Breastfeeding is a global public health priority and a recommended health behaviour worldwide. The World Health Organisation (2003) recommends early initiation of breastfeeding, exclusive breastfeeding for the first six months of life, and extended breastfeeding for up to two years and beyond to support optimal child health and development. The health benefits of breastfeeding are well-substantiated, but prevalence rates worldwide remain low and breastfeeding rates rapidly decline across the postpartum period. In the United Kingdom, breastfeeding rates are amongst the lowest in the world (McAndrew et al., 2012). Infant feeding outcomes are yet to be explored among infants born with a larger birthweight i.e. macrosomic (birthweight t4,000g or 4,500g) or large-forgestational age (>90th or 95th centile on growth charts). The benefits of breastfeeding may be particularly valuable for these infants over the life course. Therefore, the overarching aim of this PhD was to explore perceptions and practices of infant feeding among women who give birth to healthy, full-term larger birthweight infants (birthweight t4,000g) to identify potential priority targets for future breastfeeding support strategies. To address limitations with previous research, this thesis assimilated approaches from the Theory of Planned Behaviour (Ajzen, 1991), Self-Efficacy Theory (Bandura, 1997) and the Capability-Opportunity-Motivation and Behaviour model (Michie et al., 2011) to provide a more comprehensive framework for exploring breastfeeding as a health behaviour. Theoretical and methodological considerations of measuring breastfeeding as a health behaviour were also explored. A proportional measure of infant feeding was proposed to more accurately capture infant feeding practices throughout this body of work. A psychometric evaluation of the Beliefs About Breastfeeding Questionnaire (BAB-Q) identified it was a reliable measure to capture women’s beliefs and appraisals of the benefits and efforts associated with breastfeeding. However, the utility of the BAB‐Q at predicting breastfeeding behaviour remains unsupported by empirical evidence. An embedded mixed-methods design was used to assimilate quantitative and qualitative research methods and design empirical studies to address four main research objectives. This thesis presents findings from a longitudinal cohort study with two embedded qualitative interview studies to explore perceptions and practices of infant feeding among women who gave birth to larger birthweight infants. The longitudinal cohort study recruited women in their third trimester of pregnancy from hospital and community settings who were followed to four months postpartum. A total of 328 women who gave birth to 224 average birthweight (t2,500g <4,000g) and 104 larger birthweight (t4,000g) infants were included in the final study sample. Adjusted longitudinal logistic regression models assessed the likelihood of breastfeeding at four timepoints postpartum: birth, two weeks, eight weeks and four months. Women with larger birthweight infants were more likely to exclusively breastfeed at birth (aOR = 1.94, 95%CI 0.90, 4.18, p = .089) and two weeks postpartum (aOR= 2.13, 95%CI 1.11, 4.06, p = .022) than women with average birthweight infants. There were no statistically significant associations between birthweight and breastfeeding at eight weeks or four months postpartum. A larger infant birthweight may increase the likelihood of exclusive breastfeeding in the early postpartum period. Longitudinal ordinal logistic regression analyses considering relevant demographic and clinical variables alongside psychosocial factors identified stronger desires for breastfeeding, weaker desires for formula-feeding, increased breastfeeding self-efficacy, more vicarious experience of formula-feeding, and increased fears about nutrition were associated with increased likelihood of breastfeeding across the postpartum period. Exploring psychosocial factors associated with breastfeeding between women with larger and average birthweight infants revealed perceptions and experiences of infant feeding were comparable over time. Overall, findings suggest a larger infant birthweight may not elicit a unique psychological response towards infant feeding practices, and is unlikely to have an independent effect on breastfeeding across the postpartum period. Further investigation was necessary to understand why women who gave birth to larger birthweight infants appeared to be more likely to breastfeed in the early postnatal period. Two qualitative interview studies were conducted to compare experiences of breastfeeding between women who gave birth to larger and average birthweight infants. Grounded Theory provided a suitable methodology to generate a theoretical explanation for the phenomenon of interest (e.g. breastfeeding behaviour) in a particular context (e.g. women with healthy, full-term average birthweight infants). The theory developed in the context of average birthweight infants was then applied to a new context (i.e. women with healthy, term, larger birthweight infants) and ‘tested’ to understand whether observations and patterns were distinct. Among women who gave birth to average birthweight infants, three distinct themes were found: Perceived indicators of ‘good’ feeding (infant ‘output’; infant crying; weight gain; feeding frequency and duration); Women’s experiences of breastfeeding latch (‘good’ latch; ‘bad’ latch with pain and discomfort); and Overall breastfeeding experience (positive; negative; and uncertain). These themes were understood to be related in a mediated pathway analysis, where three types of overall feeding experience could be achieved through four distinct pathways. Women seemed to give precedent to their experience of breastfeeding latch, such that a painful or uncomfortable latch could outweigh perceived cues of ‘good’ feeding or feeding sufficiency and lead to women having a negative experience of breastfeeding overall. Study findings demonstrated that even among healthy women with healthy, full-term infants, a positive breastfeeding experience without uncertainty or pain was difficult to achieve. Theoretical explanations of breastfeeding experiences among women with average birthweight infants were not found to hold true in the context of larger birthweight infants. To explain experiences of breastfeeding among women with larger birthweight infants a new theory was proposed grounded in the data available, and comprised three distinct themes: Infant Ability to Breastfeed (latch; signs of satiety; milk supply), Attenuating Maternal Concerns (feeding frequency; Weight Loss; Overfeeding), and Reality of Breastfeeding (expectations of feeding; adjustment to the feeding role; self-doubt and hard work). Women with larger birthweight infants did not experience persistent difficulties with breastfeeding latch or lactation, and attributed infant’s as having ability to breastfeed. Women also did not experience the same degree of worry (e.g. about milk supply, weight gain/loss, or feeding patterns) as observed among women with average birthweight infants. Overall, findings suggested a larger infant birthweight could potentially protect against breastfeeding difficulties and was associated with alleviating maternal concern. In terms of overall experience, breastfeeding may be easier for women with larger birthweight infants, in comparison to the observed experiences of women with average birthweight infants, but that did not mean breastfeeding was easy for women. Findings from the cohort study and interview studies identified key factors associated with breastfeeding, which could be potential priority targets when considering intervention strategies. To understand how the findings of this research could be implemented in policy in practice, there was a need to consider how these key factors could be targeted and changed with intervention to improve breastfeeding rates. A systematic review and meta-analysis was conducted to evaluate the effectiveness of social and psychological-based interventions designed to improve breastfeeding practices. As perceptions and experiences of infant feeding were not systematically different between women who gave birth to larger and average birthweight infants, effectiveness of interventions including women who gave birth to healthy, full-term infants (regardless of birthweight) were explored. Meta-analytic results suggested that while interventions using behaviour change techniques could increase the proportion of women who start breastfeeding (N = 2,213; OR = 2.32, 95% CI [1.33, 4.03], p = .003), they were not effective at increasing the proportion of women who maintained partial (N = 4,153; OR = 0.88, 95% CI [0.72, 1.09], p=.253) or exclusive (N = 3671; OR=0.85, 95% CI [0.53, 1.36], p=.469) breastfeeding up to six months postpartum. Evaluation of the evidence also identified that many of the breastfeeding promotion interventions delivered at an individual-level typically did not theorise how the strategies and techniques used were meant to change behaviour. Overall, evidence presented in this thesis found women who gave birth to larger birthweight infants may be more likely to breastfeed exclusively in the early postnatal period. Qualitative evidence suggested a larger infant birthweight could facilitate breastfeeding establishment and protect against early latch and lactation difficulties. However, when considered alongside additional clinical, psychological and social factors, evidence available indicates a larger infant birthweight is unlikely to have a significant or sustained independent effect on how women feed their infants over time. Findings from studies across this body of work helped to highlight that women who give birth to healthy, full-term larger birthweight infants are unlikely to require specialised breastfeeding counselling that differs from effective support already available. Models of health behaviour have guided investigations throughout this research, which have helped to identify some potential priority targets for support that could be considered in future research, intervention, and healthcare policy. Prioritising breastfeeding as a health behaviour would help to better understand breastfeeding as a complex and dynamic behaviour that is part of a wider behavioural system.
| Date of Award | 1 Apr 2021 |
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| Original language | English |
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| Awarding Institution | |
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| Supervisor | Joseph Chilcot (Supervisor) & Debra Bick (Supervisor) |
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