BACKGROUND: Socioeconomic deprivation has been linked to negative child developmental outcomes including brain development, psychological well-being, educational attainment, and social-emotional well-being. Maternal mental health has also been linked to mothers' parenting practices and their children's developmental outcomes. However, limited evidence exists regarding the role of maternal mental health (prenatal and postnatal) in the association between socioeconomic deprivation and children's developmental outcomes. METHODS: We examined the potential role of maternal mental health in the association between socioeconomic deprivation (SED) and child development outcomes. We used a large linked administrative health dataset covering children born between 2011 and 2015 in Greater Glasgow and Clyde, Scotland. Of the 76,483 participants, 55,856 mothers with matched children's developmental outcome data were included. A mediation analysis model, adjusted for confounders and covariates, was used. RESULTS: Maternal mental health assessed by a history of hospital admissions mediated, but to a small extent, the relationship between SED and children's developmental outcomes. The average direct effect (ADE), of SED in the first model with a history of hospital admissions, was ADE: ES = - 0.0875 (95% CI = - 0.097, - 0.08
p <
0.001) and ACME: ES = - 0.0002 (95% CI = - 0.001, - 0.0001
p = 0.01). The proportion mediated by the history of mental health admission was 0.3%. CONCLUSION: The association between SED and children's developmental outcomes appears to be partially mediated by maternal mental health, although the proportional-mediated effect was very small.