Perinatal depression affects millions of people worldwide and is a contributing factor to sex-related health disparities. While the etiology has been comprehensively explored, it remains unclear. This chapter provides an overview of bodily functions associated with the perinatal period and with depression. Further, a handful of risk factors have been identified, where the most pronounced ones are previous depressive episodes, lack of social support, and partner violence. This chapter goes on to discuss risk factors related to sociodemographic, psychological, and pregnancy and obstetric elements. Studies indicate that perinatal depression is both preventable, intervenable, and treatable. Hence, identifying risk factors and biomarkers for early detection and prevention is crucial. While the search for biomarkers has been ongoing for decades, no clinically meaningful marker has been established yet. This chapter provides insight to biomarkers investigated as potential contributors and predictors of perinatal depression.