Abstract
Breastfeeding has many known benefits, but rates vary globally. We propose two main reasons why psychological theory and interventions have not been successful to date in explaining breastfeeding behaviours. Specifically, prior research underestimates the importance of (1) specific emotions and (2) wider injunctive influences (i.e., societal and moral norms about what women feel they ought to be doing) in the breastfeeding experience. Therefore, we conducted a systematic review of quantitative, qualitative, and mixed-methods studies that explored whether injunctive norms and/ or specific emotions are associated with breastfeeding behaviours (i.e., intentions, initiation and duration). Seventy-two papers were included in this review; data were extracted and quality appraisals conducted for all included studies. A meta-analysis of effect sizes was performed with the quantitative data. A convergent qualitative synthesis of the data was conducted, resulting in the following line of argument: Breastfeeding is a social behaviour and not a personal/individual behaviour. From this line of argument, three themes with associated sub-themes were developed, highlighting the importance of both specific emotions and injunctive norms on breastfeeding behaviours. These influences are discussed in relation to both theoretical and practical implications, as well as future research.