To investigate the determinants of mild-to-moderate malnutrition in preschoolers.

Cross-sectional study conducted in October and November 1996, with a representative sample of 1740 children less than 5 years old from the city of Salvador, situated in the Brazilian Northeastern region. Socio-economic and dietary data were collected through a structured questionnaire. Anthropometric measures were performed in duplicate and data analysis was based upon the hierarchical model approach. Logistic regression analysis was used to estimate the prevalence ratio and to identify the determinants of mild-to-moderate deficits in weight-for-age and height-for-age Z-scores.

Family monthly income under US$67.00 per capita and family headed by a woman were the main basic determinants of mild-to-moderate weight-for-age and height-for-age deficits in the studied children. Household agglomeration, an underlying determinant, was associated with weight-for-age and height-for-age deficits. Among the immediate determinants, age above 6 months and dietary caloric availability in the lowest tertile (<930 kcal day−1) were also associated with weight-for-age deficits. In addition to these, hospitalisation in the 12 months preceding the interview was shown to be a predictor of mild-to-moderate weight-for-age and height-for-age deficits.

Adverse social and economic factors interact with family environmental factors to define food consumption and morbidity patterns that culminate in a high prevalence of mild-to-moderate malnutrition. The strengthening and restructuring of nutrition and healthcare actions, the definition of public policies that improve family income, and the adequate insertion of women in the labour market are possible strategies to reduce mild-to-moderate malnutrition and to sustain the decline already observed in severe malnutrition.