Health outcomes related to infant feeding in the Republic of Ireland and Northern Ireland: A scoping review protocol

Edina Hanley; Jane Bourke; Jennifer Hanratty; Elaine Lehane; Helen Mulcahy; Róisín O'Donovan; Aoife Long; Margaret Murphy; Karen Matvienko-Sikar; Siobhan Ward; Patricia Leahy-Warren

doi:10.12688/hrbopenres.14291.1

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Study Protocol

Health outcomes related to infant feeding in the Republic of Ireland and Northern Ireland: A scoping review protocol

[version 1; peer review: awaiting peer review]

Edina Hanley ¹^*, Jane Bourke²^*, Jennifer Hanratty³, [...] Elaine Lehane¹, Helen Mulcahy¹, Róisín O'Donovan¹, Aoife Long¹, Margaret Murphy¹, Karen Matvienko-Sikar⁴, Siobhan Ward⁵, Patricia Leahy-Warren¹

Edina Hanley ¹^*, Jane Bourke²^*, [...] Jennifer Hanratty³, Elaine Lehane¹, Helen Mulcahy¹, Róisín O'Donovan¹, Aoife Long¹, Margaret Murphy¹, Karen Matvienko-Sikar⁴, Siobhan Ward⁵, Patricia Leahy-Warren¹

^* Equal contributors

PUBLISHED 23 Jan 2026

Author details Author details

¹ School of Nursing and Midwifery, Brookfield Health Sciences Complex,University College Cork, Cork, County Cork, Ireland
² Department of Economics, Cork University Business School, University College Cork, Cork, County Cork, Ireland
³ Centre for Effective Services, Dublin, Leinster, Ireland
⁴ School of Public Health, University College Cork, Cork, County Cork, Ireland
⁵ La Leche League International, Dublin, Ireland

Edina Hanley
Roles: Conceptualization, Methodology, Project Administration, Writing – Original Draft Preparation, Writing – Review & Editing

Jane Bourke
Roles: Conceptualization, Funding Acquisition, Methodology, Supervision, Writing – Original Draft Preparation, Writing – Review & Editing

Jennifer Hanratty
Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing

Elaine Lehane
Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing

Helen Mulcahy
Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing

Róisín O'Donovan
Roles: Conceptualization, Methodology, Writing – Review & Editing

Aoife Long
Roles: Conceptualization, Methodology, Project Administration, Writing – Review & Editing

Margaret Murphy
Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing

Karen Matvienko-Sikar
Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing

Siobhan Ward
Roles: Writing – Review & Editing

Patricia Leahy-Warren
Roles: Conceptualization, Funding Acquisition, Methodology, Supervision, Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS AWAITING PEER REVIEW

Abstract

Introduction

Breastfeeding supports infant health and reduces healthcare utilisation. However, breastfeeding rates in Ireland remain lower than recommended by the World Health Organisation. Formula feeding has been associated with increased risks of common childhood illnesses such as respiratory infections, gastrointestinal infections and otitis media. Understanding the health outcomes related to breastfeeding and formula feeding in the Irish context is essential to inform cost analyses, policy development and investment in breastfeeding support.

Objective

To understand the extent and nature of evidence on infant and child health outcomes related to infant feeding practices in Ireland, in order to inform recommendations for a national cost analysis. We are building on previous international reviews, specifically Renfrew et al. (2012) and Onah et al. (2025). Onah et al. (2025)’s investigation on the costs of suboptimal breastfeeding in Ontario, Canada was structured around three key evidence reviews. The second review/review B identified Canadian studies examining infant feeding and health outcomes (Onah et al., 2025). This protocol outlines how we will undertake review B for Ireland and Northern Ireland.

Methods

CINAHL (EBSCO) and PubMed will be searched. Controlled, experimental or epidemiological (analytic or observational) studies that analyse the relationship between breastfeeding and/or formula feeding and infant and child health outcomes and include participants from Ireland (Republic of Ireland and Northern Ireland) will be included. A grey literature search will be undertaken on Google Scholar and Lenus. Case reports, case series and papers not reporting a study will be excluded.

The reference lists of the included studies will be searched. No restrictions will be used. Titles and abstracts and full-text articles will be screened by two independent reviewers. All authors will agree on the included studies. Data will be extracted and presented graphically using figures and tables. Narrative summary text will accompany the tables and figures.

Keywords

Breastfeeding; Child Health Outcomes; Infant Feeding; Infant Health Outcomes; Ireland; Northern Ireland

Corresponding authors: Edina Hanley, Jane Bourke

Competing interests: No competing interests were disclosed.

Grant information: Health Research Board -APRO-2023-015. This review is being undertaken as part of the ‘Maximise support for breastfeeding for sustainable population health and wellbeing: Integrated knowledge translation approach, MaxSBF’ and is funded by the Health Research Board.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright: © 2026 Hanley E et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: Hanley E, Bourke J, Hanratty J et al. Health outcomes related to infant feeding in the Republic of Ireland and Northern Ireland: A scoping review protocol [version 1; peer review: awaiting peer review]. HRB Open Res 2026, 9:13 (https://doi.org/10.12688/hrbopenres.14291.1) First published: 23 Jan 2026, 9:13 (https://doi.org/10.12688/hrbopenres.14291.1) Latest published: 23 Jan 2026, 9:13 (https://doi.org/10.12688/hrbopenres.14291.1)

Introduction

The World Health Organisation (WHO, 2023) recommend breastfeeding for a minimum of two years of life and that the first six months be exclusive breastfeeding and in combination with the family diet, thereafter, supporting optimal growth, development, and health. The global exclusive breastfeeding target is to increase the rate of exclusive breastfeeding during the first six months of life to at least 50% by 2025 (WHO, 2014) and 70% by 2030 (WHO, 2018). The Republic of Ireland’s breastfeeding rates remain amongst the lowest worldwide and in Europe (World Breastfeeding Trends Initiative, 2023), and Northern Ireland has the lowest rates of breastfeeding in the United Kingdom (HSC Public Health Agency, 2024). Breastfeeding at birth in the Republic of Ireland is 64%, and 62.2% in Northern Ireland. At discharge, rates decline to 61.3% and 50.3%, respectively. By three months, breastfeeding rates fall further to 42% in the Republic of Ireland and 29.3% in Northern Ireland. Exclusive breastfeeding rates at discharge are 36.9% in the Republic of Ireland and 37.3% in Northern Ireland and exclusive breastfeeding rates at three months decrease to 32% in the Republic of Ireland and 22.4% in Northern Ireland (Health Service Executive, 2023; HSC Public Health Agency, 2024).

The benefits of breastfeeding for infant and child health are well recognised (Horta & Victora, 2013; Murphy et al., 2023; Victora et al., 2016). Breastfeeding is associated with a reduced risk of several paediatric health conditions which can translate into clinical and economic costs. Breastfeeding may protect against respiratory illnesses, gastrointestinal infections, diarrhea, otitis media, necrotizing enterocolitis (NEC) in preterm infants and obesity later in life (Victora et al., 2016). The findings reported by a study undertaken in the Republic of Ireland demonstrate an association between breastfeeding and both infant morbidity and healthcare utilisation (Murphy et al., 2023). Murphy et al. (2023) estimated that there would have been approximately 17,766 less nights in hospital if all infants had been exclusively breastfed for at least 90 days, compared to none of these infants being breastfed. A meta-analysis by Bachrach et al. (2003) reported a 72% reduction in the risk of hospitalisation for respiratory illness among infants exclusively breastfed for at least four months compared to formula fed infants in developed settings. Thus, exclusive breastfeeding can reduce healthcare utilisation and associated costs. The current review will consider both breastfeeding and formula feeding and associated infant and child health outcomes in Ireland.

The economic case for investing in breastfeeding has been demonstrated (Hui et al., 2025; Murphy et al., 2023; Renfrew et al., 2012). Suboptimal breastfeeding rates result in increased costs for children, families and healthcare systems (Onah et al., 2025). Health benefits associated with breastfeeding are present in the short, medium and long term (McGovern et al., 2018). Identifying the health outcomes related to infant feeding at a national level is important for service and policy development. Identifying and understanding the health outcomes and illnesses associated with feeding practices may inform tailored interventions required to improve infant and child health outcomes.

A preliminary search for existing reviews on this topic was conducted on Epistomonikos, PROSPERO and Google Scholar on the 31^st of July 2025. A cost analysis by Onah et al. (2025) was identified. Onah et al. (2025) updated and applied the approach by Renfrew et al. (2012) to examine the economic impacts of suboptimal breastfeeding in Canada. This involved updating the reviews undertaken by Renfrew et al. (2012). Review A (Onah et al., 2025) focused on reviews examining the association between breastfeeding and paediatric health and cognitive outcomes in high-income countries. Review B (Onah et al., 2025) focused on Canadian studies examining health outcomes associated with breastfeeding to contextualise the economic model. Review C (Onah et al., 2025) synthesized cost-of-illness studies related to infant feeding from comparable high-income settings and informed their overall approach (Onah et al., 2025). The Canadian cost analysis included seven infant pathologies: lower respiratory tract infections, gastrointestinal infections, acute otitis media, NEC, childhood obesity, childhood acute lymphoblastic leukaemia (ALL), and childhood asthma (Onah et al., 2025).

The purpose of this review is to support an Irish cost analysis of health care utilisation linked to the seven infant pathologies, identified by Onah et al. (2025), that may be reduced through higher breastfeeding rates. This scoping review will identify studies in Ireland on health outcomes associated with different types of infant feeding (i.e. undertaking Review B in Onah et al., 2025 for Ireland). Unlike Onah et al. (2025)’s Review B of Canadian studies, our scoping review will also include formula feeding. As many babies in Ireland receive formula milk during the initial weeks postpartum (Tarrant et al., 2012). This will help to ensure that all relevant infant feeding evidence is identified in Ireland.

Objective

The objective of this scoping review is to identify and describe Irish evidence on infant health outcomes associated with infant feeding practice for infant pathologies. The findings will inform a cost analysis of feeding practices and health outcomes in Ireland, drawing on methods used in Renfrew et al. (2012) and Onah et al. (2025) studies. While health outcomes associated with breastfeeding is a key focus of the current review, formula feeding will be included to support a broader comparative analysis of illness-related costs across different feeding methods in Ireland.

Research question

• How has breastfeeding and infant feeding been defined in studies conducted in Ireland?

• What are infant and child health outcomes related to infant feeding practices in Ireland?

• What types of evidence exists regarding infant feeding practices and healthcare use in Ireland?

• What healthcare costs related to infant feeding practices have been reported in Ireland?

• What data on breastfeeding type, exposure, and duration have been reported in the Irish literature?

• What data on formula feeding type, exposure and duration have been reported in the Irish literature?

Inclusion criteria

Participants. Infants and children who are residents in Ireland.

Concept. Breastfeeding and/or feeding with breast milk using means other than the breast such as hand expression and pumped breast milk fed through cup, bottle, lactation device (Onah et al., 2025).

Formula feeding will be included. This will also include combination feeding.

Incidence or prevalence of health outcomes, health care use and costs associated with infant feeding practices (Breastfeeding, non-breastfed and combination feeding).

Context/setting. Studies undertaken in the Republic of Ireland and Northern Ireland will be included.

Types of studies. This scoping review will consider controlled, experimental or epidemiological (observational or analytic) studies.

Exclusion criteria. Studies focusing on animals, studies reporting on feeding type without reporting on health outcomes. As per Renfrew et al. (2012) and Onah et al. (2025), case reports, case series and papers not reporting a study will be excluded.

Methods

The proposed scoping review will be conducted in accordance with the JBI methodology for scoping reviews (Peters et al., 2020). This scoping review will be reported in accordance with the Preferred Reporting Items for Systematic Reviews (PRISMA) extension for scoping reviews, PRISMA-ScR (Tricco et al., 2018). This protocol is reported in line with the PRISMA-P checklist. Scoping reviews allow researchers to identify the available types of evidence and inform future research (Peters et al., 2020). This scoping review will identify and map the available research on infant and child health outcomes associated with infant feeding in Ireland to inform an Irish cost analysis.

Search strategy

The search strategy will aim to locate both published and unpublished studies. A three-step search strategy as per the JBI methodology for scoping reviews will be utilised in this review (Peters et al., 2020). First an initial limited search of PubMed and CINAHL was undertaken in July 2025 to identify articles on the topic. The text words contained in the titles and abstracts of relevant articles were used to develop a full search strategy. The current review is adapting the framework by Onah et al. (2025) to the Irish context. We adapted the search strategy (see Table 1) used in Review B (Onah et al., 2025). We intend focusing on the seven pathologies as identified by Onah et al. (2025) for the Irish cost analysis following this review, but for completeness we use the full search string (#2). The keywords contained in the search strategy for Review B by Onah et al. (2025) were used for the infant feeding and health outcome concepts, with the addition of keywords identified in the preliminary search. More specifically, commercial milk feed, baby formula, infant formula, combination feed, neonatal feed, mother milk, breast milk and maternal milk were added to the feeding concept to address the current reviews questions. Infant illness, infant health, childhood illness, child health and young child health were added to the health outcomes concept. Keywords relating to the context were changed to include Ireland and Northern Ireland (Table 1). The string related to study design was removed following an initial search, as it resulted in a narrow search with potentially relevant studies being missed. Keywords will be mapped to relevant subject headings and MeSH terms for the appropriate databases. Input was sought from a research librarian. The search strategy was reviewed by topic experts and knowledge users (JH, MM, HM, PL-W) in this area. The search strategy, including all identified keywords and index terms, will be adapted for each included database and information source. The reference list of all included sources of evidence will be screened for additional studies.

Table 1. Search Strategy.

Search	Query
#1	Title/Abstract: “Breastfeeding” OR “breast fed” OR “bottle feeding” OR “breastfeed” OR “bottle feeding” OR “bottle fed” OR “infant feeding” OR “human milk” OR “formula milk” OR “formula feed” OR “human lactation” OR “breast pump” OR “milk express” OR “weaning” OR “breast milk” OR “maternal milk” OR “mother milk” OR “commercial milk feed” OR “baby formula” OR “infant formula” OR “combination feed” OR “neonatal feed”
#2	Title/Abstract: “infant illness” OR “infant health” OR “childhood illness” OR “child health” OR “young child health” OR “Health outcomes” OR “risk factors” OR “causality” OR “mortality” OR “morbidity” OR “health status” OR “chronic disease” OR “disease susceptibility” OR “benefit” OR “protective” OR “harmful” OR “cancer” OR “neoplasms” OR “infection” OR “cholesterol” OR “cardiovascular disease” OR “diabetes” OR “blood pressure” OR “overweight” OR “obesity” OR “digestive system” OR “allergies” OR “immune system diseases” OR “osteoporosis” OR “dental caries” OR “birth intervals” OR “Sudden Infant Death” OR “vaccination” OR “asthma” OR “mental health”
#3	Title/Abstract/Author Affiliations: Ireland OR “Republic of Ireland” OR ROI OR “Health service executive” OR “Northern Ireland” OR NI OR “North of Ireland” OR “North* Ireland”
#4	1 AND 2 AND 3

(Adapted from Onah et al., 2025)

As per Onah et al. 2025, CINAHL (EBSCO) and PubMed will be searched with no restrictions. A grey literature search will be undertaken on Google scholar. As per the input from the research librarian, Lenus will also be searched for grey literature. Known experts will be contacted, including contacting authors of studies identified through database searches where appropriate. One full search has been included in this protocol (see Table 2).

Table 2. CINAHL Search undertaken on 16/09/2025.

Search	Query	No. of hits
#1	Subject Headings “Milk, Human" OR "Infant Feeding" OR "Bottle Feeding" OR "Infant Formula" OR "Breast Feeding" OR TI/AB “Breastfeed” OR “breast fed” OR “bottle feed” OR “breast feed” OR “bottle fed” OR “infant feed” OR “human milk” OR “formula milk” OR “formula feed” OR “human lactation” OR “breast pump” OR “milk express” OR “weaning” OR “breast milk” OR “maternal milk” OR “commercial milk feed” OR “baby formula” OR “infant formula” OR “combination feed” OR “neonatal feed” OR “mother milk”	50,083
#2	Subject Headings "Child Health" OR "Infant, Newborn, Diseases" OR "Infant Mortality" OR TI/AB “Health outcome” OR “child health” OR “young child* health” OR “infant illness” OR “infant health” OR “childhood illness” OR “risk factor” OR “causality” OR “mortality” OR “morbidity” OR “health status” OR “chronic disease” OR “disease susceptibility” OR “benefit” OR “protective” OR “harmful” OR “cancer” OR “neoplasms” OR “infection” OR “cholesterol” OR “cardiovascular disease” OR “diabetes” OR “blood pressure” OR “overweight” OR “obesity” OR “digestive system” OR “allerg” OR “immune system diseases” OR “osteoporosis” OR “dental caries” OR “birth intervals” OR “Sudden Infant Death” OR “vaccination” OR “asthma” OR “Mental health”	2,057,472
#3	TI/AB Ireland OR “Republic of Ireland” OR ROI OR “Health service executive” OR “Northern Ireland” OR NI	64,505
#4	1 AND 2 AND 3	167

Study/source of evidence selection

Following the search, all identified citations will be collated and uploaded into Covidence and duplicates removed. Following a pilot test, titles and abstracts will then be screened by two independent reviewers (EH & ROD) for assessment against the inclusion criteria for the review. Potentially relevant sources will be retrieved in full, and their citation details imported into Covidence. The full text of selected citations will be assessed in detail against the inclusion criteria by two independent reviewers (EH & ROD). Reasons for exclusion of sources of evidence at full text that do not meet the inclusion criteria will be recorded and reported in the scoping review. Any disagreements that arise between the reviewers at each stage of the selection process will be resolved through discussion, or with an additional reviewer (JB). The results of the search and the study inclusion process will be reported in full in the final scoping review and presented in a PRISMA flow diagram (Tricco et al., 2018).

Data extraction

Data extraction will be conducted by two independent reviewers (EH & ROD). The JBI data extraction template was modified to include the Population- Concept- Context (PCC) relevant to this review. The following data will be extracted; author, year, country, type of evidence source, study aim and objectives, methodology, participants, context, infant feeding (definition, time points examined, type, exposure and duration), infant and child health outcomes and key findings as they relate to the review questions (Table 3). The data extraction tool will be piloted by two independent reviewers and revised before use as well as during the process of data extraction, if required. Any modifications to the template will be detailed in the scoping review. If disagreements arise between reviewers during data extraction, they will be resolved through discussion or with a third reviewer (JB). If necessary, authors of papers will be contacted to request missing or additional information.

Table 3. Data Extraction Template.

Author/ Year/ Country	Type of evidence source	Aims/ Objectives	Methodology /Participants/ Context	Infant feeding (type, definition, time points examined, type, exposure and duration)	Infant and child health outcomes	Key Findings	Other (for example, healthcare costs)

Assessment of the risk of bias of included studies is not relevant as the objective of this scoping review is to describe Irish evidence on infant feeding practices and health outcomes (Peters et al., 2020).

Data analysis and presentation

The extracted data will be summarised according to the aims and objectives of this review. The data will be presented graphically in tables and figures. The included studies will be summarised based on the studies’ characteristics, including the year, study aim and objectives, participants and context.

A reflexive approach will be adopted throughout the review process. The reviewers will critically reflect on the selection of studies, interpretation of the literature and the potential biases inherent in the synthesis process.  Reflexivity will involve the reviewers’ being transparent about their perspectives, decisions made during the review process, and how these may influence findings. A reflexive statement will be included in the review discussing these considerations to provide a richer understanding of the choices made and how these may shape the conclusions drawn.

Ethics and consent

Ethics and consent were not required.

Data availability statement

File name: PRISMA-P Checklist

Available on Zenodo DOI https://doi.org/10.5281/zenodo.17946032 (Hanley, 2025) under the Creative Commons Attribution 4.0 International License (CCBY4.0 license).

Faculty Opinions recommended

References

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