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How do early-life factors explain social inequalities in adolescent mental health? Findings from the UK Millennium Cohort Study
  1. Viviane S Straatmann1,
  2. Eric Lai1,
  3. Theis Lange2,3,
  4. Melisa Claire Campbell1,
  5. Sophie Wickham1,
  6. Anne-Marie Nybo Andersen4,
  7. Katrine Strandberg-Larsen4,
  8. David Taylor-Robinson1
  1. 1 Public Health and Policy, Institute of Psychology Health and Society, University of Liverpool, Liverpool, UK
  2. 2 Center for Statistical Science, Peking University, Beijing, China
  3. 3 Department of Biostatistic, University of Copenhagen, Copenhagen, Denmark
  4. 4 Department of Public Health, Section of Social Medicine, University of Copenhagen, Copenhagen, Denmark
  1. Correspondence to Dr Viviane S Straatmann, Public Health and Policy, University of Liverpool, Liverpool L69 3BX, UK; v.schultz-straatmann{at}


Background Reducing inequalities in adolescent mental health is a public health priority, yet the pathways that link social conditions to mental health outcomes in the early years are unclear. We aimed to evaluate the extent to which early years risk factors explain social inequalities in adolescent mental health in the UK.

Methods We analysed data from 6509 children captured in the UK Millennium Cohort Study. Mental health was assessed through the socioemotional behavioural problems at age 14 (Strengths and Difficulties Questionnaire). The main exposure was maternal education at birth, used as a measure of childhood socioeconomic conditions (SECs), and used to calculate the relative index of inequality. Using causal mediation analysis, we assessed how perinatal, individual child, family, peer relation and neighbourhood-level factors measured up to age 3-mediated the total effect (TE) of SECs on adolescent socioemotional behavioural problems, estimating the proportion mediated and natural indirect effect (NIE) via each block of mediators, and all mediators together.

Results Children of mothers with no qualification were almost four times as likely to have socioemotional behavioural problems compared with degree plus level (relative risk (RR) 3.82, 95% CI 2.48 to 5.88). Overall, 63.9% (95% CI 50.2% to 77.6%) (NIE RR 1.97, 95% CI 1.63 to 2.37) of the TE (RR 4.40, 95% CI 3.18 to 6.07) of social inequalities on risk of adolescent socioemotional behavioural problems was mediated by early-life factors.

Conclusions About two-thirds of the social inequality in adolescent mental health was explained by early risk factors measured by age 3, highlighting the importance of public health interventions in this period.

  • Lifecourse / Childhood Circumstances

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  • Contributors VSS carried out the statistical analyses (supported by EL and TL), drafted the initial manuscript, and reviewed and revised the manuscript. EL, KS-L, TL, MCC, SW and A-MNA participated in the drafting of the initial manuscript, and reviewed and revised the manuscript. Professor DT-R conceptualised and designed the study, coordinated, drafted the initial manuscript, and reviewed and revised the manuscript. All authors approved the final manuscript as submitted and agreed to be accountable to all aspects of the work.

  • Funding This work was supported by the UK Public Health Research Consortium (PHRC). The PHRC is funded by the Department of Health and Social Care Policy Research Programme. The views expressed in this paper are those of the authors and do not necessarily reflect those of the Department of Health and Social Care. Information about the wider programme of the PHRC is available online ( VSS was granted by the Early Career Research Funding 2017 from the University of Liverpool. DT-R is funded by the MRC on a Clinician Scientist Fellowship (MR/P008577/1).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The Millennium Cohort Study (MCS) was approved by the South West and London Multi-Centre Research Ethics Committees (MREC/01/6/19, MREC/03/2/022, 05/MRE02/ for sweeps one, two and three respectively). The MCS obtained informed written consent from parent/guardians of the cohort children in order to participate in the study, children themselves as they grow up and other participants as necessary. For the present study, the MCS has been fully anonymised and did not require additional ethics. More information is available on Shepherd P, Gilbert E. Millennium Cohort Study Ethical Review and Consent (Internet). 2019 (

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available in a public, open access repository.

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