Abstract
Objectives Maternal depression in the postpartum period is prevalent and associated with negative child outcomes, including behavior problems and cognitive delays. Mothers of children admitted directly after birth to the neonatal intensive care unit (NICU) are at even higher risk for depressive symptoms and infants born premature and/or at low birth weight may be more vulnerable to the adverse effects of maternal depression. Understanding mechanisms, particularly modifiable mechanisms, involved in the development or persistence of depressive symptoms is critically important for developing effective treatments. Methods The longitudinal, secondary analysis investigated the role of psychological inflexibility (rigidly avoiding or attempting to control distressing internal experiences, precluding present moment awareness of contingencies and engagement with important values) as a mediator of the relationship between early (1-2 weeks postpartum) and later (3 and 6 months postpartum) depressive symptoms among mothers with an infant in the NICU. Results Psychological inflexibility measured 2 weeks after infant discharge from the hospital fully mediated the relationship between early and later depressive symptoms at 3 months postpartum, with partial mediation at 6 months, while controlling for factors previously found predictive of postpartum depression. Conclusions for Practice Psychological inflexibility may be a mechanism by which postpartum depressive symptoms persist after hospital discharge among new mothers with a NICU infant. Acceptance and Mindfulness therapies which specifically target psychological inflexibility may be promising interventions to reduce depressive symptoms postpartum.