Heart rate modifications related to spontaneous body movements in sleepingpremature and full-term newborns

Heart rate (HR) acceleration is an essential mechanism for adaptation to ch anges in hemodynamic and energetic needs resulting from body movements. To evaluate age-related development of coupling between spontaneous movement a nd HR changes, we performed polysomnographic recordings in 20 clinically an d neurologically normal newborns including 10 premature (31- to 36-wk gesta tional age, wGA) and 10 full-term (38- to 41-wk gestational age) infants. R ecordings were sampled at 286 Hz and processed using a signal-to-noise rati o algorithm for QRS complex detection. Movements were automatically detecte d and the logical signal obtained was sampled at QRS fiducial points and wr itten in the attributes of each QRS. The study included the 402 movements t hat were less than 30 s in duration and were neither preceded nor followed by another movement or by a respiratory event (pause, sigh). The amplitude of movement-induced HR acceleration was significantly lower in premature co mpared with full-term newborns (p < 0.01). This difference persisted when t he other factors influencing the HR response (basal HR, movement duration, and amplitude) were taken into consideration. Our data identify HR accelera tion induced by spontaneous body movements as a fundamental reflex response that develops with gestational age from premature to full-term newborns.