BackgroundBreastfeeding plays a major role in the health of mothers and babies and has the potential to positively shape an individual’s life both in the short and long-term. In the United Kingdom (UK), despite around 81% of women initiating breastfeeding, only 1% of women breastfeed exclusively to 6 months as recommended by the World Health Organisation (WHO). Women who are socially disadvantaged and younger, are less likely to breastfeed at 6-8 weeks postpartum. One strategy that aims to improve these statistics is the Baby Buddy app which has been designed, developed and implemented by the UK charity Best Beginnings to be a universal intervention to help reduce health inequalities, including breastfeeding. The aim was this study was to retrospectively examine the development of Baby Buddy as a Digital Behaviour Change Intervention (DBCI) that may increase breastfeeding self-efficacy, knowledge and confidence to positively impact breastfeeding rates and duration.MethodsThe study used a three-stage process evaluation, triangulation methods and formalised tools. A retrospective evaluation was done after the app was developed and embedded. The app development process and content were reviewed by applying the Behaviour Change Wheel (BCW), Capability, Opportunity and Motivation-Behaviour (COM-B) system and Behaviour Change Techniques Taxonomy (BCTTv1). A clear understanding of behaviours that need to change in pregnancy to improve breastfeeding knowledge, self-efficacy and confidence was sought. ResultsRetrospective application of the BCW, COM-B and BCTTv1 confirmed that the Baby Buddy app is a well-designed DBCI, appealing particularly to younger women and women for whom English is not their first language. The Best Beginnings charity used several frameworks and guidelines and the use of these instruments contributed to the good design and development of Baby Buddy. Content analysis verified that the resources developed could affect attitudes and assist women to make decisions, and perceptions of self-efficacy in relation to breastfeeding. ConclusionsBaby Buddy has the potential to improve breastfeeding knowledge, confidence and self-efficacy. Future research should assess which components of the app are most effective on breastfeeding and whether it has an impact on clinical health outcomes for mothers and babies.