LAUSR

Abstract Dyadic behavioral synchrony is a complex interactional process that takes place between the mother and her infant. In the first year of life, when the infant is prelinguistic, processes such as synchrony enable the dyad to communicate through shared behavior and affect. To date, no systematic review has been carried out to understand the risk and protective factors that influence behavioral synchrony in the mother–infant dyad. The aim of this review was to identify and evaluate the factors that influence behavioral synchrony in the mother–infant dyad, when the infant is between 3 and 9 months old. Key electronic databases were searched between 1970 and April 2021, and 28 eligible studies were identified for review. As the results were largely heterogeneous, four subgroups of factors were identified: (i) infant demographics, (ii) physiological factors, (iii) maternal mental health, and (iv) miscellaneous factors. Identified risk factors and covariates suggest that social determinants of health, underpinned by biological factors, play a large role in influencing behavioral synchrony within the dyad. Implications for the need to identify additional risk and protective factors, as well as design support for at‐risk families are discussed.