Background. Seasonal Respiratory syncytial virus (RSV) bronchiolitis continues to be a global health concern. There are no vaccines available against RSV; passive and temporary immunization strategies i.e., monoclonal antibodies (Ab), are used to protect vulnerable newborns. Several studies suggested that maternal anti-RSV Ab transferred through the placenta or via breast milk may protect the baby against severe bronchiolitis. Hypothesis. Maternal RSV exposure during pregnancy influences the concentration of RSV Ab transferred from the mother to the offspring. Aim. To evaluate anti-RSV Ab values in maternal blood, cord blood and breast milk samples, according to RSV season. Methods. Mother-infant dyads were enrolled at Policlinico Umberto I in Rome, Italy, between Nov 2021 and Jan 2023 and divided in Group E, recruited during the RSV epidemic period (Nov-Jan) and Group nE, recruited outside the epidemic period (Feb-Oct). Anti-RSV IgG and IgA were detected by ELISA test in samples of maternal peripheral blood, umbilical cord blood and breast milk collected after delivery. Results. Eighty-eight dyads were enrolled; 30 dyads were assigned to Group E and 58 to Group nE. The mean anti-RSV IgG values in maternal and cord blood samples of Group E were significantly higher than in Group nE, (53.3 RU/ml vs 82.6 RU/ml; p=0.002 and 80.2 RU/ml vs 103 RU/ml; p=0.011 respectively). Similarly, mean anti-RSV IgA values in breast milk were higher in Group E than in Group nE (0.74 sample OD/Calibrator OD vs 1.15 sample OD/Calibrator OD; p=0.09). Conclusions. Birth season influences the level of neonatal RSV-specific antibodies received by the mother. Our results could guide future RSV vaccination strategies.