What modifiable factors positively influence breastfeeding duration to 6 months postpartum? This question was posed in order to be able to develop a midwifery intervention aimed at prolonging breastfeeding. An online literature search was conducted in Medline, CINAHL, Maternity and Infant Care, and Cochrane Database of systematic reviews. The search strategy included the following keywords: breastfeeding, duration, initiation, cessation, factors, intervention, education, partner, intention, confidence, self-efficacy and support. Additional studies were located and extracted from online publications of New South Wales Department of Health, Australia. Bio-psycho-social factors that are positively associated with breastfeeding duration were identified. Modifiable factors that influence women's breastfeeding decisions are: breastfeeding intention, breastfeeding self-efficacy and social support. Existing midwifery breastfeeding promotion strategies often include social support but do not adequately address attempts to modify breastfeeding intention and self-efficacy. The modifiable factors that are positively associated with breastfeeding duration are the woman's breastfeeding intention, her breastfeeding self-efficacy and her social support. Intervention studies to date have focussed on modifying these factors individually with variable results. No interventional studies have been conducted with the aim of positively modifying all three factors simultaneously.