Factors affecting the development of night time temperature rhythms.

Abstract

The rectal temperature of 26 infants between 6 and 16 weeks old was monitored continuously for one night each week. Rectal There appeared, however, to be considerable individual differences in the age at which this pattern appeared. This paper reports longitudinal studies of individual infants which confirm these differences, and shows some factors affecting the timing of development of night time temperature rhythms.Subjects and methods Thirty normal healthy full term infants were recruited at or just after birth by liaison with general practitioners and health visitors in Leicestershire. Parents gave informed consent to weekly overnight recordings of body temperature from 6 to 16 weeks of age. Basic perinatal data were collected at the time of recruitment and parents were provided with a diary to record prospectively any episodes of illness in the infant.Once each week from 6 weeks' old the infant was visited at home in the evening, weighed naked, and data collected on the current feeding regimen, other aspects of parental care, and the health of the infant and family. Probes were then attached to record body temperature. A soft probe, inserted 5 cm from the anal margin, recorded rectal temperature and a skin thermistor measured surface temperature on the skin. Only rectal temperature data are described here. A third probe measured ambient temperature near the infant. All three probes were connected to a Grant Squirrell data logger, set to sample at one minute intervals throughout the night. These techniques are safe,' and full ethical approval was obtained for the study.Parents were asked to keep a detailed diary of all events throughout each night of recording, including feeds, nappy changes, periods of waking, and administration of any drugs. Note was also made of infant's clothing and bedding so that a thermal insulation or 'tog' value could be calculated according to tables provided by the Shirley Institute (Manchester).The next day the data loggers were collected and the data downloaded to a computer. They were analysed for technical problems such as loss of probes and only unblemished data were analysed further. For each night of recording rectal temperature was abstracted at 30 minute intervals from one hour before bedtime until nine hours later. ResultsTwenty six of the 30 subjects yielded sufficient data to be certain of the individual pattern of development, a total of 246 nights of recording. For the remaining four infants data were not available for one or more weeks around the critical age for a variety of reasons. The mean (SD) gestational age of the 26 infants was 39-9 (1 -5) weeks, with all but one born between 38 and 42 weeks and none before 36 weeks. The birth weight averaged 3471 (485) g and 13 were boys. The average maternal age was 27-3 (4-6) years. Six of the infants had parents in occupational groups 1 or 2, and seven in groups 4 or 5, a social class distribution similar to that of the Leicestershire population as a whole. Nine were first children; three had two or more older ...

Evaluation of the thermal insulation of clothing of infants sleeping outdoors in Northern winter

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