Background: Post-delivery period could be characterized by psychological distress (e.g., anxiety, sadness, and irritability), leading to post-partum depression (PPD). Objective: The present clinical study assess the effect of probiotic supplementation containing Limosilactobacillus reuteri PBS072 and Bifidobacterium breve BB077 (4x109 CFU/day) on mother’s mood and breastfeeding quality during the first trimester after delivery. Methods: A Randomized Double Blind Controlled (RDBPC) trial has been carried out in 200 healthy new mothers divided into an active group taking a supplement containing Limosilactobacillus reuteri PBS072 and Bifidobacterium breve BB077 (4x109 CFU/day) plus multivitamins, and a control group (multivitamin complex only) for 90 days. Symptoms related to maternal depression and breastfeeding quality were evaluated at days 45 and 90 by Edinburgh Postnatal Depression Scale (EPDS) and Breastfeeding Self-Efficacy Scale Short-Form (BSES-SF). Results: At days 45 and 90, probiotic treatment significantly ameliorated the mothers’ mood compared to the control treatment (p<0.001). Likewise, breastfeeding quality and baby’s cries significantly improved in the probiotic group (p<0.001). Conclusions: Microbiota alterations could influence post-delivery woman’s mental state. According to our results, L. reuteri PBS072 and B. breve BB077 are potential candidates able to improve stress resilience in the post-partum period.