DNA methylation studies of depression with onset in the peripartum: A critical systematic review

Objective: Major depression with peripartum onset (MDP) has been associated with multiple adverse offspring health outcomes. The biological mechanisms underlying this relationship remain unclear, but DNA methylation (DNAm) represents a plausible mechanism for mediating MDP exposures and changes in offspring development, behavior, and health. Advances in DNAm research necessitate reevaluating the MDP-DNAm literature to determine how well past studies conform with current best practices. Method: Five databases were searched to identify studies of prenatal-onset MDP and DNAm. Quality scores were assigned to each article independently by two raters using a novel scale specific for MDP-DNAm research. Results: Nineteen studies met inclusion criteria. Quality scores ranged from 10 to 17 out of 24 points (M = 12.8; SD = 1.9), with higher scores indicating increased study rigor. Poor covariate reporting was the most significant contributor to lower scores. Conclusion: No longitudinal MDP-DNAm studies exist. Earlier MDP-DNAm studies should be interpreted with caution, and future research must commit to sharing methodology and data to facilitate cross-study comparisons and maximize dataset utility.