AbstractBackgroundDespite extensive benefits and high intentions, few mothers breastfeed exclusively for the recommended duration. Maternal mental health is an important underlying factor associated with barriers and reduced rates of breastfeeding intent, initiation, and continuation. Given evidence of a bidirectional association between maternal mental health and breastfeeding, it is important to consider both factors when examining the efficacy of interventions to improve these outcomes. The purpose of this manuscript is to review the literature on the efficacy of behavioral interventions focused on both maternal mental health and breastfeeding outcomes, examining the intersection of the two.MethodsThis systematic review was completed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. Studies were selected if they were available in English, used primary experimental design, and used a behavioral intervention type to examine maternal mental health and breastfeeding outcomes. Articles were identified from PubMed, CINAHL, Embase, and PsycINFO from database inception to 3 March 2022. Study quality was assessed using the Cochrane Risk of Bias tool. Results were synthesized by intervention success for 1. Mental health and breastfeeding, 2. Breastfeeding only, 3. Mental health only, and 4. No intervention effect. PROSPERO CRD42021224228.ResultsThirty interventions reported in 33 articles were identified, representing 15 countries. Twelve studies reported statistically significant positive effect of the intervention on both maternal mental health and breastfeeding; most showing a decrease in self-report depressive and/or anxiety symptoms in parallel to an increase in breastfeeding duration and/or exclusivity. Common characteristics of successful interventions were a) occurring across pregnancy and postpartum, b) delivered by hospital staff or multidisciplinary teams, c) offered individually, and d) designed to focus on breastfeeding and maternal mental health or on breastfeeding only. Our results are not representative of all countries, persons, experiences, circumstances, or physiological characteristics.ConclusionsInterventions that extend the perinatal period and offer individualized support from both professionals and peers who collaborate through a continuum of settings (e.g., health system, home, and community) are most successful in improving both mental health and breastfeeding outcomes. The benefits of improving these outcomes warrant continued development and implementation of such interventions.Systematic review registrationPROSPERO CRD42021224228.