title: Biological rhythm development in preterm infants: does health status influence body temperature circadian rhythm?
abstract: Twenty-six preterm infants, postconceptional age from 28 to 35 weeks and postnatal age approximately 14 days, were included in a study of the development of temperature circadian rhythm. Insulated abdominal skin temperature and incubator air temperature were recorded continuously at 1-min intervals for 24 hr. Using cosinor analysis, cycle mesor, amplitude, and acrophase were determined. Initial results from regression analysis did not confirm a predicted linear relationship between postconceptional age and amplitude; however, dividing the sample according to health status into sick (N = 15) and not sick (N = 11) groups revealed differing regression models. For not sick infants, amplitude increased with postconceptional age (R(2) =.405), whereas no relationship was found between postconceptional age and cycle amplitude in sick infants (R(2) =.069). These results indicate that healthy preterm infants demonstrate emergence of circadian temperature rhythm. Implications include potential time-based periods of vulnerability, overheating and hyperthermia, and management of incubator operation.
authors.affiliation: University of Washington, Box 357262, Seattle, 98195-7262, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Thomas
mesh_terms: D001831:Body Temperature / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006304:Health Status; D006801:Humans; D007186:Incubators, Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D012881:Skin Temperature