Transfer of preterm infants from incubator to open cot at lower versus higher body weight

The use of incubators in helping to maintain a thermoneutral environment for preterm infants has become routine practice in neonatal nurseries. As one of the key criteria for discharging preterm infants from nurseries is their ability to maintain temperature; the infant will need to make the transition from incubator to open cot at some time before discharge. The timing of this transition is important because, when an infant is challenged by cold, the infant attempts to increase its heat production to maintain body temperature. The increase in energy expenditure may affect weight gain. The practice of transferring infants from incubators to open cots usually occurs once a weight of around 1700 - 1800 g has been reached; however, this practice varies widely among neonatal units. This target weight appears to be largely based on tradition or the personal experience of clinicians, with little consideration of the infant's weight or gestational age at birth.

The main objective was to assess the effects on weight gain and temperature control of a policy of transferring preterm infants from incubator to open cot at lower versus higher body weight.

Searches were undertaken of MEDLINE from April 2007 back to 1950, CINAHL from April 2007 back to 1982 and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007). The title and abstract of each retrieved study were examined to assess eligibility. If there was uncertainty, the full paper was examined.

Trials in which preterm infants were allocated to a policy of transfer from incubators to open cots at a lower body weight versus at a higher body weight.

Quality assessments and data extraction for included trials were conducted independently by the reviewers. Data for individual trial results were analysed using relative risk (RR) and mean difference (MD). Results are presented with 95% confidence intervals (CI). Due to insufficient data, meta-analysis could not be undertaken.

Five studies were identified as potentially eligible for inclusion in this review. Three studies were excluded as neither random nor quasi-random allocation to the exposure was employed. Two small quasi-randomised studies, involving 74 preterm infants are included in this review. These studies compared the transfer of infants to open cots at 1600 - 1700 g vs. 1800- 1900 g, and 1700 g vs. 1800 g. Data for only two prespecified outcomes could be included in this review. No statistically significant difference was shown for either return to incubator [one trial (N = 60) RR 2.00; 95% CI 0.40 to 10.11] or daily weight gain measured in g/kg/day [one trial (N = 14) MD 1.00 g/kg/day; 95% CI -2.89, 4.89]. Due to insufficient data, meta-analysis was not performed and effects on clinically important outcomes could not be adequately assessed.

There is currently little evidence from randomised trials to inform practice on the preferred weight for transferring preterm infants from incubators to open cots. There is a need for larger randomised controlled trials to address this deficiency.