Assessing the average causal effect of maternal postpartum depression diagnosis on subsequent child development at age five years: A causal analysis using the All Our Families cohort and administrative data in Alberta, Canada

Purpose Postpartum depression (PPD) is a prevalent public health issue impacting nearly 15% of mothers in the first year following childbirth. PPD has implications for the health and mental health of the mother and downstream effects for the development of her offspring. Limited research to date has investigated whether clinical PPD diagnosis contributes to child development. This study aims to understand the average causal effect of maternal PPD diagnosis on child development at age five years. Methods A causal framework was used to identify study assumptions and inform this analysis. Using longitudinal data from the All Our Families prospective cohort from Calgary, Canada (n = 2784) linked to provincial inpatient and physician claims health administrative data, we used an augmented inverse propensity weighted approach to estimate the average causal effect of maternal PPD diagnosis on child development, measured using the Ages and Stages Questionnaire at age five. Missing values were estimated using multiple imputation. Results Findings indicate that relative to mothers not diagnosed with PPD, children whose mothers were diagnosed received similar mean scores, on average, across all domains of development (communication, gross motor, fine motor, problem solving, and personal social) at age five, suggesting no differences in the achievement of child developmental milestones. Conclusion This study highlights the potential for diagnosis of maternal PPD in reducing subsequent risks for child development. Further research is warranted to determine whether these results are generalisable beyond the current study context.