External Publications Using GUI Data

Background
Taking oral antibiotics during childhood has been linked with an increased risk of childhood obesity. This study assessed any potential association in number of courses of antibiotics taken between 2–3 and 4–5 years of age and body mass trajectory up to age 5.

Methods
The study was a secondary analysis of 8186 children and their parents from the infant cohort of the Irish National Longitudinal Study of Children. Antibiotic use was measured by parental recall between ages 2–3 and 4–5. Longitudinal models described the relationship between antibiotic exposure and body mass index (BMI) standard deviation scores and binary outcomes, and examined interactions between covariates, which included socioeconomic status, diet assessed by food frequency questionnaires and maternal BMI.

Results
Any antibiotic usage between 2 and 3 years did not predict risk of overweight or obesity at age 5. Four or more courses of antibiotics between 2 and 3 years were independently associated with obesity at age 5 (odds ratio 1.6, 95% confidence interval 1.11–2.31). Effect size was modest (coefficient + 0.09 body mass SD units, standard error 0.04, P = 0.037). Maternal BMI modified the relationship: ≥ 4 courses of antibiotics between 2 and 3 years were associated with a + 0.12 body mass SD units increase in weight at age 5 among children of normal-weight mothers (P = 0.035), but not in children of overweight mothers.

Conclusions
Number of antibiotic courses, rather than antibiotic use, may be an important factor in any link between early antibiotic exposure and subsequent childhood obesity. Research is needed to confirm differential effects on babies of normal versus overweight/obese mothers independent of socioeconomic factors.

The paper examines the effects of socioeconomic background (SES) – measured by social class, family income and parental education – cognitive ability, and gender on a variety of key outcomes from a large longitudinal study based on a representative sample of thirteen-year-olds. The data analysed comprised 6216 children who participated in waves 1 to 3 of the Growing Up in Ireland (GUI) longitudinal survey. The outcome measures drawn from wave 3, when respondents were aged about seventeen, were: examination results and several cognitive measures, life difficulties, and quality of relationships. Three regression models were compared with and without, SES measures (occupational class, household income and parental education) and cognitive ability. On academic and cognitive attainments, cognitive ability at age 13 had substantially more explanatory power than the SES measures together. On measures of adolescent difficulties and on family relationships, cognitive ability was important, but gender and to a lesser extent, household income and parental education had some effects. Claims that class background and family income are of central importance for adolescent outcomes are not supported.

New research, conducted by the ESRI and funded by the Arts Council, shows that young people become less involved in cultural activities as they prepare for the Leaving Certificate and leave school. Using data from the Growing Up in Ireland study, the report charts a decline in reading for pleasure and taking music/drama/dance lessons between 13 and 17 years of age.

This major study, conducted by the ESRI on behalf of the Arts Council, draws on Growing Up in Ireland data to assess arts and cultural participation specifically among 3, 5, 9 and 13-year-olds

Importance Birth weight percentiles (BWPs) are often dichotomized at the 10th percentile and show statistically significant association with later cognitive performance, for both preterm and term-born children. However, research testing nonlinear associations between BWPs and cognitive performance is scarce.

Objective To investigate culturally invariant, nonlinear associations of BWPs and gestational age with later cognitive performance.

Design, Setting, and Participants In this cohort study, participants with valid neonatal and cognitive data were combined from 4 observational cohorts, including the Millennium Cohort Study, the National Longitudinal Survey of Youth 1979 Child and Young Adult cohort, Growing Up in Ireland, and the Longitudinal Study of Australian Children, with children born between 2000 and 2002, 1980 and 2010, 2007 and 2008, and 2003 and 2004, respectively. Neonatal data were parent reported before age 1 year. At approximately 5 years of age, multiple cognitive tests were performed. Follow-up at 5 years of age was the predominant focus. Data were analyzed July 17, 2023.

Exposure The parent-reported neonatal data were used to calculate BWPs according to the Fenton growth chart.

Main Outcome and Measure Scores for IQ were created from multiple measures of cognition, which were z standardized separately within each cohort.

Results Of 30 643 participants (50.8% male), 7.5% were born preterm (before 37 weeks gestation) and 92.5% were term born (between 37 and 42 weeks gestation). In the pooled data using multivariate adaptive regression splines, IQ linearly increased by 4.2 points as BWPs increased from the first to the 69th percentile before completely plateauing. For gestational age, IQ linearly increased by 1.3 points per week up until 32 weeks, with the association reducing to 0.3 points per week after 32 weeks. The association of BWP with IQ was not moderated by gestational age. For term-born infants, the estimated IQ score was only clinically meaningfully lower than average when birth weight was below the third percentile. Consistent results were found when instead using multivariable regression where gestational age and BWPs were categorized into groups.

Conclusions and Relevance In this cohort study, lower BWPs and gestational age were independently associated with lower IQ. For term-born infants, a cutoff of the third percentile would be more appropriate than the traditionally used 10th percentile when the aim is estimating meaningful cognitive differences.

Background
Public health policies attempt to increase parental identification of child overweight and obesity. The objective of the present research was to determine the cross-sectional, prospective and longitudinal associations between parental identification of child overweight and child mental health problems.

Methods
We made use of two cohort studies of Australian (Longitudinal Study of Australian Children, LSAC) and Irish children (Growing up in Ireland Study, GUI) that measured parental identification of child overweight and child mental health problems. Participant included 6502 (LSAC) and 7503 (GUI) children (49% female) and their parents. Child mental health problems were measured using child, parent and teacher-reported Strengths and Difficulties Questionnaires (SDQ) at ages 9/10 years old to 12/13 years old. In all analyses we controlled for child Z-BMI.

Results
In LSAC children whose parents identified them as being overweight at age 10 experienced worse mental health at age 10 (β = 0.21, SE = 0.04) and age 12 (β = 0.13, SE = 0.04) than children whose parents failed to identify them as overweight. In GUI children whose parents identified them as being overweight at age 9 experienced worse mental health at age 9 (β = 0.20, SE = 0.04) and age 13 (β = 0.22, SE = 0.04). In LSAC parental identification of child overweight at age 10 did not significantly predict changes in mental health problems from age 10 to 12 (β = −0.02, SE = 0.03). In GUI parental identification of child overweight was predictive of increases in mental health problems from age 9 to 13 (β = 0.08, SE = 0.03).

Conclusions
Parental identification of child overweight and obesity is associated with worse child mental health, independent of child body weight. Parents should be aware of the potential stigma and mental health difficulties associated with labelling a child as overweight.

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.

While the role parents play in supporting young people is well established, support from other caring adults also becomes important during adolescence, particularly when young people are facing problems in their lives. The goal of this paper is to reflect on youth support seeking when facing problems, exploring differences between youth who seek support from parents only and those who seek support from parents and other non-parental adults. This paper outlines the findings of a secondary analysis of data from the third wave of the Growing up in Ireland child cohort at 17/18 years, collected from primary caregivers and youth. From 6126 young people in the national sample, 91.3% answered the selective question about the type of adult support they seek. Of this cohort, 36% of young people seek support from a parent and 48% go to a parent and another adult. Comparing these groups, there are significant differences found in both their individual and contextual characteristics, with better outcomes for youth with additional non-parental adult support, including using active coping strategies, better self-esteem, and identity resolution. While the findings indicate that non-parental adults have a positive influence in different areas of youth well-being, further research is required to better understand the ways in which support from non-parental adults helps young people in their transition to adulthood.

Keywords
Supportive adults, natural mentors, youth, transition to adulthood, parenting

Background
Children with a parent who smokes are more likely to become substance users than those who do not have a parent who smokes. In this study, we examined whether childhood or early adolescent exposure to primary parent smoking increased the risk of subsequent teenage alcohol and drug use at ages 17–18 years.

Methods
For this longitudinal observational study, we analysed data from 6039 teenagers and their parents from the waves 1–3 of the Growing up in Ireland Cohort 98’ Study. Parental smoking was assessed at baseline (9 years) and wave 2 (13 years) with responses coded as yes or no. The primary parent was defined as the person who provided most care and who knew most about the Study Child, usually the mother or mother figure for 98% of study participants. Teenage alcohol and drug use assessed at ages 17–18 years (wave 3) was determined by responses to the question “Have you ever consumed alcohol?” (answers yes or no), drug use was assessed by questions on ever trying aerosols/gas, cannabis, and non-prescribed drugs, with those answering yes being classified as other-drug ever users. We did a logistic regression analysis to examine the associations between parents’ smoking on teenage alcohol and drug use, controlling for covariates: gender, education, income, education, region, and household type. Ethics approval for the GUI project was obtained from the Health Research Board.

Findings
Of the 6039 teenagers included in our study, 2968 (49%) were female, 3070 (51%) were male, 5351 (89%) ever used alcohol, 5065 (85%) were current users, and 2098 (35%) used other drugs. Rates of primary parent smoking were 31% (n=1883) in wave 1 and 30% (n=1829) in wave 2. After adjusting for other exposures known to be associated with teenage substance use, primary parent smoking at waves 1 and 2 was associated with higher odds of teenage alcohol ever use (adjusted odds ratios [aORs] 1·89 [95% CI 1·44–-2·46] at wave 1 and 1·53 [1·20–1·98] at wave 2), current alcohol use (1·88 [1·50–2·36] and 1·59 [1·28–1·97]) and other-drug ever use (1·699 [1·45–1·95] and 1·71 [1·47–1·98]).

Interpretation
Teenagers aged 17–18 years exposed at ages 9 and 13 years to parental smoking were more likely to report significantly higher odds of alcohol and drug use at age 17–18 years. The finding that exposure to parent smoking in childhood increases the risk of teenage alcohol and other drug use suggests a need for interventions aimed at parents who smoke Limitations include potential unmeasured or residual confounders and reliance on self-reported teenage substance use behaviours.

Funding
Royal City of Dublin Hospital Trust, Irish Research Council Government of Ireland Postgraduate Scholarship Programme.

The purpose of this study is to investigate the influence of background and school factors on second-level students’ attitudes toward Irish as a school subject drawing on the Growing Up in Ireland study. The study focuses on the perceptions of the core subjects, English, Mathematics and Irish, and presents a profile of students who find the Irish language interesting or difficult. The study enables us to investigate the attitudes of teenagers towards the language in a systematic way, including personal, school and other characteristics that may have an impact on attitudes towards the Irish language.

This report explores factors influencing attitudes to, and the use of, the Irish language on the island of Ireland. In so doing, the report draws, first and foremost, on 2013 Irish Language Survey. In order to explore changes in attitudes over time, the study also draws on earlier (2001) survey data. Further insights into overall trends will be provided by the analysis of Census data. Given that attitudes are often shaped by schooling, the study also draws on the Growing Up in Ireland study (9-year-cohort) as well as the Irish Post Primary Longitudinal Study (PPLS) which indicate student perspectives on Irish.

Background
While it has been purported that excessive screen time can lead to behavioral problems, it has also been suggested that children with behavioral dysregulation receive more access to screens to manage problematic behavior. In this study, both temporally stable and longitudinal associations between screen time and externalizing and internalizing behaviors across childhood are examined to directly address this issue of directionality.

Methods
Data are from a prospective cohort of 10,172 Irish children, collected between 2010 and 2018 when children were ages 3, 5, 7, and 9. Children’s screen time (hours/day) and externalizing and internalizing behaviors (Strengths and Difficulties Questionnaire) were assessed via caregiver report. Random-intercepts cross-lagged panel models were used to estimate longitudinal bidirectional associations while controlling for temporally stable (i.e., ‘time-invariant’ or ‘trait-like’) differences between children.

Results
Temporally stable differences between children were observed for both screen time and behavior problems. Longitudinal trajectories for screen time lacked stability; however, and externalizing and internalizing behaviors stabilized increasingly during later childhood. Greater externalizing and internalizing behaviors at age 3 were directionally associated with increased screen time at age 5. Greater screen time at ages 3 and 5 was directionally associated with increased internalizing behaviors at ages 5 and 7, respectively. More screen time at age 7 was directionally associated with fewer internalizing behaviors at age 9. Screen time was not associated with later externalizing behaviors.

Conclusions
Bidirectional associations between screen time and internalizing behaviors were observed for preschoolers. Directional associations between screen time and internalizing difficulties were observed across childhood. These findings can inform screen use guidelines and family media planning at different ages and stages of development.

The Growing Up in Ireland Infant Cohort dataset (n = 11,134) includes information on fertility treatments for over 400 infants. IVF (28.1 %) and IVF-related treatments (17.8 %) were the most frequent, but there was also a high percentage following clomiphene citrate alone (31.5 %). Infants born following fertility treatment were much more likely to be in higher income families, and this relationship was not accounted for by older mothers in wealthier families. Analysis of fertility-treatment pregnancies among Irish infants, controlling for income and maternal age, shows a greater risk of multiple birth and low birth-weight, although the latter appears to be largely related to the former especially for IVF-type treatments.

This paper examines mobility and changes in Body Mass Index (BMI) for a sample of Irish children/adolescents across three waves of the longitudinal Growing Up in Ireland dataset. Particular attention is paid to transitions across the key BMI thresholds of overweight and obesity. Analysis is carried out by gender and by maternal education. In general, mobility is observed, with intra-generational rank-rank BMI coefficients of around 0.63 compared to coefficients of around 0.77 for the mothers of the children over the same time period. Across the distribution as a whole there is relatively little variation by gender and maternal education. However there a gender difference in terms of mobility out of obesity with the Shorrocks mobility index across categories of normal weight/overweight/obesity taking a value of 0.56 for females as opposed to 0.71 for males. This relative lack of mobility is more observed in later rather than earlier adolescence.

Objective
To longitudinally investigate body mass index (BMI) in young children in Ireland and identify factors and critical time points associated with changes in BMI.

Study design
Data on 11 134 children were collected in the nationally representative Growing Up in Ireland infant cohort study. Height and weight were measured at 9 months, 3 years, and 5 years of age. Multilevel regression was used to identify risk factors associated with changes in BMI over time (n = 10 377), combining a unique set of covariates collected from the child and the 2 main caregivers (usually the mother and father).

Results
The proportion of children ≥85th percentile of World Health Organization growth criteria was 39% at 9 months, 44% at 3 years, and 30% at 5 years. Children born large for gestational age (13%) and those with rapid infant weight gain (25%) consistently had higher BMI. Low average BMIs were consistently seen in children born small for gestational age (10%) or before 37 weeks (7%). Smaller variations in BMI existed for other factors including ethnicity, household structure, caregiver weight status, breastfeeding, sex, socioeconomic status, sleeping hours, childcare, and region.

Conclusions
In this study, differences at birth and in infancy appear to be most strongly associated with variation in BMI at all ages. Nevertheless, belonging to a number of other high-risk groups cumulatively could lead children to develop critical weight states. Policy-makers should target families with interventions before and during pregnancy when dominant risk factors are still modifiable. Longer-term follow-up of children may be needed to study associations later in childhood.

Keywords
Growing Up in Ireland, body mass index, childhood obesity, growth trajectories, multilevel modelling

Whether breastfeeding is protective against the development of childhood overweight and obesity remains the subject of considerable debate. Although a number of meta-analyses and syntheses of the literature have concluded that the greater preponderance of evidence indicates that breastfeeding reduces the risk of obesity, these findings are by no means conclusive. The present study used data from the Growing Up in Ireland study to examine the relationship between retrospectively recalled breastfeeding data and contemporaneously measured weight status for 7798 children at nine-years of age controlling for a wide range of variables including; socio-demographic factors, the child’s own lifestyle-related behaviours, and parental BMI. The results of the multivariable analysis indicated that being breastfed for between 13 and 25 weeks was associated with a 38 percent (p < 0.05) reduction in the risk of obesity at nine-years of age, while being breastfed for 26 weeks or more was associated with a 51 percent (p < 0.01) reduction in the risk of obesity at nine-years of age. Moreover, results pointed towards a dose–response patterning in the data for those breastfed in excess of 4 weeks. Possible mechanisms conveying this health benefit include slower patterns of growth among breastfed children, which it is believed, are largely attributable to differences in the composition of human breast milk compared with synthesised formula. The suggestion that the choice of infant feeding method has important implications for health and development is tantalising as it identifies a modifiable health behaviour that is amenable to intervention in primary health care settings and has the potential to improve the health of the population.

This study examined whether being breastfed predicts handedness. Two large representative samples from Britain (n=13,421) and Ireland (n=8,426) were used. Multivariate probit models are estimated, reporting the marginal effects of covariates on the probability of a child being right-handed. For both datasets, children who have been breastfed for a minimum period (between 1 month and 6 weeks) are significantly less likely to be left-handed. The results are robust to a variety of controls. Hence breastfeeding is an environmental factor that predicts handedness in a non-linear way, although the mechanism is unknown.

Keywords: Breastfeeding; Lactation;b Handedness; Laterality

BACKGROUND AND OBJECTIVES
There is mixed evidence from correlational studies that breastfeeding impacts children’s development. Propensity score matching with large samples can be an effective tool to remove potential bias from observed confounders in correlational studies. The aim of this study was to investigate the impact of breastfeeding on children’s cognitive and noncognitive development at 3 and 5 years of age.

METHODS
Participants included ∼8000 families from the Growing Up in Ireland longitudinal infant cohort, who were identified from the Child Benefit Register and randomly selected to participate. Parent and teacher reports and standardized assessments were used to collect information on children’s problem behaviors, expressive vocabulary, and cognitive abilities at age 3 and 5 years. Breastfeeding information was collected via maternal report. Propensity score matching was used to compare the average treatment effects on those who were breastfed.

RESULTS
Before matching, breastfeeding was associated with better development on almost every outcome. After matching and adjustment for multiple testing, only 1 of the 13 outcomes remained statistically significant: children’s hyperactivity (difference score, –0.84; 95% confidence interval, –1.33 to –0.35) at age 3 years for children who were breastfed for at least 6 months. No statistically significant differences were observed postmatching on any outcome at age 5 years.

CONCLUSIONS
Although 1 positive benefit of breastfeeding was found by using propensity score matching, the effect size was modest in practical terms. No support was found for statistically significant gains at age 5 years, suggesting that the earlier observed benefit from breastfeeding may not be maintained once children enter school.

This study investigates the long-term effects of victimization from middle adolescence to late adolescence and early adulthood, examining emotional and behavioral problems, peer relationships, and smoking habits and sleeping difficulties. The study also explores how these outcomes can persist into early adulthood, taking into consideration early victimization experiences, gender, cognitive ability, and family social class. The total sample included 7525 participants, spanning the ages of 13, 17, and 20, from the Child Cohort of the Growing Up in Ireland study (48.9% male). The path analysis model suggests that victimization is associated with behavioral problems at age 17, and it is also linked to emotional problems and sleeping difficulties at both ages 17 and 20. Additionally, sleeping difficulties, smoking habits, and indices of emotional and behavioral adjustment exhibit some stability between ages 13 and 17, as well as 17 and 20. Theoretical and practical implications are discussed.