Background Serial accurate length measurements of preterm babies give invaluable information on growth. Until recently there has been a lack of equipment to carry this out. Previous methods have been inaccurate or cumbersome. In 2010 the leicester incubator measure (LIM) was developed and the authors carried out an evaluation of its ease of use and its impact on babies physiological state.

Method Two observers devised an observation proforma and carried out single length measurements in a group of 22 babies being nursed on special care. For the last 13 babies additional information was gathered on sleep/wake state and vocalisation.

Results Babies ranged from 24+1 to 32+5 weeks at birth with average of 27+6.

At time of measurement they ranged from 28+0 to 38+1 weeks with average of 30+6.

Of full cohort 12 in incubator, 10 in cot, with 13 in air, 4 cycling off CPAP and 3 in nasal prong oxygen. Average time to complete length 4 min 20 s (range 3–9 min). No baby had any bradycardia or apnoea. For the last 13 babies 5 were awake prior to procedure 5 woke during it and 3 remained in sleep like state. Six went back to sleep taking an average of 30 s. 6 of the 13 cried with an average of 43 s to completely settle (range 15–60 s)

Discussion The LIM create minimal disturbance in this group of preterm babies, further work is needed to evaluate feasibility of serial measurements to assess and monitor growth.