Health outcomes of experiencing poverty in the early years: evidence review

Chapter 2: Methods

This chapter sets out the methods used to gather evidence for this review, including indicator selection and the searching process. Additionally, it examines the strengths and limitations of the available evidence, highlighting gaps in knowledge and areas for potential further research.

Overview of methods

This evidence review is based on a process of searching for, critically appraising and synthesising Scotland-specific, and, where significant, UK-wide and international evidence that addresses the research questions.

The review was guided by the following research questions:

• What are the key indicators of health/ill health in the early years that might capture the impacts of poverty?
• What are the short/medium term outcomes of the experience of poverty in early years for children’s physical and mental health?

In this context, the review had two main objectives:

• To bring together evidence on the outcomes of experiencing poverty and living in more deprived areas for children’s physical and mental health.
• To present suggestions for action, as outlined in the literature.

The approach taken in this report is to focus on a set of key health indicators and related literature. Health indicators can provide measurable data to assess the health status of families and children and can be useful in understanding and addressing inequalities and health risks^[105]. By encompassing a range of aspects of health such as mortality rates, disease prevalence, and access to healthcare, integrating these indicators can offer a holistic view of the health of parents and children. Regular monitoring of child health and wellbeing through indicators can help ensure that children grow in environments that support nurturing care and promote health and wellbeing across the life course^[106]. These insights on indicators structured the approach of this report.

Literature searches

Search, appraisal and synthesis of the evidence took place between March 2024 and April 2025. The evidence was gathered through a preliminary rapid evidence search, two literature searches led by the Scottish Government Library Service, and a further independent search for any broader, more qualitative in nature and grey literature that may have been missed in the library searches.

A wide range of evidence sources was considered. The inclusion criteria were:

• Evidence stemming from academic papers, grey literature and other available sources in Scotland.
• Evidence published in the English language between 2018 and 2024.
• Evidence published before 2018 and/or outside the UK, provided that it had foundational importance to the research questions.

Rapid evidence search: shaping the scope

At the outset of the project, a preliminary rapid evidence search was conducted to gather insights that could be used to shape the scope of the project and inform stakeholder discussions. Concurrently, key informants working in cross-cutting areas across the Scottish Government and PHS were identified and approached for input. These informants, along with the rapid evidence search, reinforced the importance of strengthening the Scottish Government’s evidence base, provided insights and steer in relation to the review’s scope and research questions, and signposted further reading.

Scottish Government Library service: first search of the literature

The Scottish Government Library Service was first accessed in March 2024 to gain a better understanding of the literature. The literature search conducted by the library service was informed by the initial rapid search and focused on evidence published between 2014-2024 and included keywords such as ‘child poverty’, ‘deprivation’, ‘inequalities’, ‘health indicators’, ‘determinants of health’ and ‘health outcomes’ (see Annex A).

As results from the first library search were analysed and discussions with key informants progressed, new insights emerged, leading to the selection of key indicators (see Indicator selection) to frame and target the literature search on priority areas. The indicators selected shaped the focus of the second library search and subsequent independent search. This iterative approach, guided by the selected indicators, ensures that the resulting research is grounded in the data and evidence surrounding these key indicators of child health.

Scottish Government Library Service: second search of the literature

In May 2024, an updated and refined second search was carried out by the Scottish Government Library Service, concentrating on evidence published in the last six years (2018-2024). This search focused on specific aspects of the literature related to health indicators in the pre-conception and pregnancy period, using additional search terms (e.g., ‘pre-conception’ and ‘pregnancy’). Prioritising the 2018-2024 period aimed to ensure that the review incorporates the most relevant and up-to-date evidence, reflecting recent policy changes in Scotland and the wider UK and incorporating both pre- and post-pandemic insights.

Independent search

Lastly, an independent search was conducted to locate any additional evidence beyond what was gathered in the two library searches. This search expanded the review by incorporating additional longitudinal findings and official statistical publications from PHS, providing a broader and more comprehensive evidence base to inform the analysis.

Background to indicator selection

Research suggests that infant and child health and development are shaped before conception by factors related to adolescent health and the wellbeing of women before they consider pregnancy^[107]. Throughout pregnancy and after birth, a child’s health and development continue to be shaped by factors including the home environment, the experience of childbirth itself, family support and the quality of maternity and newborn care^[108]. Given this context, considering both the child’s health and development and maternal and family health and wellbeing is important^[109]. This perspective guided the approach taken in this report, with selected indicators encompassing parental health before, during, and after pregnancy, as well as infant health up to the age of three.

The World Health Organization’s Nurturing Care Framework highlights the need for a harmonised set of indicators assessing health, learning and psychosocial wellbeing in children aged 0-3 years^[110]. However, during the process of identifying relevant indicators of health/ill health in the early years, it became clear that there is no widely accepted method for selecting indicators or a universally recognised set of indicators in this context. This meant a set of indicators had to be selected specifically for this evidence review, to guide literature searching. The approach taken to choosing the indicators is set out below.

Indicator selection

The process of selecting indicators involved four key stages. First, an initial search of the literature was conducted (as described above) to familiarise with the topic area and identify consistently discussed and utilised indicators related to health and ill-health in the context of poverty in the early years. This search guided the development of a list of priority topics encompassing various aspects of parental health, and child health and development.

The priority topics were then tested with colleagues. At this stage, certain topics that were initially considered as potential ‘key’ indicators (e.g., asthma, sleep, unintentional injuries) were excluded from deeper discussion due to their less frequent and less consistent presence in the literature. Additionally, a pragmatic decision was made to exclude indicators relating to school readiness, as it went beyond the timeframe of 0-3 years.

Following this, nine key indicators were agreed for inclusion across a range of different health topics, broadly falling under the categories of parental health, child health and access to healthcare. These indicators were used to inform the refined literature searches described above. For each indicator, relevant data sources were identified, prioritising Scotland-specific evidence while incorporating supporting evidence from beyond Scotland where data gaps exist. The findings presented in this report reflect the latest available data at the time of production. The order in which indicators are presented is not intended to suggest a hierarchy of importance to child and parental health. The nine key indicators included, and their definitions are outlined below. Relevant data sources for each indicator are also listed:

1. Parental nutrition, weight and supplement use: Refers to adult dietary habits, body weight, and use of dietary supplements in the antenatal^[111], perinatal^[112] and postnatal^[113] periods.

• Births in Scotland – Public Health Scotland
• Scottish Maternal and Infant Nutrition Survey 2017 (one-off survey) – Scottish Government
• Scottish Health Survey – Scottish Government

2. Infant-feeding practices, nutrition and weight: Refers to infants' feeding methods, dietary intake, and body weight of the child in the postnatal period.

• Infant feeding statistics – Public Health Scotland
• Dietary Intake in Scotland’s Children (DISH)
• Body Mass Index of Primary 1 children in Scotland – Public Health Scotland

3. Parental tobacco, alcohol and drug use: Refers to parents' consumption of tobacco, alcohol and drugs in the antenatal, perinatal and postnatal periods.

• Scottish Health Survey – Scottish Government
• Alcohol-specific deaths – National Records of Scotland
• Drug-related deaths in Scotland – National Records of Scotland
• Antenatal booking in Scotland – Public Health Scotland
• Drug use: Health Harm – Scot PHO
• Births in Scotland - Alcohol consumption in pregnancy by Health Boards – Scottish Health and Social Care Open Data

4. Access to healthcare in the perinatal period: Refers to women's and families’ access to and use of healthcare services in the antenatal, perinatal and postnatal periods.

• Antenatal booking in Scotland – Public Health Scotland
• Births in Scotland - Neonatal Care – Scottish Health and Social Care Open Data

5. Parental mental health: Refers to parents' mental health status and levels of stress in the antenatal, perinatal and postnatal periods.

• Scottish Health Survey – Scottish Government
• MBRRACE-UK (Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries) across the UK

6. Infant mental health: Refers to the emotional and psychological well-being of infants in the postnatal period.

• Early Child Development Statistics – Public Health Scotland

7. Infant oral health: Refers to the oral health of infants in the postnatal period.

• Dental statistics: NHS Registration and Participation – Public Health Scotland

8. Infant vaccination uptake: Refers to the rate at which infants receive recommended vaccinations in the postnatal period.

• Protecting the population of Scotland from vaccine preventable diseases: Vaccination and Immunisation – Public Health Scotland

9. Infant mortality: Refers to the mortality rates of infants within the first year of life.

• Vital Events Reference Tables – National Records of Scotland

It is important to note that these indicators are interconnected and that other indicators within and beyond the health system may also be important for child health in the context of child poverty. For example, Early Child Development Statistics^[114], which show a clear gradient by deprivation^[115], are an important metric that helps detect developmental concerns early on.

Additionally, the dynamics of children’s health and the complex interaction between health and other factors cannot be fully understood with the sole use of indicators but require data from multiple sources – data from a range of sources has been used throughout this report to ensure this is taken into account. This report provides one approach and one angle on child poverty and child health and sits within a wide range of Scottish Government and other evidence in this area (see Chapter 1: Introduction and context).

Assessment of the evidence base

The evidence generated from these searches are diverse, combining recent insights (2018-2024) with foundational evidence and incorporating quantitative, qualitative, and mixed methods approaches. The reviewed sources include policy documents, official statistical publications, national guidelines, research and analytical reports, evidence syntheses, systematic and scoping reviews, critical reviews and meta-analyses, longitudinal studies, cohort studies, qualitative studies and grey literature. Together, these sources reflect a wide range of health impacts from experiences of poverty, covering both parental and child health as well as aspects of families’ interactions with the health system.

Many of the sources utilised robust methodologies, including 11 systematic reviews and 10 cohort studies, supported by numerous peer-reviewed publications. Qualitative evidence provides valuable context to complement quantitative findings; however, there is scope for further qualitative studies to enhance understanding in certain areas. For instance, research focused on infant mortality could offer more comprehensive insights into its broader impacts. Such impacts may include both short-term effects, such as immediate emotional distress and grief, and lifelong implications, such as enduring psychological trauma or changes in family planning.

Several gaps were identified in the evidence base. These include limited data on paternal influences on child health, use of supplements during pregnancy, infant mental health, oral health for children under five and disaggregated infant mortality rates by deprivation. Additionally, children's experiences and perspectives are underrepresented compared to those of parents. Furthermore, considering limited coverage in the literature, future research could also focus on the detailed aspects of implementing and evaluating initiatives, ensuring that their effectiveness and impact are thoroughly assessed. Addressing these gaps could enhance understanding and provide a more comprehensive analysis of the relationship between child poverty and health outcomes.

Limitations

This review allows for a detailed exploration of key health-related outcomes linked to the experience of poverty in the early years. By focusing on these specific areas, the review provides a clear and concise analysis of why health in the early years matters from a preventive and population health point of view.

The indicators and key health topics explored in this review provide valuable insight into child health within the context of poverty, though this approach may have certain limitations. Given the absence of a universal consensus on which indicators best capture child health and poverty-related inequalities, deliberate choices had to be made regarding their inclusion. These decisions, while carefully considered, may have certain constraints.

While this focused perspective is useful, the review also acknowledges that various social determinants intersect with the experience of poverty and influence health outcomes. Although the review attempts to briefly present these, it does not provide an exhaustive account of the complex interactions at play. Furthermore, the report focuses on area-based inequalities, but there will be other inequalities that are significant to health outcomes such as those experienced by minority ethnic communities or other protected characteristic groupings.

Additionally, the field is characterised by varying definitions of key terms (‘child poverty’ and ‘early years’) and different measurement approaches, which may not uniformly cover the same age groups or geographical areas. Despite these challenges, efforts have been made to highlight areas of agreement in the literature while acknowledging ambiguities to enhance the clarity of findings.

The next chapter will present evidence on the outcomes of experiencing poverty for children’s health based on the key health indicators that were presented in this chapter.