Research points to the significant impact of maternal distress on the parentinfant relationship and infant development. The Newborn Behavioral Observations (NBO) is a brief intervention supporting the infant, the parent and their relationship. This randomized controlled trial examined the effectiveness of the NBO in a population with antenatal distress and risk of postnatal depression (PND). Pregnant, first-time mothers with current anxiety or depression symptoms or past mental illness were recruited from two Australian hospitals. Participants received three NBO sessions in the first month of life plus treatment as usual (TAU), or, TAU-only. Outcomes assessed at infant age 4 months included mother-infant interaction quality; maternal anxiety and depression symptoms;This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.