External Publications Using GUI Data

Purpose
Despite growing concerns about trends in cocaine use, there is a shortage of longitudinal research that prospectively examines risk and protective factors associated with cocaine initiation and use in general youth populations. This study addresses this gap.

Methods
Growing Up in Ireland is a nationally representative cohort. Individual, family, and socio-environmental exposures associated with incident past-year cocaine use at ages 17 (N = 5965) and 20 (n = 4549) were assessed with survey-weighted logistic regression using generalised estimating equations. Prevalent past-year cocaine use at 20 (N = 4679) was analysed using generalised estimating equations complemented by gradient-boosted decision trees and Shapley explanations.

Results
221 (3.7%) self-reported cocaine use at 17 and 1072 (22.9%) at 20. Alcohol use at 14 or younger was associated with eight times the odds of cocaine use at 17 (aOR 8.0, 95% CI 1.7–37.3) and 19 times at 20 (aOR 19.2, 95% CI 8.6–43.2). Peer cannabis use was associated with 7 times the odds of cocaine use at 17 (aOR 7.3, 95% CI 2.9–18.3) and double at 20 (aOR 2.4, 95% CI 1.8–3.2). Growing up in a neighbourhood where substance use was common doubled the odds of cocaine use at 17 (aOR 2.4, 95% CI 1.3–4.4). Shapley explanations revealed individual-specific positive or negative impacts of exposures.

Discussion
Cocaine use among 20-year-olds in Ireland is higher than reported internationally, and increases sharply between the ages of 17 and 20, suggesting a need for interventions targeting this age group. However, associations with early adolescent factors suggest that early interventions may also be important.

Lone mothers have been found to report lower average mental health than partnered mothers. Following the ‘stress process model’, disparities in women’s mental health by family structure could be explained by lone mothers’ higher exposure to multiple forms of stressors, compared to partnered mothers. Yet, this hypothesis has not been tested in previous studies. This study analysed four waves of longitudinal data from the Growing Up in Ireland study, spanning between the year when women gave birth (2008) to 9 years later (2017) (N = 5,654 women), to examine how family stressors (i.e., financial strain, caregiving strain, work-related strain, and parental conflict) influence mothers’ depressive symptoms by family structure. Analyses applied random-effects models and Karlson-Holm-Breen (KHB) decomposition techniques, combined with different model specifications as robustness checks (i.e., fixed-effects). Results indicate that: (1) net of sociodemographic factors, lone mothers experience higher levels of depressive symptoms than partnered mothers, with additional analyses confirming that transitioning from partnered to lone mother is associated with higher depressive symptoms, and from lone to partnered mother with reduced depressive symptoms; (2) although 41% of the observed statistical association between family structure and mothers’ depressive symptoms is direct, a larger 59% of this mental health gap is mediated by inequalities between lone and partnered mothers in their exposure to family stressors; and (3) the largest share of the observed mediation by family stressors is explained by lone mothers’ higher risks of current and past caregiving strain and parental conflict, but also by their current higher financial strain. Overall, this study suggests that lone mothers’ lower mental health, compared to partnered mothers, is largely explained by disparities in exposure to family stressors, pointing to how accumulated caregiving and parental stressors, as well as poverty risks, are key explanatory factors behind the mental well-being disadvantage that lone mothers face.

Background
There are no early, accurate, scalable methods for identifying infants at high risk of poor cognitive outcomes in childhood. We aim to develop an explainable predictive model, using machine learning and population-based cohort data, for this purpose.

Methods
Data were from 8858 participants in the Growing Up in Ireland cohort, a nationally representative study of infants and their primary caregivers (PCGs). Maternal, infant, and socioeconomic characteristics were collected at 9-months and cognitive ability measured at age 5 years. Data preprocessing, synthetic minority oversampling, and feature selection were performed prior to training a variety of machine learning models using ten-fold cross validated grid search to tune hyperparameters. Final models were tested on an unseen test set.

Results
A random forest (RF) model containing 15 participant-reported features in the first year of infant life, achieved an area under the receiver operating characteristic curve (AUROC) of 0.77 for predicting low cognitive ability at age 5. This model could detect 72% of infants with low cognitive ability, with a specificity of 66%.

Conclusions
Model performance would need to be improved before consideration as a population-level screening tool. However, this is a first step towards early, individual, risk stratification to allow targeted childhood screening.

Impact
• This study is among the first to investigate whether machine learning methods can be used at a population-level to predict which infants are at high risk of low cognitive ability in childhood.
• A random forest model using 15 features which could be easily collected in the perinatal period achieved an AUROC of 0.77 for predicting low cognitive ability.
• Improved predictive performance would be required to implement this model at a population level but this may be a first step towards early, individual, risk stratification.

Background
There are few prospective studies of factors that mediate the association between exposure to adverse childhood experiences (ACEs) and obesity in adolescence. Our aim was to address this limitation.

Methods
We used prospective data from the Growing up in Ireland cohort study, with measurements at 9, 13, and 18 years old. The exposures were 14 adverse experiences before age 9. The main outcome was body mass index (BMI) at 18 years. Mediators were daily activity, diet quality, self-image and behavioural difficulties at 13 years.

Results
Among the 4561 adolescents in the final cohort, 77.2% experienced any adversity, 50.5% were female and 26.7% were overweight/obese at 18 years. BMI Z was higher at ages 9 (0.54 vs 0.43, p < 0.05, 95% CI of difference: −0.22, −0.01) and 13 years (0.50 vs 0.35, p < 0.05, 95% CI of difference: −0.25, −0.06), in those exposed to an ACE, compared to those unexposed. Structural equation models revealed that behavioural difficulties (β = 0.01; 95% CI: 0.007–0.018, p < 0.001) and self-concept (β = 0.0027; 95% CI: 0.0004–0.0050, p = 0.026) indirectly mediate the association between exposure to ACEs and BMI at 18 years.

Conclusions
The association between ACEs and BMI in adolescence is mediated by behavioural difficulties and self-concept.

Impact

• In a previous study, we found modest associations between exposure to a range of adverse childhood experiences and weight gain at 13 years of age.
• The strength of the association between adverse childhood experiences and weight gain was lower at 18 years of age compared to the association observed at 13 years and was no longer significant after controlling for confounding and including possible mediators.
• The association between adverse childhood experiences and BMI in adolescence is indirectly mediated by behavioural difficulties and self-concept.

Background
Self-harm is a major public health concern in young people and is governed by a complex interaction of different risk factors. While many studies have identified these risk factors, less is known about how they tend to co-occur together.

Methods
A latent class analysis was conducted using risk factors for self-harm from two waves at ages 13 and 17 from the Growing Up in Ireland (GUI) study their associations with self-harm were examined longitudinally at ages 17 and 20, respectively.

Results
At age 13, there was a ‘peer problems’ group with higher probabilities of bullying, being unpopular and internalising problems and a ‘school and substance use problems’ group with higher probabilities of substance use, truancy or excessive absence from school and violence. Both of these two groups had over a two-fold risk of self-harm at age 17 in comparison to the low risk factor group. At age 17, there was a group with depression that was diagnosed by a medical professional with the highest relative risk (RR:13.9 (95 % CI 10.2–19.0)) of self-harm at age 20. Two other groups with undiagnosed depression had high probabilities of being bullied, and either high or low probabilities of substance use that had a 9.4 (95 % CI 6.8–13.1) and 7.4 (95 % CI 5.5–10.0) relative risk of self-harm at age 20, respectively.

Conclusions
Identifying hidden sub-groups using risk factors for self-harm in young people can inform potential public health interventions by clinicians and other professionals who work with young people.

This study examined the role of neighbourhood characteristics in explaining socioeconomic inequalities in child mental health (the total difficulties score from the Strengths and Difficulties Questionnaire) using data from Cohort ’08 of Growing Up in Ireland Waves 3 (age 5; baseline) and 5 (age 9; follow-up). Twenty neighbourhood items were grouped into neighbourhood safety, built environments, cohesion, interaction, and disorder. Data were analysed using regression, single and multiple mediation, and network psychometric analyses. We found that neighbourhood safety, cohesion, interaction, and disorder were associated with child mental health. These four domains separately (by up to 18 %) or in concert (by up to 23 %) partially explained socioeconomic inequalities in child mental health. Built environments may explain socioeconomic inequalities in mental health in urban children only. Findings from network analysis indicated that specific concerns over “people being drunk or taking drugs in public” and “this is a safe neighbourhood” had the strongest connections with child mental health. Improving neighbourhood characteristics may be important to reduce socioeconomic inequalities in child mental health in Ireland.

Purpose
The aim of this study is to examine the association between household energy poverty (EP) and trajectories of emotional and behavioural difficulties during childhood.

Methods
The Growing up in Ireland study is two nationally representative prospective cohorts of children. The Infant Cohort (n = 11,134) were recruited at age 9 months (9 m) and followed up at 3, 5, 7 and 9 years (y). The Child Cohort (n = 8,538) were recruited at age 9 y and followed up at 13 y and 17/18 y. EP was a composite of two relative measures of EP. Emotional and behavioural difficulties were repeatedly measured using the strengths and difficulties questionnaire (SDQ). Linear spline multilevel models were used, adjusted for confounders to examine the association between (1) EP (9 m or 3 y) and trajectories of emotional and behavioural difficulties from 3 to 9 y in the Infant Cohort and (2) EP at 9 y and the same trajectories from 9 to 18 y in the Child Cohort.

Results
In adjusted analyses, EP at 9 m or 3 y of age was associated with higher total difficulties score at 3 y (0.66, 95% CI 0.41, 0.91) and 5 y (0.77, 95% CI 0.48, 1.05) but not at 7 y or 9 y. EP at 9 y was associated with higher total difficulties score at 9 y (1.73, 95% CI 1.28, 2.18), with this difference reducing over time leading to 0.68 (95% CI 0.19, 1.17) at 17/18 y.

Conclusions
Our study demonstrates a potential association between early life EP and emotional and behavioural difficulties that may be transient and attenuate over time during childhood. Further studies are required to replicate these findings and to better understand if these associations are causal.

Background
The Covid pandemic arrived in Ireland on February 29, 2020. In the following weeks various restrictions were introduced to stem the spread of the disease. Anxiety over the spread of the disease and over the restrictions introduced had an adverse effect upon mental health. This study examines the change in mental health for two groups: young adults aged around 23 at the time of onset of Covid (the 1998 cohort) and a sample of principal carers (PCs) of children who were aged 13 at the onset of Covid (the 2008 cohort).

Methods
Data were obtained from the two cohorts of the longitudinal Growing Up In Ireland (GUI) survey. The sample included 1953 young adults (from the 1998 cohort) and 3547 principal carers (from the 2008 cohort). Mental health as measured by the Centre for Epidemiological Studies Depression—8 scale was obtained for the last pre-Covid wave and for the Covid wave (surveyed in December 2020). Observations for which CES-D8 was not available in either pre or post Covid waves were excluded. Post-Covid sampling weights were applied. The change in depression rates was decomposed into a growth and distribution effect using a Shapley decomposition. The socioeconomic gradient of CES-D8 was examined pre and post Covid using concentration indices and a transition matrix was constructed to examine the dynamics of changes in CES-D8 and depression pre and post-Covid.

Results
Relative to the last pre-Covid survey, mental health, as measured by CES-D8 deteriorated for both the young adults of the 1998 cohort and the PCs of the 2008 cohort. For young adults, the deterioration was more pronounced for females. There was no observable socioeconomic gradient for poor mental health amongst young adults, both pre and post Covid. For mothers from the 2008 cohort, a gradient was observed during the pre-COVID-19 pandemic period with poorer mental health status for lower-income and less educated mothers. This gradient was less pronounced post-Covid, the levelling-off arising from a greater deterioration in mental health for higher-income and better-educated PCs.

Conclusion
Both observed cohorts showed a significant deterioration in mental health post Covid. For young adults the effect was significantly more pronounced among females and this is consistent with generally poorer mental health amongst females in this age group. There was little or no socioeconomic gradient observed for young adults, but the gradient became more shallow for principal carers. Care must be taken in terms of drawing policy implications from this study as the Covid-19 pandemic was arguably a unique event, even allowing for the likelihood of future pandemics. However, the study highlights the vulnerability of young adults, especially females, to the mental health effects arising from major public health shocks.

This report draws on the Growing Up in Ireland (GUI) study to look at pornography use among over 4,500 young adults at 20 years of age. Pornography use was captured as part of a module of questions on different types of internet use. The rich information provided by the GUI study allows us to explore the potential influence of a range of factors on pornography use and to examine the way use is related to key aspects of wellbeing and sexual behaviour among young adults. Pornography use is found to be highly gendered, with 64 per cent of young men and 13 per cent of young women reporting use. For this reason, analyses in the report look separately at the factors for young women and men.

This paper assesses the role of shadow education (SE), i.e., organised learning activities outside formal schooling, in the lives of secondary school students of different social backgrounds and in different school settings, in a high-stakes context. It draws on multilevel analysis of longitudinal Growing Up in Ireland data, alongside narratives from in-depth case study research in 10 schools. Framed within a social reproduction approach, we show how access to SE as an educational resource is socially stratified, accessible to those with greater levels of family resources, and those attending schools with higher socio-economic student intakes. SE is viewed as an investment, particularly among students with average and above average levels of prior attainment, while high attaining students are less likely to use SE. Perhaps reflecting the normalisation of SE in the Irish context, students do not directly link engagement in such tuition to their socio-emotional wellbeing.

Care is fundamental to the fabric of social relationships and a significant proportion of the adult population is engaged in regular care for children and/or adults with illnesses or disabilities. Increasing attention internationally is being paid to the role of young carers (those under 18) and young adult carers (usually 18–25 years of age). However, much of the research conducted has been cross-sectional in nature and has focused on care for those with illnesses, rather than the full spectrum of care for others. This report draws on rich data on over 4,000 young people from Cohort ’98 of the Growing Up in Ireland (GUI) study to take a longitudinal perspective, documenting the profile of young adult carers at 17 and 20 years of age and exploring the implications of such caregiving for their wellbeing, relationships and educational pathways.

In this study, we address the following research questions:

1. What is the profile of young adult carers, in terms of gender,social background, family size and structure, migrant status, urban/rural location, and own and parental illness/disability? To whom do they provide care and how much time do they allocate to caregiving?

2. What factors predict young people’s caring at ages 17 and 20?

3. How are care responsibilities associated with young people’s wellbeing, physical health and family relationships?

4. How are care responsibilities at age 17 associated with the post-school pathway pursued at age 20 (higher education, further education and labour market entry), controlling for other factors?

Does a care role constrain postschool choices, either directly through ongoing involvement in care, or indirectly via a potential effect on academic performance?

Background:
Regulatory problems in infancy are associated with internalizing and externalizing symptom trajectories across childhood. It is unknown whether early screen media exposure exacerbates the association between infant regulatory problems and childhood internalizing and externalizing symptom trajectories.

Methods:
We studied 10,170 individuals from the Growing Up in Ireland ’08 cohort. Parents reported on their children’s regulatory problems at 9 months, screen media exposure at 3 years, and internalizing and externalizing symptoms at 3, 5, 7, and 9 years. Children were categorized based on their patterns of co-developing internalizing and externalizing symptoms using parallel process latent class growth analysis. Subsequently, multinominal logistic regression analyses were conducted to estimate whether screen media exposure (&gt;1 hour or &gt;2 hours) moderated the association between regulatory problems in infancy and co-developing internalizing and externalizing symptom classes across childhood.

Results:
There were four groups of children with distinct patterns of co-developing internalizing and externalizing symptoms: 1) low stable internalizing and low decreasing externalizing symptoms (N= 6236; 61.3%); 2) low stable internalizing and moderate stable externalizing symptoms (N= 2029; 20%); 3) moderate increasing internalizing and moderate decreasing externalizing symptoms (N= 1263; 12.4%); 4) moderate increasing internalizing and high increasing externalizing symptoms (N= 642; 6.3%). Presence of regulatory problems at 9 months and excessive screen media exposure at 3 years (particularly &gt;2 hours) were independently associated with increased likelihood of all classes. Excessive screen media exposure at 3 years did not significantly moderate the association between regulatory problems at 9 months and internalizing and externalizing symptom trajectories.

Conclusions:
Both regulatory problems in infancy and screen media exposure &gt;2 hours in early childhood are early risk factors for the development of internalizing and externalizing symptoms. However, the association between infant regulatory problems and childhood internalizing and externalizing symptoms appears to operate independently of excessive screen media exposure. Clinicians should be aware of, and treat, regulatory problems in infancy to prevent chronic patterns of self-regulatory problems across childhood. Further, they should discuss and advocate for family media plans with parents to help decrease the long-term negative effects on internalizing and externalizing symptoms.

The Irish education system is undergoing significant change as it navigates the challenges of the 2020s. Schools are at the frontline of Ireland’s efforts to integrate migrant families, build an inclusive society and tackle generational socioeconomic inequality. They are also, increasingly, key sites of contestation over deep social questions like the place of faith and secularism in public institutions and the best path to ensuring young people thrive, regardless of their gender or sexual orientation. While many of these challenges resonate across the second-level sector as all schools grapple with the difficulties and opportunities of educating young adults in today’s Ireland, the focus of this report is on the voluntary secondary school sector. The report presents rich evidence from a mixed-method research study across 21 voluntary secondary schools. The research was commissioned by the Joint Managerial Body for Voluntary Secondary Schools (JMB), with the research questions designed to examine the features and experiences of students, teachers and school leaders across the voluntary sector. However, the study allows for comparisons between experiences in voluntary secondary schools and other sectors. In particular, the survey of students undertaken in this study is compared to the nationally representative longitudinal study Growing Up in Ireland (GUI) and the International Student Assessment (PISA study) on 15 year olds in Ireland and across the European Union (EU). This approach allows for a deep exploration of the voluntary secondary sector, while also placing experiences in a national and international context.

Although children’s relationships with their parents and teachers contribute to their school adjustment and achievement, few studies have examined interactions between these relationships, particularly for father-child relationships. Using the Growing Up in Ireland birth cohort (N = 7507, 50.3% male), we examined child-adult relationship quality – rated by parents at age 3 and by teachers at age 5 – as predictors of teacher-rated behavioural adjustment and academic achievement at age 9 (indexed by self-reported academic self-concepts and performance on formal reading assessments). Controlling for prior levels of problem behaviours, verbal ability, and family SES, our results indicated that children’s relationships with parents and teachers showed small and comparable independent effects on school adjustment and achievement. For mothers and teachers, moderation analyses showed a cumulative risk pattern for conflictual relationships and a compensatory pattern for close relationships. Children are likely to benefit from improving closeness and reducing conflict in adult-child relationships as well as interventions that involve mothers, fathers, and teachers.

Specific pregnancy complications, socioeconomic position and sex have all been independently associated with child mental health outcomes, but their combined effects remain unclear. We examined whether total number of complications experienced in the pregnancy associated with mental health at 5 and 9-years, and whether this varied by sex or adverse social circumstances. Pregnancy complications were self-reported at 9-months post-natally from a list of 16 complications. Parents completed the Strengths and Difficulties Questionnaire (SDQ) when their child was 5 and 9-years. The primary outcome was the SDQ-total and scoring in the clinical range (> 16) was a secondary outcome. We applied generalized linear mixed models to a large nationally representative Irish cohort (GUI; n = 11,134). Analyses were adjusted for sex, adverse social circumstances (at 9-months), and gestational smoking. We included an interaction term between pregnancy complications and each variable respectively in separate models to examine if associations varied by sex or adverse circumstances.

After controlling for covariates, total complications associated with mental health at 5 and 9-years. Each additional pregnancy complication conferred a 10% higher total-SDQ score (exponentiated co-efficient 1.10 [95%CI 1.06–1.14], 1.20 [1.15–1.26], 1.20 [1.12–1.29] and 1.34 [1.21–1.48] for 1, 2, 3 and 4 + complications respectively). For the dichotomised outcome, generally increasing odds for clinical levels of mental health difficulties were observed (OR 1complication = 1.89, 95%CI [1.37–2.59]; OR 2complications = 2.31, 95%CI [1.53–3.50]; OR 3complications = 1.77, 95%CI [0.89–3.52]; OR 4 + complications = 6.88, 95%CI [3.29–14.40]). Females had significantly lower odds of exhibiting clinically significant mental health difficulties than males (OR = 0.43, 95%CI[0.32–0.57]).

There was no evidence that the association between pregnancy complications and child’s mental health varied by sex or social circumstances at 5 or 9-years. Males exposed to numerous pregnancy complications in the context of adverse social circumstances had the highest predicted probability of having mental health difficulties in middle childhood.

The world-wide COVID-19 pandemic significantly disrupted education, with school closures leading to a shift to remote learning. Existing and emerging research has shown that even a relatively short period of missed school has negative consequences for academic and social outcomes among children and young people, especially for those from more vulnerable families. While emerging research drawing on cross-sectional data has focussed on how the pandemic has affected immigrant youth, there is a paucity of longitudinal studies in this field. In this paper, we used the longitudinal Growing Up in Ireland study to investigate and analyse the wellbeing of migrant-origin 12-year-olds in Ireland during the COVID-19 pandemic. Our research shows that compared to their Irish peers, immigrant adolescents had poorer wellbeing, partly related to differences in family support for remote learning, in experiences of poor-quality interaction with peers and in levels of family strain.

Background
The association between multidimensional household poverty (MHP) and child and mother psychopathology trajectories is not well understood. The aim of this paper is to explore this association.

Methods
We analysed 9241 infants and mothers recruited at 9-months (m) and 32-years (y) respectively from the Growing-up-in-Ireland study and followed up when the child was aged 3, 5, 7, 9 and 13y. MHP was derived from monetary, subjective and material poverty questionnaires completed by mothers before infant age 3y using latent-class-analysis. Confounder-adjusted linear spline multilevel models were used to examine the association between MHP before 3y and trajectories of child (3-to-13y) and mother (34-to-46y) psychopathology wellbeing measures (Strengths-and-difficulties-questionnaire and Centre-for-epidemiological-studies-depression-scale, respectively).

Results
In adjusted models, MHP before 3y was associated with a higher mean difference(MD) (MD:0.67, 95%CI 0.41,0.92) in child psychopathology at 3y and this was broadly similar at age 13y (MD:0.87, 95% CI 0.57,1.17). MHP prior to 3y was associated with a higher mother psychopathology when her child was age 3y (MD:1.07, 95% CI 0.90,1.23) and this persisted albeit with a slight reduction in magnitude at age 13y of the child (MD:0.72, 95% CI 0.53,0.90).

Conclusions
Though replication in other cohorts is required, findings suggest that MHP exposure in child infancy may have early negative life course impacts on mother and child wellbeing that persist for up to a decade. If causal, these findings underscore the importance of early life course policy interventions to prevent and ameliorate poverty to reduce long term psychopathology of mothers and their children.

This article uses two longitudinal cohort studies (Growing Up in Ireland and the National Educational Panel Study) to examine how shadow education relates to academic performance in Ireland and Germany. Patterns of take-up of, and outcomes from, shadow education are found to reflect the particular country context—aimed at maintaining performance to avoid grade retention in Germany and preparing for a high-stakes upper secondary exam in Ireland. Participation enhances academic performance but only for students with lower levels of prior achievement. However, the relationship is not much stronger than with engagement in structured out-of-school activities. Thus, shadow education appears to be one of a number of strategies used by more privileged families to secure educational advantage.

Background
Research has demonstrated positive associations between adverse childhood experiences (ACEs) and substance use behaviours in young adults. However, many of these are based on cross-sectional data. The pathway between ACEs and substance misuse among emerging adults is also not fully understood and few studies have investigated potential mediating factors.

Methods
We analysed data from the Child Cohort of the Growing Up in Ireland study, a nationally representative longitudinal sample of children recruited at 9 years of age (n = 4,729). Logistic regression was used to examine individual and cumulative ACE exposure relationships with substance use at age 20 years. Mediation analyses were used to assess whether parental and peer relationships and school engagement mediate ACE history associations with substance use behaviours.

Results
ACE exposure relationships with current cannabis use, other illicit drug use and problematic drug use were observed. In particular, young adults who had experienced 2 ACEs or 3 + ACEs had an approximate two-fold (OR=1.80, 95 % CI: 1.29, 2.51) and approximate three-fold (OR=2.94, 95 % CI: 2.06, 4.19) increased odds of problematic drug use, respectively, when compared to participants who had experienced no ACEs during the study period. Mediation analyses suggested that parent and peer attachment and liking school partially mediate relationships between ACEs and substance use behaviours.

Conclusions
Children who have experienced ACEs are at higher risk of future substance use and problematic drug use. In supporting these children, identified mediators such as interpersonal relationships and school engagement may help guide selection of prevention interventions.

Background
Poverty is associated with poor outcomes, yet exposure to distinct poverty trajectories in early childhood is not well understood.

Objective
To understand the prevalence of different trajectories of household poverty and their association with mid-childhood and mother indicators of physical health and psychopathology in Ireland.

Methods
We used a nationally representative, prospective cohort (Growing Up in Ireland–Infant Cohort). Household poverty included lowest third income decile, subjective poverty and material deprivation when children were aged 9 months, and 3, 5, 9 years. We used group-based multitrajectory cluster modelling to classify trajectories of poverty. Using multivariable logistic regression, adjusted with separate child and mother confounders, we assessed the association of poverty trajectories from 9 months to 9 years with child outcomes (overweight, any longstanding illness and psychopathology) at age 9 years and the same poverty trajectories over the same 9-year period with mother outcomes (overweight, any longstanding illness and depression).

Results
Of 11 134 participants, 4 trajectories were identified: never in poverty (43.1%), material/subjective>monetary poverty (16.1%), monetary>material poverty (25.6%) and persistent poverty (15.2%). Children in persistent poverty compared with those in never in poverty experienced higher odds of being overweight at 9 years (adjusted OR (aOR) 1.70, 95% CI 1.34, 2.16), having a longstanding illness (aOR 1.51, 95% CI 1.20, 1.91), and psychopathology (aOR 2.06, 95% CI 1.42, 2.99). The outcomes for primary parents (99.7% were mothers) were as follows: having higher odds of being overweight (aOR 1.49, 95% CI 1.16, 1.92), having a longstanding illness (aOR 2.13, 95% CI 1.63, 2.79), and depression (aOR 3.54, 95% CI 2.54, 4.94).

Conclusions
Any poverty trajectory was associated with poorer psychopathology and physical well-being in late childhood for children and their mothers in Ireland.