way as the income, no association of overweight with maternal education was observed. However, when stratifying this relation according to the gender of the child, it was found that among boys the highest levels of overweight were consistent with increasing maternal education, which did not occur among girls. Further studies are needed in order to investigate if the association between higher socioeconomic status and obesity among men in adulthood³⁰30 Gigante DP, Moura EC, Sardinha LMV. Prevalência de excesso de peso e obesidade e fatores associados, Brasil, 2006. Rev Saúde Puública 2009; 43(Suppl 2): 83-9. may manifest in early childhood.

A study carried out in kindergartens of São Paulo, with a sample of 556 children from 4 to 84 months of age, showed that having 2 or more siblings was a protective factor against overweight (OR^adj = 0.28) when compared to children who had no siblings³¹31 Zollner CC, Fisberg RM. Estado nutricional e sua relação com fatores biológicos, sociais e demográficos de crianças assistidas em creches da Prefeitura do Município de São Paulo. Rev Bras Saude Mater Infant 2006; 6(3): 319-28.. In the present study, it was demonstrated that only children had a prevalence of overweight 26% higher than those who had one or more siblings, which was not confirmed in the adjusted analysis.

The birth weight was associated linearly and positively to overweight and similar results were found in a study conducted in southern Brazil, with a sample of 1,273 children, showing that the prevalence of overweight is directly proportional to birth weight³²32 Gigante DP, Victora CG, Araújo CLP, Barros FC. Tendências no perfil nutricional das crianças nascidas em 1993 em Pelotas, Rio Grande do Sul, Brasil: análises longitudinais. Cad Saúde Pública 2003; 19(Suppl 1): S141-7..

As it comes to the duration of exclusive breastfeeding until six months of age, there is evidence that this habit may protect the child from the risk of being overweight, however, longitudinal studies are needed in order to prove this hypothesis, since the literature is still controversial¹⁶16 Victora CG, Barros F, Lima RC, Horta BL, Wells J. Anthropometry and body composition of 18 year old men according to duration of breast feeding: birth cohort study from Brazil. BMJ 2003; 327(7420): 901. ^{, 17}17 von Kries R, Koletzko B, Sauerwald T, von Mutius E, Barnert D, Grunert V, et al. Breastfeeding and obesity: cross sectional study. BMJ 1999; 319(7203): 147-50. ^{, 33}33 Zive MM, McKay H, Franck-Spohrer GC, Broyles SL, Nelson JA, Nader PR. Infant-feeding practices and adiposity in 4-y-old Anglo-and Mexican-Americans. Am J Clin Nutr 1992; 55(6): 1104-8. ^{, 34}34 O'Callaghan MJ, Willians GM, Andersen MJ, Bor W, Najaman JM. Prediction of obesity in children at 5 years: a cohort study. Paediatr Child Health 1997; 33(4): 311-6. ^,.

The fact that the average duration of exclusive breastfeeding (4 months) was much higher than the one found in PNDS in 1996 and 2006, of 1.1 and 1.4 months, respectively, is noteworthy. A study showed that the initiative of Children Friendly Hospitals, with the implementation of the "ten steps to successful breastfeeding" may contribute to the increase of this average³⁵35 Perez-Escamilla R, Lutter C, Segall M, Rivera A, Trevino-Siller S, Sanghvi T. Exclusive breastfeeding duration is associated with attitudinal, socioeconomic and biocultural determinants in three Latin American countries. J Nutr 1995; 125(12): 2972-84.. It may be observed in Brazil, an increase in the duration of breastfeeding, however, the exclusive breastfeeding until the age of six months, as recommended by the WHO, is not yet a trend being followed. Some factors are determinant for exogenous obesity in childhood, such as early discontinuation of breastfeeding with introduction of inadequate complementary food³⁶36 Saldiva SRDM, Venancio SI, Gouveia AGC, Castro ALS, Escuder MML, Giugliani ERJ. Influência regional no consumo precoce de alimentos diferentes do leite materno em menores de seis meses residentes nas capitais Brasileiras e Distrito Federal. Cad Saúde Pública 2011; 27(11): 2253-62. and the improper use of infant formula diluted incorrectly³⁷37 Fisberg M, Baur L, Chen W, Hoppin A, Koletzko B, Lau D, et al. Obesity in children and adolescents: Working Group Report of the second World Congress of Pediatric Gastroenterology, Hepatology, Nutrition. J Pediatr Gastroenterol Nutr 2004; 39(Suppl 2): S678-87.. In 2006⁵5 Monteiro CA, Conde WL, Konno SC, Lima AL, Silva AC, Benicio MH. Avaliação antropométrica do estado nutricional de mulheres em idade fértil e crianças menores de cinco anos. In: Brasil, Ministério da Saúde. Pesquisa Nacional de Demografia e Saúde da Criança e da Mulher: PNDS 2006: Dimensões do processo reprodutivo e da saúde da criança. Brasília; 2009. p. 213-30. ^, the prevalence of exclusive breastfeeding in the period between birth and 6 incomplete months of age was of 38.6%, whereas in the present study it was 24%, which could be related to early introduction of foods with high caloric value, substituting breastmilk. According to the II Survey of the Prevalence of Breastfeeding in the Brazilian capitals and in the Federal District, held in 2009, there was the introduction of water, teas and other milks in 13.8, 15.3 and 17.8% of the children receiving these liquids before the first month of life, respectively³⁸38 Brasil. Ministério da Saúde. Secretaria de Atenção à Saúde. Departamento de Ações Programáticas e Estratégicas . II Pesquisa de Prevalência de Aleitamento Materno nas Capitais Brasileiras e Distrito Federal. Brasília; 2009. Disponível em http://bvsms.saude.gov.br/bvs/publicacoes/pesquisa_prevalencia_aleitamento_materno.pdf (Acessado em 18 de fevereiro de 2011).
Disponível em http:... . Longitudinal studies which cover eating habits and lifestyle of the family are required as to establish prevention and control measures from the actual data.

It is stressed in this study some positive factors, such as: the quality of data collection in electronic media (PDA), making the fieldwork more dynamic and reliable, the size of sample capable of establishing the prevalence measures, association and nationwide power.

The use of a measuring tape is no longer appropriate for the anthropometric assessment, since reading difficulties could occur. For this, there was a special caution when performing all measurements in duplicate, to reduce the possibility of measurement errors. It is known that population-based studies are laborious, for they usually consist of large samples, in difficult accessing locations, where the use of heavy equipment makes the execution of it rather difficult.

This study concludes that the prevalence of excess weight in children appears very elevated in urban areas in Brazil, being higher in boys, in children under one year of age, caucasian, with birth weight greater than 3,500 grams and who were exclusively breastfed for less time. The adoption of measures which encourage healthy eating habits and physical activity from an early age is recommended, and within the health system, the special attention of teams in the dealing and the treatment of overweight children, making the family aware of the need for a change in the habits of everyone and not just the child's¹⁴14 de Mello ED, Luft VC, Meyer F. Obesidade infantil: como podemos ser eficazes? J Pediatr (Rio J) 2004; 80(3): 173-82. ^{, 39}39 Brasil. Ministério da Saúde. Ministério do Planejamento, Orçamento e Gestão . Pesquisa de orçamentos familiares 2008-2009. Antropometria e estado nutricional de crianças, adolescentes e adultos no Brasil. Rio de Janeiro: IBGE; 2010..

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