Background: Pregnancy can be a stressful time for many women; however, it is unclear if higher stress and depressive symptoms are associated with poorer diet quality during pregnancy.Objective: The aims for this narrative review were to (1) synthesize findings of original, peer-reviewed studies that examined associations of stress and/or depressive symptoms with diet quality during pregnancy; (2) review the measurement tools used to assess stress, depressive symptoms, and diet quality; (3) identify current gaps in the extant literature; and (4) offer recommendations for future research.Methods: A search strategy was used to identify peer-reviewed manuscripts published between January 1997 and October 2018, using the following databases: PubMed, CINAHL Complete, PsycINFO, Academic Search Complete, and Psychology & Behavioral Sciences Collection. The search was updated December 2019. Two reviewers independently assessed title, abstract, and full-text of the studies that met the inclusion criteria. Data were extracted and a quality assessment was conducted.Results: Twenty-seven observational studies were identified in this review (21 cross-sectional and 6 longitudinal). In 22 studies, higher stress and/or depressive symptoms were associated with poorer diet quality or unhealthy dietary patterns; 5 studies found no association. Findings are mixed and inconclusive regarding the relationship among stress, depressive symptoms, and food groups related to diet quality and frequency of fast-food consumption.Conclusions: The current data suggest stress and depressive symptoms may be a barrier to proper diet quality during pregnancy; however, variability in the assessment tools, timing of assessments, and use of covariates likely contribute to the inconsistency in study findings. Gaps in the literature include limited use of longitudinal study designs, limited use of comprehensive diet-quality indices, underrepresentation of minority women, and lack of multilevel theoretical frameworks. Studies should address these factors to better assess associations of stress and/or depressive symptoms with diet quality during pregnancy.