UK Millennium Cohort Study Research Articles

The well-being of children in the face of socio-economic deprivation and family instability

This paper explores the role of parenting practices in promoting the well-being of children growing up in conditions of socio-economic deprivation and family instability. Using data collected for the UK Millennium Cohort Study, a multi-dimensional approach is adopted in conceptualising family adversity and children’s well-being. The effect of income poverty on children’s cognitive, social and emotional adjustment is assessed, considering several related adverse factors, such as family demographics, family instability, housing, and area deprivation, to evaluate their independent and combined risk effect. The findings suggest that persistent and intermittent poverty are significantly associated with poorer academic attainment and socio-emotional behaviour adjustment of young children. Family structure and instability show an independent risk effect, especially regarding social behaviour adjustment. Generally, the combined effect of socio-economic and family-related risk factors on children’s adjustment is stronger than individual effects. Parenting practices do not completely mediate the impact of family adversity on children’s adjustment across domains but show independent and beneficial effects -in particular regarding the quality of the parent-child relationship. Adopting a multi-dimensional approach facilitates a better understanding of independent and cumulative risk effects and enables the unpacking of differential effects of parenting practices.

Additive quantile regression for clustered data with an application to children's physical activity.

Additive models are flexible regression tools that handle linear as well as non-linear terms. The latter are typically modelled via smoothing splines. Additive mixed models extend additive models to include random terms when the data are sampled according to cluster designs (e.g. longitudinal).These models find applications in the study of phenomena like growth, certain disease mechanisms and energy expenditure in humans, when repeated measurements are available. We propose a novel additive mixed model for quantile regression. Our methods are motivated by an application to physical activity based on a data set with more than half a million accelerometer measurements in children of the UK Millennium Cohort Study. In a simulation study, we assess the proposed methods against existing alternatives.

What if all children achieved WHO recommendations on physical activity? Estimating the impact on socioeconomic inequalities in childhood overweight in the UK Millennium Cohort Study.

BackgroundThe World Health organization (WHO) recommends that children engage in 60 min daily moderate-to-vigorous physical activity (dMVPA). Just half of children in the UK achieve these levels (with similarly low levels in other high-income countries). Thus, the dMVPA target is a focus of national obesity strategies. However, the potential impact of increased physical activity on prevalence and inequalities in childhood overweight is unknown. Using objective data from the Millennium Cohort Study (∼18 000 children born 2000–02) we simulated a series of hypothetical physical activity intervention scenarios: achievement of the target, and more realistic increases demonstrated in trials.MethodsPredicted probabilities of overweight and obesity (using measured heights and weights at age 11) were estimated in multinomial marginal structural models, adjusting for dMVPA (measured with accelerometers at age 7) and confounding. Inequalities were assessed according to household income quintiles [risk ratios (RRs) and risk differences (RDs)]. Intervention scenarios were simulated by re-estimating predicted probabilities of overweight/obesity after manipulating (increasing) dMVPA by varying amounts, for different eligibility criteria and with varying uptake. Analyses included 6493 children with accelerometer data. Survey weights and multiple imputation addressed sampling design, attrition and item missingness.ResultsIn all, 27% children were overweight/obese, with relative and absolute inequalities in the expected direction; 51% children were achieving 60 min dMVPA, with those from the lowest income quintile achieving, on average, 3 min more dMVPA than those from the highest income quintile. A simulation of universal achievement of the dMVPA target reduced the prevalence of overweight/obesity to 22%, but increased relative inequalities (absolute inequalities were unchanged). Smaller increases in dMVPA (informed by intervention evidence) did little to reduce prevalence or inequalities, even when targeting high-risk groups.ConclusionsUniversal achievement of the WHO dMVPA target, if attainable, would reduce prevalence of childhood overweight and obesity but not inequalities. Scale-up of more realistic interventions would have limited impact.

Social Media Use and Adolescent Mental Health: Findings From the UK Millennium Cohort Study

BackgroundEvidence suggests social media use is associated with mental health in young people but underlying processes are not well understood. This paper i) assesses whether social media use is associated with adolescents' depressive symptoms, and ii) investigates multiple potential explanatory pathways via online harassment, sleep, self-esteem and body image. MethodsWe used population based data from the UK Millennium Cohort Study on 10,904 14 year olds. Multivariate regression and path models were used to examine associations between social media use and depressive symptoms. FindingsThe magnitude of association between social media use and depressive symptoms was larger for girls than for boys. Compared with 1–3 h of daily use: 3 to <5 h 26% increase in scores vs 21%; ≥5 h 50% vs 35% for girls and boys respectively. Greater social media use related to online harassment, poor sleep, low self-esteem and poor body image; in turn these related to higher depressive symptom scores. Multiple potential intervening pathways were apparent, for example: greater hours social media use related to body weight dissatisfaction (≥5 h 31% more likely to be dissatisfied), which in turn linked to depressive symptom scores directly (body dissatisfaction 15% higher depressive symptom scores) and indirectly via self-esteem. InterpretationOur findings highlight the potential pitfalls of lengthy social media use for young people's mental health. Findings are highly relevant for the development of guidelines for the safe use of social media and calls on industry to more tightly regulate hours of social media use. FundingEconomic and Social Research Council.

Maternal mental health at 5 years and childhood overweight or obesity at 11 years: evidence from the UK Millennium Cohort Study

Background/objectivesMaternal psychological distress is associated with a range of adverse child outcomes. We sought to determine whether children’s exposure to medium or severe distress at 5 years was associated with increased risks of overweight and obesity when they were aged 11 years. We also investigated whether any association was attenuated after accounting for potential confounding and mediating factors.Subjects/methodsWe analysed data from the UK Millennium Cohort Study, a nationally representative sample with data collected throughout childhood, imputing missing covariates (analytic sample: n = 9206). Multinomial regression was used to examine whether maternal psychological distress (Kessler-6 scale, using medium and severe score thresholds) at 5 years of age predicted children’s objectively measured overweight and obesity at 11 years, adjusting for sex and ethnicity. We then carried out a series of models incorporating potential confounders (early life and socio-demographic, recorded at 9 months) and mediators (physical activity and dietary factors, at 7 years) in turn, and then simultaneously.ResultsA third of mothers reported distress when their child was aged 5 years (29% medium; 4% severe distress), and over a quarter of children were overweight at 11 years (22% overweight; 6% obese). Risks of obesity at 11 years increased with severity of maternal distress at 5 years (medium distress: relative risk ratio (RRR) = 1.43, 95% confidence interval [CI] 1.17–1.75; severe RRR = 2.27, CI 1.42–3.63). Adjusting for each set of explanatory factors in turn (particularly early years and socio-demographic confounding factors) reduced but did not eliminate these elevated risks. However, risks were attenuated in the fully adjusted model (medium: RRR = 1.14, CI 0.92–1.41; severe: RRR = 1.26, CI 0.75–2.11).ConclusionsWe demonstrated that maternal psychological distress, particularly if severe, at 5 years was associated with risk of obesity (but not overweight) at 11 years. Accounting for potential explanatory factors attenuated this association to non-significance, suggesting a range of mechanisms may be implicated. Future research should seek to disentangle the potentially complex pathways linking explanatory factors, maternal distress and child obesity.

Risk of exposure to air pollution among British children with and without intellectual disabilities.

Exposure to outdoor air pollution is a well-established risk factor for a range of adverse health conditions. No previous study has quantified the extent to which children with intellectual disability (ID) may be exposed to outdoor air pollution. Secondary analysis of data extracted from the UK's Millennium Cohort Study, a nationally representative sample of over 18000 UK children born 2000-2002. Averaging across ages, children with IDs were 33% more likely to live in areas with high levels of diesel particulate matter, 30% more likely to live in areas with high levels of nitrogen dioxide, 30% more likely to live in areas with high levels of carbon monoxide and 17% more likely to live in areas with high levels of sulphur dioxide. Levels of exposure to outdoor air pollution among children with ID are significantly higher than those of families of children without ID. Exposure to outdoor air pollution may be one of the pathways that contributes to the health inequities experienced by people with IDs.

Simulating the impact of poverty reduction on social inequalities in adolescent mental health in the UK: a causal mediation analysis using the UK Millennium Cohort Study

BackgroundAdolescent mental health is poor in the UK, with higher prevalence of poor mental health in adolescents living in poverty. However, little experimental evidence exists to understand the potential impact of poverty reduction on inequalities in mental health in the UK population. We aimed to fill this gap by assessing the effect of poverty reduction with a hypothetical intervention on adolescent mental health. MethodsWe simulated the effect on inequalities in adolescent mental health of a hypothetical intervention that lifts all families with children out of poverty, using a population-representative sample of 11 564 adolescents followed up to age 14 years in the UK Millennium Cohort Study (MCS). Our measure of socioeconomic conditions (SECs) at birth was maternal education dichotomised as low (GCSE all grades D–G or lower, or no qualifications) versus high (GCSE grades A–C, or above). Our outcome was socioemotional behaviour problems (yes or no) as measured by parent-rated Strength and Difficulties Questionnaire total difficulty score of ≥17. We estimated the controlled direct effect, and proportion eliminated, of SECs on mental health after blocking the mediating pathway, of ever being exposed to poverty (<60% of median of equivalised household income) in all six MCS waves; we used marginal structural models with stabilised inverse probability weights accounting for confounding (exposure–mediator and mediator–outcome). Multiple imputation was used to handle missing data. Findings4105 (35%) of 11 564 of the families were ever exposed to poverty in at least one MCS wave. Compared with adolescents from high SEC families, those from low SEC families had increased risk of socioemotional behaviour problems at age 14 years (relative risk 1·97, 95% CI 1·64–2·37]. When all families were hypothetically lifted out of poverty, the risk of socioemotional behaviour problems at age 14 years was reduced substantially (1·07, 1·03–1·11, proportion eliminated 93%). Our results appear robust in the presence of moderate unmeasured confounding by unknown confounders. InterpretationSocial inequalities in adolescent mental health in the UK could be substantially reduced by lifting families out of poverty. Limitations include the self-reported income measure in the MCS and the assumption of no unmeasured confounding that is required for causal interpretation. FundingFunded by the MRC on a Clinician Scientist Fellowship (MR/P008577/1) (for DT-R and ETCL).

How do adverse childhood experiences explain social inequalities in adolescent health outcomes? Findings from the UK Millennium Cohort Study

BackgroundAdverse childhood experiences are associated with poor subsequent health outcomes, but less consideration has been given to their role in generating health inequalities. We aimed to explore how these experiences mediate the association between childhood socioeconomic conditions (SECs) and adolescent health outcomes. MethodsWe used longitudinal data from the UK Millennium Cohort Study, which is based on 6499 children followed for 14 years. Four outcomes were assessed at age 14 years: socioemotional behaviour problems (Strengths and Difficulties Questionnaire score ≥17); overweight and obese (International Obesity Task Force body-mass index cut off); and risk behaviours (ever drunk alcohol; and ever smoked). The main exposure (relative index of inequality) was based on maternal educational level at cohort child birth. Mediating adverse childhood experiences were identified on the basis of seven risk factors (verbal maltreatment, physical maltreatment, parental drug use [when child aged 5 years]; maternal domestic violence, parental divorce, maternal mental illness, and parental alcohol misuse [when child aged 3 or 5]). We undertook counterfactual mediation analyses to assess the natural direct effect (NDE), natural indirect effect (NIE), total effect (TE), and the proportion mediated via adverse childhood experiences for the association between childhood SECs and our health outcomes, while adjusting for confounding—ie, child sex, maternal ethnicity, and age at birth. Given the complexity of the methods applied, results were presented for the complete case sample, and multiple imputation was used to check differences in descriptive analysis. FindingsOverall 13% (95% CI 8·4–20·4) of the total effect of SECs on adolescent socioemotional behaviour problems was mediated through adverse childhood experiences (NDE relative risk 3·71, 95% CI 2·61–5·27; NIE 1·23, 1·14–1·32; TE 4·56, 3·24–6·42). For overweight and obese, the proportion mediated was 4% (0·8–8·4) and relative risks for NDE, NIE, and TE were, respectively, 2·02 (1·73–2·37), 1·03 (1·01–1·06), and 2·09 (1·78–2·44). There was no evidence of mediation by risk behaviours. There were no significant differences between the descriptive results of the complete and imputed cases. InterpretationA small proportion of the increased risk of mental health problems and overweight and obese in UK adolescents growing up in disadvantaged economic circumstances is explained by exposure to adverse childhood experiences. Self-reported outcomes, missing data, and unmeasured confounding are limitations. FundingPublic Health Research Consortium (for VSS). Medical Research Council Clinician Scientist Fellowship (MR/P008577/1) (for DCT-R and ETCL).

Disciplinary Parenting Practice and Child Mental Health: Evidence From the UK Millennium Cohort Study

To investigate whether a longitudinal association exists between differential disciplinary parenting practices at 3 years of age and later child psychopathology at 11 years. Data were obtained from the Millennium Cohort Study, a UK-wide cohort. Discipline style was assessed using a validated maternal reported questionnaire at 3 years of age for which later outcome data were available. "Active" (including smacking, shouting, and telling off) and "withdrawal" (including ignoring, removal of privileges, and sending to bedroom) approaches were distinguished. Child emotional and behavioral problems were assessed at 3 and 11 years of age using the maternally completed Strengths and Difficulties Questionnaire (SDQ). The independence of associations between early discipline and later child mental health was investigated using mutually adjusted regression analyses and potential reverse causality was considered by looking at changes in SDQ subscale scores from 3 to 11 years. Differential associations with change in child psychopathology according to discipline type were observed. Active and withdrawal forms of discipline were associated with a decrease in conduct problems from 3 to 11 years (active, β=-0.28, 95% CI-0.34 to-0.21, p< .001; withdrawal, β=-0.19, 95% CI-0.24 to-014, p< .001). However, active approaches also were associated with an increase in emotional problems (β= 0.07, 95% CI 0.00-0.14, p= .03) not observed for withdrawal approaches. Different approaches to discipline appear to have differential associations with later child mental health. Further research accounting for a larger number of parent and child characteristics is needed to assess whether such associations are causal.

Cross-sectional associations between body mass index and social-emotional wellbeing among differentially active children.

This study assessed gender-specific associations between body mass index (BMI) and social-emotional wellbeing (SEW) among differentially active seven-year-old children. Data are from wave four of the UK Millennium Cohort Study, collected in 2007-08. Children wore an ActiGraph accelerometer for seven consecutive days and measures of stature and body mass were taken. BMI was calculated from stature and body mass (kg/m2). Parents/carers completed the strengths and difficulties questionnaire (SDQ). A total of 6011 children (3073 girls) had completed data. Mean minutes per day spent in moderate-to-vigorous intensity physical activity (MVPA) were calculated for each child. Gender-specific MVPA quartile cut-off values categorized boys and girls separately into four graded groups representing the least (Q1) through to the most active (Q4) children. Adjusted linear regression analyses examined associations between BMI and SDQ scores. Gender-specific analyses were conducted separately for MVPA quartiles. BMI was positively associated with peer problems for Q1 and Q2 boys and girls, conduct problems for Q2 and Q4 boys, emotional problems and prosocial behaviour for Q2 boys and total difficulty scores for Q1 girls and Q2 boys (P < 0.05). Our results revealed that BMI was positively associated with SEW difficulties among the low active children but not the high active children. Further research examining the concurrent effect of diet and MVPA on child weight status and SEW is needed.

How well can poor child health and development be predicted by data collected in early childhood?

BackgroundIdentifying children at risk of poor developmental outcomes remains a challenge, but is important for better targeting children who may benefit from additional support. We explored whether data routinely collected...

Pre-pregnancy body mass index and breastfeeding initiation, early cessation and longevity: evidence from the first wave of the UK Millennium Cohort Study

BackgroundInternational evidence indicates relationships between pre-pregnancy body mass index (BMI) and breastfeeding behaviours. This study aims to assess associations between key points in the breastfeeding trajectory (initiation, early cessation and...

The role of neighbourhood greenspace in children's spatial working memory.

BackgroundExposure to nature may be particularly beneficial for the brain regions that support spatial working memory, a strong correlate of academic achievement.AimsTo explore whether children living in greener neighbourhoods (wards) have better spatial working memory.SampleDrawn from the UK's Millennium Cohort Study, the sample was 4,758 11‐year‐olds living in urban areas in England.MethodsWe fitted two‐level regression models, with children nested in wards, before and after adjustment for confounders, including poverty, parental education, sports participation, neighbourhood deprivation, and neighbourhood history. Spatial working memory was measured using the Cambridge Neuropsychological Test Automated Battery Spatial Working Memory task. Greenspace was measured as the percentage of greenery in the child's ward.ResultsEven after controlling for confounders, lower quantity of neighbourhood greenspace was related to poorer spatial working memory. Importantly, neighbourhood deprivation did not modify this relationship. Therefore, lower quantity of greenspace was related to poorer spatial working memory similarly in deprived and non‐deprived neighbourhoods.ConclusionsChildren living in greener urban neighbourhoods have better spatial working memory. If this association is causal, then our findings can be used to inform policy decisions about both education and urban planning.

Does environment influence childhood BMI? A longitudinal analysis of children aged 3–11

BackgroundChildhood overweight/obesity has been associated with environmental context, such as green space, gardens, crime and deprivation. This paper assesses the longitudinal association between environment and body mass index (BMI) for...

Parents who exit and parents who enter. Family structure transitions, child psychological health, and early drinking

This paper seeks to extend prior research by exploring whether family structure transition is associated with an increase in early alcohol consumption and whether this association is mediated by; children's socio-emotional problems, providing information on whether the effects of the transition; differ according to the number of changes, the family's initial status, or the time of exposure. The; data have been drawn from the UK Millennium Cohort Study to explore associations framed with; a life-course approach. Our findings suggest that types of family transitions (such as distinguishing; parental exits from and parental entrances to the family) are more important than the number of; family changes during childhood. The results show that moving from a two-parent household to a single-parent household directly increased the probability of being a frequent alcohol consumer among early adolescent boys, whereas the indirect effect on girls was found via socio-emotional difficulties. Our findings also show an increase in socio-emotional and behavioural difficulties in boys due to the entrance of a step-parent only if the transition occurred in the earliest childhood. Indeed, a sensitivity analysis of the time to which the children were exposed to the transition to a new family structure showed stronger effects for those who experienced a family structure change in the early life course, consistent with the cumulative disadvantage process.

The role of intelligence in decision-making in early adolescence.

This study investigated the role of intelligence and its development across childhood in decision‐making in adolescence (age 11 years). The sample was 12,514 children from the UK's Millennium Cohort Study, followed at ages 3, 5, 7, and 11 years. Decision‐making (risk‐taking, quality of decision‐making, risk adjustment, deliberation time, and delay aversion) was measured with the Cambridge Gambling Task. Even after adjustment for confounding, intelligence was positively associated with risk adjustment and quality of decision‐making in both boys and girls. Furthermore, in girls risk adjustment was related positively to IQ gains. Our findings suggest that there are important, substantively, associations between intelligence and adapting behaviour to risk at the cusp of adolescence, the period when the response to risk can shape life trajectories. Statement of Contribution What is already known on this subject In children, intelligence and decision‐making, measured with gambling tasks, are inconsistently linked.This could be due to gambling tasks not separating risk‐taking from contingency‐learning. What the present study adds This study measured 11‐year‐olds’ decision‐making using a gambling task in which probabilities of different outcomes are presented explicitly. IQ was positively associated with risk adjustment and quality of decision‐making.Also significant were IQ gains (for risk adjustment, only in girls).There are links between intelligence and adapting behaviour to statistical risk in children.

Maternal mental health and childhood injury: evidence from the UK Millennium Cohort Study

ObjectiveWe assessed whether maternal mental health problems increased rates for child injury during the preschool years and mid-childhood, and the extent to which associations could be accounted for by a...

Socioemotional wellbeing of mixed race/ethnicity children in the UK and US: Patterns and mechanisms

Existing literature suggests that mixed race/ethnicity children are more likely to experience poor socioemotional wellbeing in both the US and the UK, although the evidence is stronger in the US. It is suggested that this inequality may be a consequence of struggles with identity formation, more limited connections with racial/ethnic/cultural heritage, and increased risk of exposure to racism.Using data from the UK Millennium Cohort Study (n = 13,734) and the US Early Childhood Longitudinal Study-Birth Cohort (n ~ 6250), we examine differences in the socioemotional wellbeing of mixed and non-mixed 5/6 year old children in the UK and US and explore heterogeneity in outcomes across different mixed groups in both locations. We estimate a series of linear regressions to examine the contribution of factors that may explain any observed differences, including socio-economic and cultural factors, and examine the extent to which these processes vary across the two nations.We find no evidence of greater risk for poor socioemotional wellbeing for mixed race/ethnicity children in both national contexts. We find that mixed race/ethnicity children experience socio-economic advantage compared to their non-mixed minority counterparts and that socio-economic advantage is protective for socioemotional wellbeing. Cultural factors do not contribute to differences in socioemotional wellbeing across mixed and non-mixed groups.Our evidence suggests then that at age 5/6 there is no evidence of poorer socioemotional wellbeing for mixed race/ethnicity children in either the UK or the US. The contrast between our findings and some previous literature, which reports that mixed race/ethnicity children have poorer socioemotional wellbeing, may reflect changes in the meaning of mixed identities across periods and/or the developmental stage of the children we studied.

Temporal effects of maternal psychological distress on child mental health problems at ages 3, 5, 7 and 11: analysis from the UK Millennium Cohort Study.

Psychological distress is common among women of childbearing age, and limited longitudinal research suggests prolonged exposure to maternal distress is linked to child mental health problems. Estimating effects of maternal distress over time is difficult due to potential influences of child mental health problems on maternal distress and time-varying confounding by family circumstances. We analysed the UK Millennium Cohort Study, a nationally representative sample with data collected throughout childhood. Adopting a marginal structural modelling framework, we investigated effects of exposure to medium/high levels of maternal psychological distress (Kessler-6 score 8+) on child mental health problems (Strengths and Difficulties Questionnaire borderline/abnormal behaviour cut-off) using maternal and child mental health data at 3, 5, 7 and 11 years, accounting for the influence of child mental health on subsequent maternal distress, and baseline and time-varying confounding. Prior and concurrent exposures to maternal distress were associated with higher levels of child mental health problems at ages 3, 5, 7 and 11 years. For example, elevated risks of child mental health problems at 11 years were associated with exposure to maternal distress from 3 years [risk ratio (RR) 1.27 (95% confidence interval (CI) 1.08-1.49)] to 11 years [RR 2.15 (95% CI 1.89-2.45)]. Prolonged exposure to maternal distress at ages 3, 5, 7 and 11 resulted in an almost fivefold increased risk of child mental health problems. Prior, concurrent and, particularly, prolonged exposure to maternal distress raises risks for child mental health problems. Greater support for mothers experiencing distress is likely to benefit the mental health of their children.

Gestational age at birth and wheezing trajectories at 3–11 years

ObjectiveChildren born preterm have an increased risk of asthma in early childhood. We examined whether this persists at 7 and 11 years, and whether wheezing trajectories across childhood are associated...