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 between neonatal units. This preferred weight mark 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 June 2003 back to 1966, CINAHL from June 2003 back to 1987 and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2003). 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 randomly 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.

Four studies were identified as potentially eligible for inclusion in this review. Two studies were excluded as random allocation to the exposure was not employed. One study is pending, awaiting additional information from the authors. Therefore, one study involving 60 preterm infants, employing a matched-pairs design, which compared the transfer of infants to open cots at 1700 g versus 1800 g, is included in this review. Only two outcomes could be included from this study; return to incubator and daily weight gain. No statistically significant difference was shown for either return to incubator (RR 2.00, 95% CI 0.40 to 10.11) or daily weight gain [MD 4.00 g/day (95% CI -5.23, 13.23)]. Due to small numbers, 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.