Measures of reliability and validity of three constructs of the Theory of Planned Behavior applied to exclusive breastfeeding maintenance behavior

Abstract

Despite benefits of breastfeeding to infants and mothers, a large decrease in exclusive breastfeeding (EBF) rates from birth to 6 months (59% to 11.3%) suggests that reasons for initiation and maintenance behaviors may be different. The aim of this study was to measure the reliability and validity of three constructs of the Theory of Planned Behavior (TPB) applied to the EBF maintenance behavior. A questionnaire was constructed to assess the constructs of the theory: attitude toward the act (AA), subjective norm (SN), and perceived behavioral control (PBC). Fifteen items were developed from formative research using elicitation technique to measure theses constructs. The questionnaire was self‐administered to a convenience sample of 78 volunteer mothers, who had initiated EBF and were less than 4 months postpartum, between May and Oct, 2006 in Central Indiana. Internal consistency and factor analysis were performed to assess the reliability and construct validity of these three constructs. The reliabilities were found to be acceptable: 0.84(AA), 0.60 (SN), and 0.90 (PBC). A factor analysis revealed three distinct theoretical constructs that accounted for 77% of the total variance of the items. Findings support the use of these measures in TPB‐based studies to examine the relative importance of the determinants of EBF maintenance for six months, thereby providing direction for future EBF maintenance programs.