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Human milk and preventive neonatology: a reflection of breastfeeding in Ireland, and an analysis of human milk bioactivity and health benefits, with special reference to prematurity
Date
2025
Abstract
Breast milk offers multi-morbidity protection to infants, and mother’s own milk (MOM) is the normative nutritional choice. Affecting nearly 10% of live births globally, prematurity poses major clinical and public health conundrum with immediate and long-term morbidities, and is a significant contributor to under-five mortality. When MOM is insufficient or unavailable for the very premature infants, donor human milk (DHM) is considered next best enteral nutritional surrogate to MOM in comparison to bovine-origin commercial milk formula (CMF). Multi-nutrient fortification of human milk (HM) is recommended to optimise the nutritional content and promote tissue accretion of very low birthweight (VLBW) infants. Ireland, having one of the lowest breastfeeding rates globally, poses additional challenges in optimising HM intake among premature infants.
This thesis addresses the critical value of HM in infant nutrition, and highlights the concept of ‘preventive neonatology’ through a cluster of interrelated epidemiological, observational and experimental studies, and systematic reviews.
This thesis aims to highlight the varied health benefits offered to infants by HM, with special reference to its bioactivity-linked roles. A mixed method approach was adopted and the following specific objectives were selected, 1. An evaluation of barriers and challenges contributing to the low Irish breastfeeding rates focussing on the Mid-West region, 2. Analysis of two decades data submitted to the Vermont Oxford Network (VON) international neonatal benchmarking registry from University Maternity Hospital Limerick (UMHL) to demonstrate the value of a quality improvement (QI) initiative and action research (AR) methodology in optimising HM intake and quantify the associated reduction in necrotising enterocolitis (NEC) among a VLBW cohort, 3. Laboratory analysis of bioactivity offered by HM and an exclusive human milk diet (EHMD), potentially contributing to NEC prevention, 4. A systematic review of early vs late HM uptake on the incidence of late-onset sepsis (LOS) and duration of parenteral nutrition (PN) among VLBW infants, 5. An evidence synthesis of the influence of breastfeeding in reducing the incidence and severity of common viral infections in infancy, such as respiratory syncytial virus (RSV), through a systematic review, and 6. An exploration of how the ‘COVID-19 lockdown’ galvanised a unique ‘nature’s experiment’ to reduce preterm births in Ireland.
The following results summarise the observations from our six interlinked studies,
1. A repeated cross‐sectional analysis of breastfeeding initiation rates for two decades from the Mid-West region, housing areas of economic deprivation, has demonstrated an overall improvement, however still significantly low, on international parity. We have determined ‘10 plausible reasons’, and proposed ‘10 Priorities’ to increase breastfeeding rates in Ireland.
2. A birth cohort data over two decades on VLBW and extremely low birthweight (ELBW) infants submitted to the VON international benchmarking registry has shown a sustained improvement in HM exposure, particularly among ELBW infants from 2012 to 2020, having a 100% exposure to HM (either MOM or DHM), and a concurrent reduction of NEC.
3. From our laboratory analysis of bioactivity of HM, a significantly lower concentration of lactoferrin and α-lactalbumin was exhibited by DHM compared to fresh and frozen MOM. Freshly expressed MOM and human milk-derived fortifier (HMDF) had the highest antioxidant activity (AA) among the tested samples, suggesting the potential capability of HMDF to enhance oxidative scavenging over cow’s milk-derived fortifier (CMDF).
4. The value of an early HM intake on the duration of PN and incidence of LOS in VLBW infants was also analysed through a systematic review. Among an intrauterine growth–restricted (IUGR) cohort, early HM resulted in statistically significant reduction in PN dependence. Two observational studies found similar reductions in PN usage and LOS among the early HM exposed cohort.
5. A systematic review of impact of breastfeeding on the incidence and severity of respiratory syncytial virus (RSV) - associated acute lower respiratory infections (ALRI) in infants indicated that an exclusive breastfeeding for >4–6 months significantly lowered hospitalisation, length of stay, supplemental oxygen and admission to intensive care units.
6. Finally, COVID-19 lockdown and public health mitigation measures in Ireland offered an unparalleled opportunity to analyse the influence of socioenvironmental modifications on prematurity. An unprecedented reduction in births of VLBW and ELBW infants was observed as a ‘natural experiment’. Poisson regression analysis found a 73% reduction in VLBW births from January to April 2020, compared to corresponding period of preceding decades.
This thesis contributes to the growing evidence of the critical value of HM in infant nutrition and attempts to fill some of the evidence gaps existing. The first five chapters individually and collectively enhance our understanding of the uniqueness of HM-based enteral nutrition with special reference to premature infants, and the last chapter highlights the socioenvironmental influencers of premature births in the context of COVID-19 lockdown.
Aetiology of prematurity is multifactorial, however our observations suggests modifiable socioenvironmental factors. Optimal nutritional critical care with a human milk-based 3E approach: ‘early, enterally and exclusively’ offers unique bioactive and immunological components, and facilitates intestinal eubiosis among VLBW infants. Implementation of the recommended multiagency approach could improve Irish breastfeeding rates and reduce infant morbidities, including RSV-associated ALRI. Optimising an exclusive MOM uptake as an integral component of ‘preventive neonatology’ would be an ideal health care investment and primary prevention with potential for long-term dividends in societal health.
Supervisor
Dunne, Colum P.
McGrath, Deirdre
McGrath, Deirdre
Description
Publisher
University of Limerick
Citation
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Files
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Philip_2025_Human.pdf
Adobe PDF, 12.9 MB
Funding code
Funding Information
Sustainable Development Goals
Type
Thesis
Rights
http://creativecommons.org/licenses/by-nc-sa/4.0/