External Publications Using GUI Data

Whether school composition makes a difference for student outcomes has been the subject of much controversy. This article draws on Growing Up in Ireland data, a rich source of information on nine-year-old children along with the characteristics of their school and classroom teacher. In contrast to many studies which rely on a single measure of social background, the use of a range of measures (including social class, parental education and income) allows us to provide precise estimates of differences in performance between schools designated as disadvantaged and other schools. The analyses also provide new insights into the processes underlying such differences. Only the most disadvantaged schools, those in Urban Band 1, are found to have a contextual effect for both reading and mathematics. This achievement gap is found to reflect differences in teacher experience and turnover, the concentration of additional learning needs, absenteeism levels and children’s engagement in school.

Keywords
school social mix, primary education, academic performance

The transition from primary to secondary school represents one of the key junctions in the educational career of young people. Research has shown that much of the challenge in this transition stems from changing social structures and encountering different learning environments. However, the transition experiences of students with special educational needs (SEN) have received relatively little attention. Drawing on large-scale longitudinal data from over 7000 young people, we examine the extent to which students with different SEN experience additional transition barriers to their peers. The findings show that young people with SEN are more likely to experience a negative transition to secondary school. Furthermore, the type of need matters and students with general learning disabilities and intellectual disabilities are three times more likely to experience poor transition compared to young people without SEN. Transition experiences also vary by gender and socio-economic status, with girls and lower socio-economic groups more at risk. This paper highlights the importance of supporting students through to their second year in secondary education, promoting positive teacher–student interactions and providing additional supports for those with lower achievement in primary school. For students with disabilities, the research highlights a need for more effective transition supports, particularly during the pre-transition period.

Keywords
Transition, academic supports, social supports, special educational needs, secondary school

The present study examines whether breastfeeding is associated with neuro-developmental advantages at 9 months of age on a standardised measure of infant development in a large cohort study of Irish children. It is hypothesised that if breast-milk confers an independent benefit, infants who were never breastfed will have reached fewer developmental milestones than those who were partially or exclusively breastfed, after controlling for putative confounding variables. Families with infants aged 9-months were recruited as part of a nationally representative sample for the birth cohort of the Growing Up in Ireland study (n = 11,134). Information was collected from mothers on breastfeeding practices, socio-demographic characteristics and developmental progress during a household interview. Parent-report items on development covered communication, gross motor, fine motor, problem solving and personal-social skills. Analysis of pass/fail status in each developmental domain using binary logistic regression showed a positive effect of any breastfeeding on gross motor, fine motor, problem solving and personal-social skills (but not communication) and these remained after adjustment for a range of confounding variables. There was, however, little evidence of a dose–response effect or advantage of exclusive over partial breastfeeding. A clear advantage of breastfeeding on infant development was demonstrated. However, the lack of a dose–response association on pass rates suggests that the breastfeeding effect may be confounded by other unobserved factors or that there is a critical threshold during which time the effect of breast milk may be particularly salient for bolstering brain development.

This retrospective cross-sectional paper examines the relationship between early breastfeeding exposure and children’s academic test scores at nine years of age independent of a wide range of possible confounders. The final sample comprised 8226 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 relating to breastfeeding initiation and exposure duration was obtained retrospectively at nine years of age via parental recall and children’s academic performance was assessed using standardised reading and mathematics tests. Hierarchical linear regression analysis with robust standard errors to control for clustering at the school level was used to quantify the effect of breastfeeding on children’s test scores. Propensity score matching was used to compare treatment effects across groups defined by their propensity to breastfeed. In unadjusted analysis, children who were breastfed scored 8.67 percentage points higher on reading and 7.42 percentage points higher on mathematics compared to those who were never breastfed. While the breastfeeding advantage attenuated appreciably when adjusted for a range of child, maternal, socio-economic and socio-environmental characteristics, children who were breastfed continued to enjoy a significant test score advantage of 3.24 (p < 0.001) and 2.23 (p < 0.001) percentage points on reading and mathematics respectively compared to those who were never breastfed. Any amount of breastfeeding was associated with significantly higher test scores than no exposure, but evidence of a dose-response relationship was weak. The results of the propensity score matching analysis indicated that the test score advantage of breastfed children is robust and that the magnitude of the effect varies across groups defined by their propensity to breastfeed, being largest amongst the most socially disadvantaged and falling to near zero among the most advantaged group.

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 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.

Background
Social inequalities in the prevalence of childhood overweight and obesity are well-established, but less is known about when the social gradient first emerges and how it evolves across childhood and adolescence.

Objective
This study examines maternal education differentials in children’s body mass trajectories in infancy, childhood and adolescence using data from four contemporary European child cohorts.

Methods
Prospective data on children’s body mass index (BMI) were obtained from four cohort studies—Generation XXI (G21—Portugal), Growing Up in Ireland (GUI) infant and child cohorts, and the Millennium Cohort Study (MCS—UK)—involving a total sample of 41,399 children and 120,140 observations. Children’s BMI trajectories were modelled by maternal education level using mixed-effect models.

Results
Maternal educational inequalities in children’s BMI were evident as early as three years of age. Children from lower maternal educational backgrounds were characterised by accelerated BMI growth, and the extent of the disparity was such that boys from primary-educated backgrounds measured 0.42 kg/m2 (95% CI 0.24, 0.60) heavier at 7 years of age in G21, 0.90 kg/m2(95% CI 0.60, 1.19) heavier at 13 years of age in GUI and 0.75 kg/m2 (95% CI 0.52, 0.97) heavier in MCS at 14 years of age. The corresponding figures for girls were 0.71 kg/m2 (95% CI 0.50, 0.91), 1.31 kg/m2 (95% CI 1.00, 1.62) and 0.76 kg/m2 (95% CI 0.53, 1.00) in G21, GUI and MCS, respectively.

Conclusions
Maternal education is a strong predictor of BMI across European nations. Socio-economic differentials emerge early and widen across childhood, highlighting the need for early intervention.

Background
Unintended pregnancy is associated with increased risk for adverse neonatal and early childhood outcomes spanning an array of indicators, but it remains unclear whether these risks hold independent of other biological, social and environmental risk factors.

Methods
This study uses data from the first wave of the ‘Growing Up in Ireland Study’, a large nationally representative cohort study of more than 11 000 infants, to examine the risk factors associated with unintended pregnancy. Adopting a staged approach to the analysis, the study investigates whether pregnancy intention influences maternal health behaviours during pregnancy independent of background characteristics, and whether pregnancy intention carries any additional risk for adverse infant and maternal health outcomes when we adjust for background characteristics and prenatal behaviours.

Results
The study confirmed that sociodemographic factors are strongly associated with unintended pregnancy and that unintended pregnancy is associated with a range of health compromising behaviours that are known to be harmful to the developing fetus. While there was little evidence to suggest that pregnancy intention was associated with adverse neonatal outcomes or developmental delay independent of other covariates, there was strong evidence that intention status had a bearing on the mother’s psychosocial health. Unintended pregnancy was associated with increased risk of depression (risk ratio 1.36 [95% confidence interval 1.19, 1.54]), and higher parenting stress (risk ratio 1.27 [95% confidence interval 1.16, 1.38]).

Conclusions
Ascertaining the mother’s pregnancy intention during the first antenatal visit may represent a means for monitoring those at greatest risk for adverse mother and child outcomes.

Background
Height is regarded as a marker of early-life illness, adversity, nutrition and psychosocial stress, but the extent to which differences in height are determined by early-life socioeconomic circumstances, particularly in contemporary populations, is unclear. This study examined socioeconomic differences in children’s height trajectories from birth through to 21 years of age in four European countries.

Methods
Data were from six prospective cohort studies—Generation XXI, Growing Up in Ireland (infant and child cohorts), Millennium Cohort Study, EPITeen and Cardiovascular Risk in Young Finns Study—comprising a total of 49 492 children with growth measured repeatedly from 1980 to 2014. We modelled differences in children’s growth trajectories over time by maternal educational level using hierarchical models with fixed and random components for each cohort study.

Results
Across most cohorts at practically all ages, children from lower educated mothers were shorter on average. The gradient in height was consistently observed at 3 years of age with the difference in expected height between maternal education groups ranging between −0.55 and −1.53 cm for boys and −0.42 to −1.50 cm for girls across the different studies and widening across childhood. The height deficit persists into adolescence and early adulthood. By age 21, boys from primary educated maternal backgrounds lag the tertiary educated by −0.67 cm (Portugal) and −2.15 cm (Finland). The comparable figures for girls were −2.49 cm (Portugal) and −2.93 cm (Finland).

Conclusions
Significant differences in children’s height by maternal education persist in modern child populations in Europe.

This paper examines the relationship between maternal employment, childcare during infancy and the overweight status of pre-school children. Using data from the Infant Cohort of the Growing-Up in Ireland Survey, propensity score matching addresses the issue of potential selection bias, quantile regression allows the impact of both maternal employment and childcare to be examined throughout the weight distribution and multiple imputation is used to address the problem of missing data due to item non-response. The results suggest that both full-time and part-time maternal employment when a child is 9 months old increase the likelihood of being overweight at 3 years old, but only for children of mothers with higher levels of education. Informal childcare at 9 months also has harmful effects on child weight, but again only for children of more educated mothers. Quantile regression finds that the children most impacted by maternal employment are those at the upper percentiles of the weight distribution. When selection on observables is used to assess bias arising from selection on unobservables, maternal employment estimates are determined to be a lower bound, while informal childcare results could be attributed to selection bias. Overall findings are consistent with research from North America and the United Kingdom, and are in contrast to recent findings from the rest of Europe, suggesting the possible role of institutional factors.

Objective
This paper examines the joint impact of maternal employment and childcare during infancy on childhood weight at ages three and five in the context of weak social support for early childhood care and education.

Method
Using three waves of longitudinal data from the Growing-Up in Ireland survey (n = 8,393 age three, n = 8,039 age five), propensity score matching is used to address the endogeneity of employment and childcare decisions. Selection on observables is used to assess potential bias arising from selection on unobservables whereby unobserved characteristics of the mother or child may jointly influence child weight and maternal employment and childcare.

Results
Full-time maternal employment at nine months combined with either formal or informal childcare increases the likelihood of being overweight at three years by 8.1% and 5.9% respectively, but only for children of highly educated mothers. Similar results are observed for part-time employment coupled with informal (7.5%) or parental (8.0%) care. The results for mothers with lower levels of education are either not significant or favourable. While the majority of the effects dissipate by age five, there is some evidence that full-time maternal employment coupled with informal care increases the risk of being overweight at both ages three and five for children of higher-educated mothers. An assessment of selection bias finds that the estimates of full-time employment combined with formal childcare by well-educated mothers are a lower bound, such that the true effect on child weight may be understated.

Conclusions
The findings for Ireland are consistent with studies from the United States and the United Kingdom, and are in contrast to findings from the rest of Europe, suggesting the role of institutional factors, such as the lack of subsidised, universal, high-quality childcare.

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.

Differentials in physical activity (PA) between social and economic groups has been shown to contribute significantly to social gradients in health and life expectancy, yet relatively little is known about why differentials in PA emerge. This paper uses longitudinal data on a nationally representative sample of 6,216 young people aged between 9 and 18, from Ireland, to measure the role of family, school and neighbourhood level factors in accounting for differentials in PA trajectories between groups of young people, defined by level of maternal education, whilst adjusting for the individual characteristics of the young person (sex, age, personality, body mass index and health-status). Levels of PA fall significantly across the sample between 9 and 18, and the decline in PA is larger for the children of lower educated mothers. We find a clear gradient in PA at each age by maternal education for both males and females. Descriptive analyses found social gradients in the majority of our risk factors. Using multi-level, linear spline regression models to decompose differentials between groups, we find that family-level mechanisms account for the biggest proportion of the differential in PA for both males (50.8%) and females (35.1%). Differences in income across maternal education categories accounted for 24.1% of the differential for males and 14.7% among females, making it the second most effective mechanism in explaining the social patterning of PA. Neighbourhood-level processes resulted in a modest reduction in the same differential, while school level processes had the effect of equalising differences in PA across maternal education groups.

Given growing concerns about disadvantaged boys’ achievement and disengagement from learning, this paper investigates differences in reading ability by gender and social origin. It uses data from the Growing Up in Ireland study to investigate how parents’ approach to learning at home and children’s exposure to early care and education contribute to these differences. We find that both children’s gender and their family’s social class influence their cognitive development between age 3 and age 9, though the effects are additive, with little variation in the gender gap across social class groups. Parents from more advantaged social classes read more to their 3-year-old children than other parents, yet by age 5, when most children have started primary school, these class differences in parental reading are much lower. Parental reading, ECCE participation and length of primary school exposure were found to facilitate language development and partly explain differences in reading scores at age 9, although strong direct effects of social class remained, even accounting for vocabulary score at age 3. The benefits from parental reading, ECCE and exposure to school are broadly similar for boys and girls, though there is some evidence that boys benefit more than girls from longer exposure to school.

Both psychological and sociological accounts have suggested that the home learning environment play an important role in children’s cognitive development and may provide insights into inequalities in cognitive outcomes. Using the infant cohort of the Growing Up in Ireland Study (GUI), this chapter investigates firstly if differences in the home learning environment at age three helps to explain the social gradient in childhood cognitive outcomes, measured as expressive vocabulary, at age five; and second, can childcare outside the home compensate for a poor home learning environment? Home learning environment is measured as the number of children’s books in the home and a combined index of parental activities with the child that includes reading, crafts and games. A rich home learning environment at age 3 is associated with higher vocabulary scores at age 5 years for all children. The children of lower educated parents tend to live in poorer home learning environments, and this partly explains their lower vocabulary scores at age 5. The chapter also provides some evidence that centre-based childcare was associated with an increase in vocabulary score for children from poor home learning environments. However, this effect is very small and only slightly reduces the gap in vocabulary scores between children from a rich and poor home learning environment.