This is a cross-sectional study of anthropometric data in preschool children from 14 daycare centers linked to the Department of Health and the Federation of charities (FEAS) in Santo Andre, SP, Brazil. The data collection was performed between 2001 and 2002. Santo Andre is a city with approximately 600,000 inhabitants and a total of 43 daycare centers. The Department of Health and the FEAS develop systematic surveillance activities to children's health enrolled in day care centers. The project was undertaken in partnership between the day care centers and the public system. This study was explained to the parents or guardians responsible for the child and it was begun only after his or her consent according to the standards of the committees of research and ethics. All experimental procedures were in compliance with the Helsinki Declaration. The study was approved by the Ethics Committee in Research of the Faculdade de Medicina da Universidade de São Paulo (FMUSP, number 923/00).
The study population included 1639 children aged between 2 and 6 years old, all from low income families. We excluded 95 (5.8%) because they were not of preschool age, hence, it remained 840 (54.4%) boys and 704 (45.6%) girls from a total of 1544 children (Table ). We also excluded children who presented congenital diseases, history of nutritional and metabolic diseases, chronic diseases that could influence their growth and those who did not agree to collect data. This information was collected during the interview. According to the government (http://www2.santoandre.sp.gov.br/
), this population represents a proportion of approximately 40% of all children from 2 to 6 years old from Santo Andre. We observed average monthly income per capita (AMPC) of 0.55 minimum wages (MW - ~U$175.00), the average number of persons per house was 4.6, the median years of mother schooling was 6 years and the median years of father schooling was 5 years. Half of the parents worked in trades such as unskilled and 15% were unemployed (Table ).
Children distribution according to gender and age
Distribution of children parents enrolled in day care centers according to occupation*
Weight (W) and height (H) were measured by researchers using internationally accepted techniques [19
] under supervision of pediatricians from the daycare centers and all data were collected from records of child care using a standardized form. Anthropometric data were collected in the daycare center, according to Lohman et al [20
] method. The child's weight was measured by using the Seca®
electronic scale with a split of 0.1 g, and height was measured by stadiometer wall (Seca®
) with two meters and centimeters and millimeters subdivision [21
]. In addition to weight and height we included the following variables: age, gender, birth weight, duration of breastfeeding, maternal age at child birth, level of maternal education, AMPC and how long they had attended the daycare center. Scales and stadiometers were calibrated regularly and reliably.
The values of W, H and body mass index (BMI) were transformed into z scores and percentiles based on the National Center for Health Statistics - 2000 (CDC/NCHS) framework and it was statistically analyzed in relation to the distribution and the association with socio-demographic and health data.
The cutoff points for nutritional disorders analysis were: -2 z scores and 2.5 and 10 percentiles for risk of malnutrition, 85 to 95 percentile for overweight and above the 95 percentile for obesity [22
Data were stored in an Excel® worksheet. In order to calculate anthropometric indices we used the software EpiInfo 3.3.2 Nutrition February 2005, which described the frequency distribution and central tendency measures (mean, standard deviation and median). Pearson's coefficient was used to evaluate the correlation between age and anthropometric indices.
The analysis was performed by the Stepwise Backward Regression method including the following variables: age, gender, birth weight, duration of breastfeeding, age of mother at birth and how long they had attended the daycare center which in univariate analysis showed a p < 0.15 in the evaluation of its association with excess weight (overweight and obesity, evaluated by z score of BMI). In order to verify if the proposed regression model fits the data well, we applied the F-test.
The level of significance (α) adopted for all statistical tests was 5%. The statistical processing of data was performed with SPSS ® 12.0.