Abstract / Summary
Approximately one in ten live births is preterm ( < 37 weeks gestational age), placing these infants at elevated risk because of immature physiology. Analysis of movement patterns in the Neonatal Intensive Care Unit (NICU) is essential for detecting complications, yet current monitoring approaches remain limited. Using routine photoplethysmography (PPG), we extracted movement bouts from 65 preterm infants (47 without health complications, 18 with severe neurological conditions) across 50 days using a validated algorithm. Movement actigraphy was summarized using three novel metrics: (1) percent time moving per day across postmenstrual age, (2) daily distributions of movement durations quantified by power law exponents, and (3) ultradian movement cycles across 24 hours. While percent time moving did not change with age, power law exponents scaled linearly with age, indicating longer movements with maturation. Daily movement activity revealed 3-hour ultradian cycles corresponding to NICU feeding schedules, alongside an anticipatory rise in spontaneous motor activity before feeding. Infants with neurological complications, including two individual case studies, showed deviations in activity patterns when compared to uncomplicated infants. These results suggest that longitudinal movement tracking using routine sensors reveals systematic activity patterns and offers a scalable clinical tool for evaluation of health in this high-risk population.