Introduction: Periodic breathing (PB) is considered physiological in the neonatal period but must disappear in the first months of life. Few data regarding PB after the neonatal period are available. The objective of this study was to describe the clinical and polysomnographic characteristics of infants presenting with PB after the age of 1 month. Methods: This French multicenter retrospective case series included infants born at term between 2012 and 2021, without underlying disease, and who presented during a polysomnography (PSG) recording more than 1% of PB after 1 month of life. Results: Overall, 10 infants were included, they underwent a PSG for brief resolved unexplained event, desaturation, pauses in breathing, cyanosis, and/or signs of respiratory distress. The percentage of total sleep time spent with PB was 18.1% before 3 months (n=7), 4.7% between 3 and 6 months (n=10), 7.1% between 7 and 12 months (n=2), and 0% after 12 months (n=2). During the first PSG, ≥ 3% desaturations were observed in 77% to 100% of the PB episodes. At the first PSG, 9/10 infants had an obstructive apnea hypopnea index > 10/h and 5/10 had a central apnea index > 5/h. Gastro-esophageal reflux (GER) was suspected in 8/10 infants. All infants showed improvement in initial symptoms during the first year of life. Conclusion: Although PB is rare after 1 month of age, the present study shows that when present, PB is most frequently associated with obstructive and/or central apnea syndrome in term infants without comorbidities other than GER.