Review question: What is known about the efficacy and safety of interventions designed to prevent hypothermia in preterm and/or low birth weight babies applied within 10 minutes after birth in the delivery room, compared with routine thermal care or any other single/combination of intervention(s)?

Background: Preventing low body temperature at birth in preterm and low birth weight babies may be important for survival and long-term outcomes. Babies rely on external help to maintain temperature, particularly in the first 12 hours of life. For vulnerable babies born preterm or at low birth weight, abnormally low body temperature (hypothermia) is a worldwide issue across all climates and has been linked to a variety of complications including death. Preventive action is taken by reducing heat loss and/or providing warmth through external heat sources. Precautionary steps routinely include ensuring a warm delivery room; drying immediately after birth, especially the head; wrapping in prewarmed dry blankets (including the head); prewarming surfaces; and eliminating draughts.

Search date: We used the standard search strategy of the Cochrane Neonatal Review Group to search CENTRAL (2016, Issue 5), MEDLINE (1966 to 30 June 2016), Embase (1980 to 30 June 2016), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 30 June 2016). We also searched clinical trials databases, conference proceedings, and reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

Key results: This review identified 25 studies involving 2433 babies; researchers used additional preventive actions in the first 10 minutes of life to prevent problems with hypothermia. Use of plastic coverings, heated mattresses, and skin-to-skin contact kept infants warmer (and within normal body temperature ranges) than routine preventive action. However, care must be taken, particularly when these methods are combined, to avoid the unintended effect of making babies too warm, which may be harmful. Limitations consist of small numbers of babies and studies included in some comparison groups; variations in methods and definitions used for normal body temperature and routine care; and differences in materials used.

Although this review confirmed that some of these measures are effective in preventing hypothermia, results across all studies show no reduction in deaths and only limited improvement in short-term complications or illnesses normally associated with being too cold. Findings suggest that perhaps hypothermia is a marker for poorer outcomes, particularly in the most immature and smallest babies, rather than a direct cause. Review authors recommend that future studies should be large enough to detect changes for rarer illnesses, should define these illnesses in the same way so they can be combined across studies, and should focus on longer-term consequences.

Quality of the evidence: Overall for the main comparison group (plastic wraps or bags vs routine care), we are moderately confident that trial results and our conclusions are reliable. Across the remaining comparison groups, evidence is insufficient to allow firm judgements mainly because numbers of studies and sample sizes are small.

In comparisons of plastic wraps or bags versus routine care to keep preterm or low birth weight babies warm, we rated the quality of evidence as moderate for key outcomes. Across outcomes reporting on babies' regulation of their body temperature, we suspect that some small trials showing that the intervention did not keep these babies warmer may not have been published, findings of studies were not in agreement, or evidence was based on small numbers of studies or events. For major complications of brain injury and bleeding into the lung (pulmonary haemorrhage), the number of events was too small or findings were based on only one study. We suspect that some small trials reporting deaths may not have been published; however this was unlikely to have affected review findings.