External Publications Using GUI Data

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.

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.

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.

The prevalence of low birth weight is an important aspect of public health which has been linked to increased risk of infant death, increased cost of care, and a range of later life outcomes. Using data from a new Irish cohort study, I document the relationship between birth weight and socio-economic status. The association of maternal education with birth weight does not appear to be due to the timing of birth or complications during pregnancy, even controlling for a wide range of background characteristics. However, results do suggest intergenerational persistence in the transmission of poor early life conditions. Birth weight predicts a number of outcomes at age 9, including test scores, hospital stays and health. An advantage of the data is that I am able to control for a number of typically unmeasured variables. I determine whether parental investments (as measured by the quality of interaction with the child, parenting style, or school quality) mediate the association between birth weight and later indicators. For test scores, there is evidence of non-linearity, and boys are more adversely affected than girls. I also consider whether there are heterogeneous effects by ability using quantile regression. These results are consistent with a literature which finds that there is a causal relationship between early life conditions and later outcomes.

Background
The COVID-19 pandemic has been dubbed the “biggest public health crisis since the Second World War”. In Ireland, schools were closed for 141 days, dramatically altering the day to day lives of children in Ireland. This research aimed to evaluate the overall wellbeing of schoolchildren in Ireland and capture the prevalence and factors contributing to poor mental health.

Methods
A cross-sectional study was performed based on data from the Growing Up in Ireland COVID-19 web survey of the ’08 Infant cohort. Mental Health Inventory-5 scores were used to assess children at risk of mental health disorders. Logistic regression examined associations between various demographic and psychosocial factors and risk of mental health disorders.

Results
This study included 2,867 primary caregiver- child dyads. Almost 25% of 12/13-year-olds were at risk of mental health disorders (MHDs). An adjusted logistic regression model found associations between being at higher risk of MHDs and factors such as reduced physical activity levels (OR 1.35, 95% CI 1.10-1.66), spending less time outdoors (OR 1.48, 95% CI 1.18-1.85), increased screen-time (OR 1.35, 95% CI 1.09-1.67) and increased arguments with PCGs (OR 3.44, 95% CI 2.78-4.27). Having a trusted adult confidante reduced the risk of MHD (OR 0.25, 95% CI 0.14-0.45).

Conclusions
The prevalence of 12/13-year olds at elevated risk of MHD was high, indicating an urgent need for enhancement of child and adolescent mental health services in Ireland. Physical activity, time outdoors and supportive relationships with primary caregivers were positively associated with reduced MHD risk.

Key messages

• Children were impacted by the COVID-19 restriction measures in a way that was disproportionate to their risk.
• To reduce the risk of poor mental health outcomes for a generation of “quarantweens” we need to place children front-andcentre of our response as we recover from COVID-19.

It is well established that stressful life events (e.g., family bereavements or moving to a new country) are damaging to psychological health and well-being. Indeed, social relationships are often noted as an important factor that can influence well-being and buffer the negative effects of stress. However, the quality and source of these relationships, particularly for adolescents, are often overlooked. Using the Growing Up in Ireland Survey, a population-based study of 13-year-old Irish adolescents (N = 7,525; 51.1% female), the current study examines the quality of both parent and peer relationships as potential mechanisms explaining the association between stressful life events and psychological well-being indices in adolescents. As expected, results showed that stressful life events negatively impacted the psychological well-being of adolescents. Parallel mediation analyses indicated that both parent and peer relationship quality mediated this association. Further exploratory analyses found that for girls, greater numbers of stressful life events were associated with poorer quality relationships with both their parents and peers, and in turn, these were linked to lower levels of psychological well-being. For boys, this effect was only evident for parental relationship quality, but not peers. The implication of these findings for adolescent’s psychological well-being, particularly for girls, is discussed.

This article explores the role that home-learning activities (HLAs) play in the relationship between social origin and cognitive development using an Irish birth cohort study, Growing Up in Ireland. Numerous studies using different measures of the home-learning environment (HLE) have shown that it has considerable influence on young children’s cognitive development, and that the HLE is often linked to social origin. We find a social gradient in vocabulary even at age 3 years, with the largest gaps for mothers’ education. Family income, mothers’ education, and social class are also associated with vocabulary independently, though these associations are reduced by adding all three measures simultaneously. The extent of HLAs helps explain a very small part of the education differences and none of the income or social class differences in vocabulary. We find some evidence that HLAs may be more salient for children from families with low income and lower social class backgrounds in terms of supporting vocabulary development, thereby compensating somewhat for disadvantage. HLAs also appear to encourage vocabulary development between age 3 and 5, and play a role in reducing the gap in vocabulary between high- and low-income children.

This study reports recent trends in periconceptional folic acid use in Ireland using archived data from Growing Up in Ireland – the National Longitudinal Study of Children. Of a sample of 10,891 mothers, 6,936 (64%) reported taking folic acid before conception and 10,157 (93%) reported taking folic acid during the first trimester of pregnancy. Younger (OR=0.38, 95% CI=0.29-0.50), lower income (OR=0.59, 95% CI=0.51-0.68), lower educated (OR=0.77, 95% CI=0.66-0.89), and single mothers (OR=0.46, 95% CI=0.40-0.52) were less likely to have taken folic acid pre-conception. A similar pattern was found post-conception with younger (OR=0.58, 95% CI=0.40-0.84), lower income (OR=0.40, 95% CI=0.30-0.53), lower educated (OR=0.50, 95% CI=0.38-0.66), and single mothers (OR=0.74, 95% CI=0.60-0.91) less likely to have taken folic acid post-conception. The findings highlight an ongoing need for targeted promotional campaigns to increase supplementation rates among younger and socially disadvantaged mothers.

This nationally representative study of Irish infants explores whether the set of child and environmental factors established as predicting language outcomes aged 3 years would also predict language and communication development as early as age 9 months. Associations between infant and environmental characteristics and infant language outcomes at 9 months, as measured on the ASQ 10-month communication questionnaire, were explored in a series of bivariate logistic regression models and in a fully adjusted multivariable logistic regression model. Infant gender, health, birthweight and temperament were significantly associated with passing the ASQ communication measure at 9 months. Being an only child and having some experience of relative childcare predicted positive communication outcomes. Infants of older mothers and mothers who spoke less to the child while doing other things were significantly less likely to pass. Infants of mothers with the lowest educational level were more likely than their peers to pass at 9 months. Unlike language outcomes at 3 years, low maternal education does not appear to be a risk factor for poorer outcomes at 9 months. This study adds significantly to the infant language development literature by focussing on communication outcomes in early infancy and identifying protective and risk factors at such an early stage.

Anecdotal evidence suggests that grandparents provide a substantial amount of childcare support to parents of infants in Ireland yet there has been little attention to the provision of grandparent childcare at policy level. Using nationally representative data on childcare provision in the Republic of Ireland, this study examined the prevalence of grandparent childcare provision for very young children, and associations between this choice of childcare and key infant, family, and community factors. Using archived data from the Infant Cohort of the Growing Up in Ireland study, descriptive data regarding use of grandparents as childcare providers were outlined. A series of bivariate analyses were then conducted to examine the independent association between a range of infant, family, and community variables and use of grandparent childcare. Finally, a multivariate analysis using binomial logistic regression was used to examine the association of each of these variables in a fully adjusted model. The results show that 38.6% of infants experienced non-parental childcare: 12.4% were looked after by grandparents, 15.7% by other home-based carers and 10.5% in childcare centres such as crèches. Grandparents were the cheapest source of childcare but also provided fewer hours on average. Multivariate analysis indicated the importance of parental income, age, and education in choosing grandparental childcare, with younger, less well-off parents using grandparent childcare more than any other type of childcare. The findings suggest that, whether by choice or by economic pressure, grandparents represent a huge resource in terms of providing childcare for infants. Current childcare policy needs to be cognisant of the significant contribution of grandparents in helping families with young children participate in the labour force. Constraints on the amount of care grandparents are able to provide may have knock-on constraints for parents’ participation in the labour force and earnings.

Keywords
Grandparents, Childcare, Policy, Infants, Ireland