Accuracy of infrared thermometers in very low birth weight infants and impact on newborn behavioural states


  • Conflict of interest: The authors declare no conflict of interest.

Correspondence: Ms Melanie Jarvis, Department of Paediatrics, Mercy Hospital for Women, 163 Studley Road, Melbourne, Vic. 3084, Australia. Fax: 03 9459 5389; email:;



To study the impact on newborn behavioural states and accuracy of three infrared thermometers compared with digital axillary thermometer measurements in very low birth weight infants.


Single-centre prospective observational study. Preterm infants born <1500-g birth weight were eligible. Infants were observed for pre-measurement behaviour state using a five-point neonatal behaviour observation tool. One infrared temperature was taken from each of the devices, followed by an axillary measurement. Further behaviour-state observations were recorded following infrared and axillary measurements.


One hundred measurements were collected from each infrared device among a cohort of 42 very low birth weight infants. Only one infrared device showed satisfactory agreement with bias −0.071 (95% limits of agreement −0.68 to 0.54). The other two devices demonstrated poor agreement: bias −1.34; 95% limits of agreement −2.62 to –0.5 and bias −0.56; 95% limits of agreement −1.38 to 0.25. Neonatal behavioural scores showed only minimal changes when infrared measurements were performed but increased significantly following axillary measurements. The difference between the two modalities was statistically significant with a mean increase of 1.44 points following axillary measurements (95% confidence interval 1.21 to 1.67, P < 0.001).


Temperature measurements taken with infrared thermometers demonstrated less disruption to preterm infants' behavioural state, however accuracy of devices varied.