Respiratory indices during sleep in healthy infants: A prospective longitudinal study and meta-analysis

Study objectives Healthy infants may have a greater apnea hypopnea index (AHI) than older children during the newborn period, but the trajectory of these sleep-related events beyond the first month of life is poorly understood. In this study, we evaluated the longitudinal changes in respiratory indices during sleep in healthy infants during the first six months of life. Methods Single-center prospective cohort study. Thirty healthy infants underwent overnight in-lab polysomnography at one and five months of age and findings were compared between assessments. Systematic review of studies evaluating infant polysomnography and meta-analysis was conducted. Results At one month of age, total AHI, obstructive AHI, and central AHI model-adjusted means (95% confidence interval) were 16.9 events/hour (12.2, 21.5), 10.2 events/hour (7.4, 13.1), and 6.6 events/hour (4.2, 9.0), respectively. 16.8% of events were obstructive apneas and 36.1% central apneas. By five months of age, there were significant reductions in each index to 4.1 events/hour (3.2, 5.0), 1.9 events/hour (1.4, 2.4), and 2.2 events/hour (1.6, 2.9), respectively (p < 0.001 for each), and a lower proportion of events were obstructive apneas (8.6%, p = 0.007) and a greater proportion central apneas (52.3%, p = 0.002). Meta-analysis found high AHI in infants with significant heterogeneity. Conclusions Central AHI and obstructive AHI are greater in healthy newborns than older children. There is a significant spontaneous reduction in events and change in type of events in the first six months of life in this low-risk population. These findings may serve as a reference for clinicians evaluating for obstructive sleep apnea in infants.