Objectives To determine the effects on weight gain and temperature control of transferring preterm infants from incubators to open cots at a weight of 1600 g versus a weight of 1800 g.

Design Randomised controlled trial.

Setting One tertiary and two regional neonatal units in public hospitals in Queensland, Australia.

Participants 182 preterm infants born with a birth weight less than 1600 g, who were at least 48 h old; had not required ventilation or continuous positive airways pressure within the last 48 h; were medically stable with no oxygen requirement, or significant apnoea or bradycardia; did not require phototherapy; and were enterally fed with an intake (breast milk/formula) of at least 60 ml/kg/day.

Interventions Transfer into an open cot at 1600 or 1800 g.

Main outcome measures The primary outcomes were temperature stability and average daily weight gain over the first 14 days following transfer to an open cot.

Results 90 infants in the 1600 g group and 92 infants in the 1800 g group were included in the analysis. Over the first 72 h, more infants in the 1800 g group had temperatures <36.4°C than the 1600 g group (p=0.03). From post-transfer to discharge, the 1600 g group had more temperatures >37.1°C (p=0.02). Average daily weight gain in the 1600 g group was 17.07 (SD±4.5) g/kg/day and in the 1800 g group, 13.97 (SD±4.7) g/kg/day (p=<0.001).

Conclusions Medically stable, preterm infants can be transferred to open cots at a birth weight of 1600 g without any significant adverse effects on temperature stability or weight gain.

Trial registration: ACTRN12606000518561 (http://www.anzctr.org.au).