External Publications Using GUI Data

Investigations into the wider bioecological understanding of dental problems in early childhood are limited in national surveys. Classification tree analysis (CTA) was used to explore multilevel interactions among key aspects of child and primary caregiver (PCG) psychosocial and physical health affecting dental problems in preschool children. Data were derived from the Growing Up in Ireland study, a nationally representative sample of 9-mo-olds (N = 11,134) in 2007/2008 followed up at age 3 y (N = 9,793) in 2010/2011. Analysis included PCG reports of children’s dental problems, general health, temperament, emotional and behavioral difficulties, and their own general health, stress and depression, relationship, and sociodemographic variables. Misclassification costs were specified for the model by applying a higher penalty for misclassifying those with a dental problem (minority class). Logistic regression analyses were carried out for comparison. Dental problems were reported among 302 infants (2.7%) at 9 mo of age and 493 children (5.0%) at 3 y. CTA identified infant temperament (Infant Characteristics Questionnaire unpredictable) as the primary predictor of dental problems at 9 mo and child global health at 3 y of age. First-level predictors were PCG depression score and use of a soother at 9 mo and PCG ethnicity and unscheduled hospital visits at 3 y of age. Regression analyses results supported the most important predictors at 9 mo and 3 y of age. The CTA model for 9-mo-old infants had a specificity of 90.4%, sensitivity of 31.2%, and overall accuracy of 88.8% while that for 3-y-olds had a specificity of 58.5%, sensitivity of 66%, and overall accuracy of 59%. Key aspects of infant/child and PCG health, as well as psychosocial characteristics associated with reported dental problems, should be considered in future multidisciplinary approaches to child health.

Knowledge Transfer Statement: The results of this data analysis should help raise awareness among clinicians of how primary caregiver and child psychosocial and general health factors are associated with early childhood dental problems, even before the primary dentition is complete. Classification tree analysis visually demonstrates how factors such as infant temperament (9 mo) and child global health (3 y) can interact at multiple levels and affect different subgroups of the child population. Future intervention strategies for oral health should involve consideration of the psychological and general health characteristics of the young child and PCG at both the patient and population levels. This knowledge could assist decision makers adopt an integrated multidisciplinary approach in formulating a coherent oral health policy for preschool children.

This retrospective cross-sectional paper examines the relationship between maternal smoking during pregnancy and children’s behavioural problems at 9 years of age independent of a wide range of possible confounders. The final sample comprised 7,505 nine-year-old school children participating in the first wave of the Growing Up in Ireland study. The children were selected through the Irish national school system using a 2-stage sampling method and were representative of the nine-year population. Information on maternal smoking during pregnancy was obtained retrospectively at 9 years of age via parental recall and children’s behavioural problems were assessed using the Strengths and Difficulties Questionnaire across separate parent and teacher-report instruments. A quasi-experimental approach using propensity score matching was used to create treatment (smoking) and control (non-smoking) groups which did not differ significantly in their propensity to smoke in terms of 16 observed characteristics. After matching on the propensity score, children whose mothers smoked during pregnancy were 3.5 % (p < 0.001) and 3.4 % (p < 0.001) more likely to score in the problematic range on the SDQ total difficulties index according to parent and teacher-report respectively. Maternal smoking during pregnancy was more strongly associated with externalising than internalising behavioural problems. Analysis of the dose–response relationship showed that the differential between matched treatment and control groups increased with level of maternal smoking. Given that smoking is a modifiable risk factor, the promotion of successful cessation in pregnancy may prevent potentially adverse long-term consequences.

Psychotic experiences (PEs) are common in early adolescence and are associated with nonpsychotic psychopathology. However, not all adolescents with PEs have subsequent psychopathology, and vice versa. To date, factors mediating the relationship between PEs and psychopathology have been understudied. The aims of this study were to investigate the bidirectional relationship between PEs and psychopathology in adolescence and to investigate potentially malleable mediators of these relationships. Data from 2 waves (age 13 and 17 years) of Cohort ’98 of the Growing Up in Ireland study were examined (n = 6,206). Using KHB pathway decomposition, we investigated the following as potential mediators of the relationship between psychopathology and PEs: parent-child relationship (conflict and positive), self-concept, and child-peer relationship (alienation and trust). Supplementary counterfactual mediation and sensitivity analyses were conducted. Early adolescents with psychopathology had twofold increased odds of late adolescent PEs (internalizing problems: odds ratio [OR] = 2.03, 95% confidence interval [CI; 1.56, 2.62]; externalizing problems: OR = 1.99, CI [1.51, 2.60]). Parent-child conflict explained between 23% and 34% of the associations between internalizing and externalizing problems and subsequent PEs. Early adolescents with PEs had increased odds of late adolescent psychopathology (internalizing problems: OR = 2.01, CI [1.61, 2.50]; externalizing problems: OR = 1.70, CI [1.25, 2.31]). Self-concept alone accounted for 52% of the relationship between PEs and subsequent internalizing problems. There is a bidirectional heterotypic relationship between psychopathology and PEs. Parent-child conflict and self-concept are important characteristics that mediate a proportion of the relationship between PEs and psychopathology. Interventions targeting parent-child conflict in the context of psychopathology and self-concept in the context of PEs may assist in reducing the incidence of poorer outcomes.

Introduction
Despite a growing body of research on associations between adolescent digital use and well-being, few studies have investigated these associations a) longitudinally and b) across socioeconomic status. The present study uses high-quality longitudinal data to examine how digital engagement shapes socioemotional and educational outcomes from early to late adolescence across socioeconomic status (SES).

Methods
Participants are 7685 individuals (49.0% female) from the 1998 birth cohort of the longitudinal Growing Up In Ireland (GUI) survey. The survey was administered to Irish parents and children between 2007 and 2016 (at ages 9, 13, and 17/18). Fixed-effects regression modeling was used to establish associations between digital engagement and socioemotional and educational outcomes. Further Fixed-Effects models were analyzed separately by SES, to assess how associations between digital use and adolescent outcomes differ by socioeconomic groups.

Results
Results show that digital screen time increases markedly from early to late adolescence, but to a higher extent among low-SES versus high-SES groups. Heavy levels of digital screen time (i.e., 3+ hours daily) are associated with declines in well-being, particularly for external and prosocial functioning, while engagement in learning-oriented digital activities and gaming is associated with better adolescent outcomes. Yet, low-SES adolescents are globally more harmed than high-SES adolescents by their digital engagement, and high-SES adolescents benefit more from moderate levels of digital use and from engaging in learning-oriented digital activities.

Conclusions
This study suggests that digital engagement is associated with socioeconomic inequalities in adolescents’ socioemotional well-being and, to a lesser extent, educational outcomes.

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.

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.

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.

There is now fairly substantial evidence of a socioeconomic gradient in low birth weight for developed countries. The standard summary statistic for this gradient is the concentration index. Using data from the recently published Growing Up in Ireland survey, this paper calculates this index for low birth weight arising from preterm and intrauterine growth retardation. It also carries out a decomposition of this index for the different sources of low birth weight and finds that income inequality appears to be less important for the case of preterm births, while father’s education and local environmental conditions appear to be more relevant for intrauterine growth retardation. The application of the standard Blinder–Oaxaca decomposition also indicates that the socioeconomic gradient for low birth weight appears to arise owing to different characteristics between rich and poor, and not because the impact of any given characteristic on low birth weight differs between rich and poor.

The quality of the interparental relationship bears important implications for children’s socioemotional development. Given evidence that relationship satisfaction among parents tends to decline over time this study examined how change in parents’ relationship satisfaction from nine-months-old until nine-years-old related to children’s socioemotional difficulties at nine-years-old. Participants were 2074 mothers, fathers, and their child (55.1% male) recruited through random sampling of the Child Benefit Registrar by Growing Up in Ireland cohort study. Mothers ranged in age from 18 to 40 years (M = 31.06, SD = 4.70) and fathers ranged in age from 18 to 60 years (M = 33.50, SD = 5.54). Mothers and fathers completed the Dyadic Adjustment Scale at nine-months-old and at nine-years-old whereas child socioemotional development was assessed via teacher report on the Strengths and Difficulties Questionnaire at nine-years-old. Residualised change analysis indicated that both parents experienced declines in relationship satisfaction from nine-months-old until nine- years-old. However, in families where initial levels of relationship satisfaction were high, there was no significant association between decline in satisfaction and child socioemotional difficulties. Conversely, in couples where initial levels of satisfaction were low, mothers, but not fathers, who experienced further declines had female, but not male, children with more socioemotional difficulties at nine years (β = −0.22, p = 0.01; R2 = 0.15, F = 2.31, p = 0.02). These findings highlight the need for carefully tailored interventions aimed at promoting couple relationship satisfaction during transition to parenthood such that the negative impact on children of any decline experienced over time can be mitigated.

Background
Whether, and how, infant characteristics and parenting quality interact is one of developmental psychology’s key questions. However, whether specific interaction patterns replicate across cohorts or developmental outcomes is largely unknown. This study investigates whether infant characteristics and parenting quality are independent predictors (additive effects) of child outcomes or interact such that certain infants particularly suffer from poor parenting (diathesis stress), particularly benefit from good parenting (vantage sensitivity) or both (differential susceptibility).

Methods
Individual participant data from over 30,000 children from four prospective cohorts were pooled. Using a competitive-confirmatory approach of model evaluation, 16 possible permutations of infant characteristics (temperament and birthweight), parenting (maternal-reported stimulating and sensitive parenting) and later developmental outcomes (fluid and crystalised intelligence, internalising and externalising behaviour) were tested. The robustness of results was evaluated by subsequently varying analytic methods, using alternative parenting measures including observer reports and excluding covariates.

Results
AIC values in 10/16 analyses indicated infant characteristics acted independently of maternal-reported parenting for predicting developmental outcomes. Interaction patterns indicating diathesis stress (4/16), vantage sensitivity (2/16) or differential susceptibility (0/16) were rare or absent. However, diathesis-stress patterns were frequently found regarding birthweight and internalising behaviours, which were largely robust to methodological changes.

Conclusions
Developmental outcomes are more consistently explained by additive effects rather than by interaction effects.

Background
Psychotic experiences (PEs) are commonly reported in adolescence and are associated with a range of negative outcomes. Few targets for intervention for PEs have been identified. One potential target is self-concept: an individual’s beliefs about his/her personal attributes. Improvements in self-concept have been shown to reduce psychotic symptoms in patients with schizophrenia but no study has investigated the relationship between changes in self-concept and risk of PEs in the general population.

We aimed to investigate: (a) the relationship between child and adolescent self-concept and adolescent PEs; and (b) whether changes in self-concept between childhood and adolescence were associated with risk of adolescent PEs.

Method
Using data from age 9 and age 13 (n = 7,423) of the child cohort (Cohort’98) from the Growing Up in Ireland study we investigated the relationship between self-concept at age 9 and age 13 and PEs at age 13. PEs were measured using the Adolescent Psychotic Symptoms Screener and self-concept was measured using the Piers Harris-II. Using a stratified analysis, we investigated the relationship between change in self-concept between age 9 and age 13 and the risk of PEs at age 13. Additionally we investigated changes across the six self-concept subscales.

Results
Psychotic experiences were reported by 13% of participants at age 13. ‘Very low’ self-concept at age 9 was associated with an increased risk of PEs at age 13 (Adjusted-OR: 2.74, CI: 1.80–4.19), and ‘High’ self-concept at age 9 was associated with a decreased risk of PEs at age 13 (Adjusted-OR: 0.77, CI: 0.60–0.97). The stratified analysis indicated that improvements in self-concept reduced the odds of adolescent PEs and decline in self-concept increased the odds of adolescent PEs. This effect was noted across the majority of the self-concept subscales.

Conclusions
There is a strong relationship between self-concept and PEs. The antecedents of low self-concept may be a useful target for preventative psychiatry. Broad-spectrum interventions targeting self-concept in childhood may help to reduce the incidence of PEs in adolescence

Children live in a technology-mediated world, and most young people use a variety of technologies in their daily lives. However, despite intense public discourse, we have little empirical evidence on how technology use impacts on children’s development across a number of psycho-social domains. Research that has been conducted tends to be largely small-scale or cross-sectional in nature and most often focused on (young) adults rather than children. Using longitudinal data on one-in-eight Irish children, we use econometric methods to test for associations between early mobile phone ownership and two measures of children’s psycho-social development between 9 and 13 years of age. We examine the Piers Harris Self-Concept Scale, reported by children, and the Strengths and Difficulties (SDQ) score, completed by the primary caregiver. We find no generalised associations between early mobile phone ownership and psycho-social outcomes. However, there is evidence that associations differ by gender and across psycho-social sub-domains. We find no robust associations affecting boys, but girls who receive phones earlier fare less well in terms of their behavioural adjustment and academic self-concept scores at 13 years of age, all else being equal. Further research is needed to identify causal mechanisms and explore possible mediating effects of family/social context.

KEYWORDS: Mobile phone ownership; psychological adjustment; self-concept; gender; longitudinal data; Piers Harris; SDQ

Objective
Childhood chronic illness can have a high impact on the child’s quality of life. The foundations of health are established in early life, and are shaped by biological, psychosocial, spiritual and environmental processes and influences. The objectives of this presentation are twofold: firstly to describe the prevalence of chronic illness in 9-year-olds in Ireland, secondly to illustrate how chronic illness influences the psychological and social development of the children.

Methods
Analysis was based on data of 8570 9-year old children, and their families who participated in Growing Up in Ireland—the National Longitudinal Study of Children. The sample was generated through the primary school system. A representative sample of 910 schools participated; the sample of children and their families was randomly selected from within the schools. Questionnaires were administered in schools; and after completion of this phase, the project interviewers visited the families of the 9-year olds in their homes and administered core questionnaires to the Study Child and his/her carers who provided either home-based or centre-based care on a regular basis.

Results
The overall prevalence of chronic illness reported by mothers among the 9-year old cohort was 11% (gender-specific prevalence for boys: 13%, and significantly lower for girls: 10%). Respiratory illnesses accounted for almost half (46%) of all chronic illnesses, followed by mental and behavioural conditions with 19% (high gender dysbalance: reported for boys in 24%, for girls in 12%). Children with a reported chronic illness had significantly more emotional, conduct, hyperactivity, peer-based and prosocial difficulties when compared with children without a reported chronic illness. Abnormal scores, based on the Strengths and Difficulties Questionnaire were found in 20% in children with a chronic disease, and in 5.5% in children without a chronic disease. Socio-economic Status was associated with poorer health outcomes. Furthermore, primary care givers’ views and perceptions regarding the chronic illness of the child were found to be a significant factor on child strengths and difficulties in a multivariate model.

Conclusions
The majority of 9-year old children can be assessed as healthy. The most common chronic illness in this large cohort was respiratory disease and overall, chronic conditions were found to have a negative impact on the child’s emotional and social state.

Background
Globally, childhood obesity is a significant public health problem associated with adverse health and economic consequences. To tackle the problem, we need a comprehensive understanding on how the environment in which we live may influence obesity related behaviours and weight status. Thus, we explore if distance to and number of food outlets ([1] supermarkets and [2] convenience stores) in the local area impact on either dietary quality or body mass index (BMI) in 9-year-old children whilst controlling for socio-economic characteristics of the family.

Methods
Cross sectional analysis of the Growing Up in Ireland (GUI) Study, a two-stage clustered sample of 8568 nine year old children from the Republic of Ireland. Children were recruited from schools (response rate 82%) and age eligible children (response rate 57%) were invited to participate. Height and weight measurements were used to calculate BMI. Diet was assessed using a short food frequency questionnaire and a dietary quality score was generated based on Irish healthy eating guidelines. Socio-economic status was measured using parent reported household class, household net equivalised income and highest level of maternal education. Food access was measured as network distance to (in quintiles) and number of (within 1000km) convenience stores and supermarkets to each participant’s household within the local area. Separate fixed effects regression models were used to assess the impact of local area food access on (1) dietary quality and (2) BMI, stratified by gender.

Results
After controlling for socio-economic characteristics of the household, distance to the nearest supermarket was not associated with dietary quality in boys (Q5 v Q1; B = 0.84, 95% CI, –0.49 to 2.18) or girls (Q5 v Q1; B = –0.41, 95% CI, –1.60 to 0.77). Distance to the nearest convenience store was associated with dietary quality in boys (Q5 v Q1; B = 1.01, 95% CI, 0.13 to 1.89) but not in girls (Q5 v Q1; B = 0.04, 95% CI, –0.71 to 0.80). The number of convenience stores or supermarkets within 1000m of the household did not impact on dietary quality. Access to food outlets was not associated with BMI in girls or boys.

Conclusion
There was little evidence to suggest that access to food stores impact dietary quality or BMI in children. From a population health perspective, strategies tackling environmental factors associated with making poor lifestyle choices are needed. Thus, further research on the association between food access and obesity risk is needed.

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.

Background
Historically, breastfeeding rates in Ireland have been low compared with international averages. It has been suggested that maternal ethnicity and citizenship may influence breastfeeding rates, with ethnic minorities thought more likely to breast feed.

Aim
The aim of this study is to investigate the association among maternal citizenship, ethnicity, birthplace and breast feeding. It is hypothesised that Irish mothers (identified through Irish citizenship, self-identified Irish ethnicity or Irish birthplace) are less likely to breast feed than non-Irish mothers.

Methods
The study population of Growing Up in Ireland: the National Longitudinal Study of Children was used for this study. Analysis was restricted to 11 092 biological mother and infant pairs with a complete breastfeeding history. Logistic regression analysis was used to estimate ORs and 95% CIs for breast feeding relative to maternal citizenship and ethnicity, controlling for the confounding effects of other maternal variables.

Results
Results indicated that 55.9% (6202 of 11 092) of mothers had initiated breast feeding, with only 7.9% (874 of 11 092) of mothers currently breast feeding their infant (at 9 months of age). Irish citizens (4693 of 9368, 50.0%) were significantly less likely to have initiated breast feeding compared with non-Irish citizens (1503 of 1695, 88.7%). Irish born mothers (4179 of 8627, 48.8%) were also significantly less likely to have initiated breast feeding than mothers born elsewhere (2023 of 2462, 82.2%).

Conclusions
Maternal citizenship and ethnicity appear to be the strongest influencing factors on breastfeeding initiation and duration. However, this raises a possibility that the increase in breastfeeding rates seen recently may be the result of increased immigration into Ireland, rather than the success of policy and research efforts.

The aim of this study was to examine the role of different types of home learning activities, such as reading, singing, painting, playing games, and letters and numbers (ABCs and 123 s), in the development of nonverbal reasoning skills in young children. Although much previous research has focused on the role of the home learning environment in the development of language and numeracy skills, few studies have explored other aspects of cognitive development such as nonverbal reasoning. The data were drawn from the Growing Up in Ireland study, a nationally representative longitudinal birth cohort study. We examined whether learning activities were associated with scores on standardized nonverbal reasoning and vocabulary tests of the British Ability Scales in a sample of 9793 3-year-old children. The regression models also controlled for other factors that potentially influence cognitive development such as the parent–child relationship and maternal education. The findings indicate that activities such as reading, games, and painting/drawing have a small but statistically significant association with nonverbal reasoning scores, as well as with vocabulary scores, even after controlling for other factors in the model. Teaching the alphabet or numbers did not make significant contributions to the model. The findings of the study highlight the importance of considering the role of different types of home learning activities, as well as other environmental factors, in different aspects of cognitive development. We consider the implications of the findings for theories of cognitive development and for supporting cognitive development in young children.

Previous research has tended to classify stepfamilies based on self-report of their familial relationships. However, some stepfamily members do not identify as being part of a stepfamily, leading to the exclusion of certain stepfamilies from stepfamily research. Using data from the first national cohort study of children in Ireland, the aim of this study was to compare the characteristics of self-identifying stepfamilies with those of non-self-identifying stepfamilies, a group about which little is known. The analysis revealed that in approximately 10% of stepfamilies, neither parent declared their stepfamily status (n = 34, N = 288 stepfamilies). No differences emerged between self-identifying and non-self-identifying stepfamilies in the quality of the parent–child or spousal relationships. Non-self-identifying stepfamilies were less likely to be complex, and were more likely to be stepmother and simple stepfamilies than self-identifying stepfamilies. These findings suggest that non-self-identifying stepfamilies constitute a significant minority of stepfamilies who may exhibit unique structural characteristics.

Keywords: stepfamily; family  relationships; identity; stepchildren; stepparents; membership status

Background
Health disparities for children with intellectual disabilities can be challenging to measure due to many other factors that can impact health and healthcare use. The aim of the current study was to use longitudinal cohort data to compare children with intellectual disability (ID) in Ireland between 2006 and 2014 on healthcare utilisation and unmet need, at ages 9 and 13, using a propensity score matching (PSM) approach.

Methods
Using data from the Growing up in Ireland study, PSM was used to identify an appropriate control sample to compare with a sample of children with ID (n = 124). Participants were matched on variables that are known to influence healthcare utilisation to reduce the impact of confounding variables between groups so that differences between the groups can be estimated. Logistic regression was used to estimate effects at ages 9 and 13.

Results
Children with ID were no more likely to have visited a general practitioner or emergency department in the past 12 months than children without ID. They did have a greater likelihood of visiting a doctor in a hospital in the past 12 months and of having an overnight stay in hospital by age 9. Primary caregivers of children with ID were more likely to report unmet health needs at ages 9 and 13.

Conclusions
This approach is a novel means of comparing healthcare use in this population by balancing the impact of other factors that may result in inequities, to which children with ID may be more vulnerable.