Development of a questionnaire to assess maternal attitudes towards infant growth and milk feeding practices

BACKGROUND: There is increasing recognition that public health strategies to prevent childhood obesity need to start early in life. Any behavioural interventions need to target maternal attitudes and infant feeding practices, This paper describes the development and preliminary validation of a questionnaire to assess maternal attitudes towards infant growth and milk feeding practices. METHODS: We designed a 57-item (19 questions), self-administered questionnaire to measure the following four domains- 1) type of milk feeding, decision making and sources of advice; 2) frequency and quantity of milk feeds; 3) attitudes to infant feeding and growth; and 4) theory-based beliefs about following infant feeding recommendations. Forty mothers completed the questionnaire on two occasions six days apart (to assess test-retest reliability) and then participated in a semi-structured, open-ended telephone interview covering the same domains (to assess criterion validity). Percentage agreement, Cohen's Kappas (for categorical variables) and Spearman's correlation coefficients (for continuous variables) were used to quantify reliability and validity. Internal consistency between theory-based constructs (self-efficacy, outcome expectancy and intention) was quantified by Chronbach's alpha. RESULTS: Of the 57 questionnaire items 51 (89%) had percentage agreement above 70% indicating good test-retest reliability, and the remaining 6 items had moderate or substantial levels of agreement (kappa 0.41-0.68). Comparing questionnaire with interview coding (validity), percentage agreement was above 66% for 39/57 items (68%). Of the 16 items with percentage agreement below 66%, only five had kappa values below 0.20 (two items had insufficient interview responses). Internal consistency was 0.51, 0.79 and 0.90 for self-efficacy, outcome expectancy and intention respectively. CONCLUSIONS: This questionnaire could be a useful tool in understanding the determinants of infant feeding and the 'causal mechanism' of interventions that target infant feeding practices to prevent early obesity.