1. BACKGROUND Since the early 1990’s, breastfeeding has been on the global public health agenda, yet breastfeeding rates remain low. The UK performs particularly poorly; while 73% of women initiate, only 47.3% are still breastfeeding at 6-8 weeks. Despite this, many women report a desire to breastfeed for longer. With extensive promotion of ‘Breast is Best,’ it is difficult to argue that low rates are driven by a lack of knowledge about the health benefits of breastfeeding. Low levels of social support is increasingly targeted in initiatives to improve breastfeeding outcomes; however, it may well be that the public health messaging itself, and the medicalised discourse around breastfeeding, also requires review. Current messaging focuses on the health benefits to infants, expecting women to breastfeed out of moral duty and stigmatising those who do not. Breastfeeding is a learnt behaviour and problems are common; however, by framing it as “natural” and omitting information about problems, public health messaging leaves women who struggle feeling unprepared, abnormal and isolated. Stigma and the lack of preparation for the challenges, are likely having a negative impact on women’s feeding experience and, ultimately, their breastfeeding success. Previous methodological issues, however, mean we do not fully understand these relationships. While qualitative studies have collected extensive, rich and crucial data on the lived experience of infant feeding, sample sizes are relatively small limiting generalisations. Quantitative studies have larger samples, yet are often cross-sectional, lacking detailed information on feeding journeys. While a handful of prospective studies (mainly qualitative) are available, the chaotic nature of the early weeks postpartum leads many researchers to create retrospective study designs, interviewing women several weeks or months later, producing reporting biases. This may be particularly problematic for studying feeding practices; women’s experiences shift over time and self-narratives may be rewritten, making the factors influencing feeding decisions difficult to capture retrospectively. Finally, samples are often biased towards more affluent women who have more time and capacity to respond to surveys. Overall, these methodological limitations create challenges in uncovering population-level causal pathways behind low breastfeeding rates. Here we propose to address these limitations by engaging a large number of diverse women from London in their pregnancy and prospectively tracking their infant feeding journeys using an innovative new methodology. 2. AIMS AND RESEARCH QUESTIONS Large-scale, quantitative descriptions tracking women’s infant feeding journeys are lacking, and their production requires fresh methodological approaches. This project, focused on mothers from London in the first instance, will develop and pilot a novel data collection method where mothers can document their own infant feeding journeys through a user-friendly app. Complimented by user experience data to inform future app updates, we will lay the foundations for reliably unpicking the relationships between infant feeding expectations, experience and decisions over time among potentially unlimited numbers of women in the future. Overall, this project has three interwoven aims: 2.1. AIM ONE: Develop an innovative, user-friendly app which engages a larger, more representative sample of women to report real-time experiences of their feeding journeys Inspired by epidemiological studies which currently use app-based methodologies, we seek to develop an app to collect daily information on infant feeding, entailing minimal user time and effort. To ensure user engagement, we will design the app to allow the users to track, visualise and summarise their own feeding journeys (including graphical functions and records of problems and experiences to structure interactions with health professionals). This aim will be assessed by the degree of user engagement (how many initial downloads, how many users report experiences daily) as well as how socio-demographically diverse our sample is. 2.2. AIM TWO: Pilot and gain feedback on the app before large-scale data collection This project will enable initial piloting of the app, which will form the basis of a later UK-wide roll-out, and large-scale data collection. Collecting user-feedback via survey and focus groups, will enable us to address any issues and increase usability before a large-scale launch – which will lead to lower attrition, better data quality and improved user experience. To meet this aim we will address three research questions: 1A) Did women find it easy and quick to use the app; 1B) What else would they find useful within the app; 1C) How did women engage with the app on a daily basis? These questions will form the basis of a methodological paper about participant-led, app-based data collection in the social sciences. 2.3. AIM THREE: To examine changing expectations and experiences through the infant feeding journeys of pilot participants Due to aforementioned methodological issues, the causal relationships between ideology, expectation, experience and breastfeeding continuation remain unknown. Our prospective study design means we can explore how women move between feeding modes, as well the experiences of those who do not initiate breastfeeding. To meet this aim we will conduct a preliminary exploration of the app data framed around three research questions: 2A) How does mode of feeding and women’s feelings about infant feeding change overtime; 2B) how do prior expectations influence feeding experiences and; 2C) how well do women’s breastfeeding experiences predict their likelihood of (exclusive and any) breastfeeding to six weeks, moderated by social support and expectation? These questions will be discussed in a theoretical paper on infant feeding expectations and experiences, and the consequences of this in breastfeeding duration. 3. SUMMARY Previous research has not documented the changing and temporal nature of women’s infant feeding experiences on a large-scale. Many women find infant feeding challenging and stressful, perhaps due to medical and social discourse around breastfeeding. However, methodological limitations constrain understandings of the causal pathways underlying maternal feeding decisions. This project will directly contribute to debates surrounding infant feeding by developing and piloting an innovative app for prospectively documenting infant feeding journeys in a large-scale and quantitative fashion.