Background An emerging body of literature suggests there is a relationship between a pregnant woman's psychological wellbeing and the development of maternal-fetal attachment (MFA) and early postpartum bonding. The nature of this relationship is not well understood because of the limited theoretical framework surrounding the construct of MFA and variations in study methods and data collection points. In this systematic review, we synthesize the published literature to determine the nature of the relationship from the antenatal to early postnatal period and to provide recommendations for future research and clinical practice. Method Using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) approach, four electronic databases were searched for peer-reviewed empirical studies, published in English. Articles were considered for inclusion if data was collected on at least one domain of maternal wellbeing/mental health and MFA during pregnancy or MFA during pregnancy and the mother-infant relationship during the early postpartum period (up to 12 weeks). No date parameters were applied to the search strategy. The review was registered with PROPSERO (registration number: CRD42018096174). Results 25 studies examining maternal mental health and MFA/postpartum bonding were selected for inclusion in this review. Key findings identified from the review were: a need to validate existing mental health measures or develop new measures specific for use in antenatal populations; inconsistencies in data collection points throughout pregnancy and postpartum; a lack of consensus about the construct of MFA and the way it is assessed; and a continued focus on postpartum outcomes. Conclusion Scientific gaps remain in our understanding of the relationship between maternal mental health and both MFA and postpartum bonding which limit our theoretical understanding of the MFA construct. Recommendations for future research are to employ prospective longitudinal designs that span the full pregnancy and postpartum period, and for consistency in the terminology and methodology used when considering MFA. A re-focus of research attention on the theory behind MFA will allow a richer and more holistic account of the emerging relationship between mother and baby.