Nakamura Y, et al. - In this case-control study involving 36 pregnant women (18 cases and 18 controls determined after childbirth), researchers used methylation analysis and peripheral blood to search for biomarkers that could contribute to the development a predictive method for postpartum depression (PPD), a major depressive disorder that occurs after childbirth. Using linear regression analysis, the association of DNA methylation status at each DNA methylation site with PPD was evaluated. The difference in methylation frequency between the postpartum non-depressed group and the postpartum depressed group was small in the analysis with the postpartum depressed state as an independent variable, and sites with genome-wide significant differences were not verified. The authors reported four gene ontology terms, including axon guidance, related to postpartum depression after analysis by The Database for Annotation, Visualization and Integrated Discovery 6.8. These findings can assist in developing an objective predictive method for PPD.