Maternal retention in HIV care is lower for women in the postpartum period than during pregnancy, but the reasons are poorly understood. We examined key differences in barriers to retention in HIV care during and after pregnancy.We conducted semi-structured, in-depth interviews with 30 postpartum women living with HIV. Participants were recruited from two tertiary facilities implementing Option B+ for prevention of mother-to-child HIV transmission in Accra, Ghana. We collected data from mothers who had disengaged from HIV care and those who were still engaged in care. The interviews were analyzed using principles adapted from grounded theory.Participants' experiences and narratives showed that retention in HIV care was more challenging during the postpartum period than during pregnancy. Poor maternal physical health (from birth complications and cesarean section), socio-cultural factors (norms about newborn health and pregnancy), and economic difficulties linked to childbirth (such as unemployment, under-employment, and debt) made the costs of retention in HIV care more economically and socially expensive in the postpartum period than during pregnancy. Some participants also shared that transportation costs and resulting dependence on a partner to pay increased during the postpartum period because of a strong shift in maternal preference for private modes of transportation due to HIV stigma and the desire to protect the newborn. These factors played a larger role in the postpartum period than during pregnancy and created a significant barrier to retention. A conceptual model of how these factors interrelate, the synergy between them, and how they affect retention in the postpartum period is presented.In Ghana, lower retention in HIV care in the postpartum period compared to in pregnancy may be primarily driven by social, economic, and newborn health factors. Multifaceted economic-based and stigma-reduction interventions are needed to increase retention in maternal HIV care after childbirth.