Aim: This study compared mental health after parental separation in 7-year-old children living in joint physical custody with sole physical custody family arrangements.

Methods: The study population included 39 661 children from the Danish National Birth Cohort, living in a nuclear family at age 6 months. Child mental health was measured at age 7 years with maternal reports of the Strength and Difficulties Questionnaire (SDQ) operationalised as a high total score. Associations between living arrangements and mental health were analysed using logistic regression models, taking into account early childhood indicators of family relations, parental mental health and socioeconomic conditions.

Results: There were no statistically significant differences between the living arrangements after parental separation with joint physical custody having an odds ratio (OR) of 1.37 (95% CI 1.10–1.70), sole physical custody without a new partner OR 1.33 (95% CI 1.19–1.47) and OR 1.55 (95% CI 1.30–1.84) for sole physical custody with new partner, with children in a nuclear family as reference.

Conclusion: This study indicates that living arrangements after parental separation have a minimal influence on child mental health at age 7 years.