Evidence
Alert

Plastic wraps or bags keep pre-term infants warm immediately after birth

Cheap and simple plastic wrapping used in the first 10 minutes after birth helps pre-term and low birth weight infants avoid hypothermia. Infants treated in this way are likely to be warmer when admitted to neonatal intensive care than those treated according to standard care. Pre-term infants are most likely to benefit.

Routine infant care usually involves ensuring the delivery room is warm, drying the infant immediately after birth, wrapping the infant in pre-warmed dry blankets and pre-warming surfaces. Despite this, about a quarter of babies born eight weeks early have temperatures that are too low and additional measures to warm pre-term and low birth weight infants are needed.

Although babies were warmer after the intervention, this review of 19 published studies did not show that these interventions improved survival, or reduced the chances of short or long-term conditions associated with cold, perhaps because of the size of the trials.

 

Why was this study needed?

Hypothermia immediately after birth remains a worldwide problem, in both resource-rich and poorer countries. The UK National Neonatal Audit Programme highlighted hypothermia as a concern, after it found 25% of infants born at less than 32 weeks gestation in this country had a recorded temperature below the recommended range in 2016. Newborn babies, particularly pre-term infants, rely on external help to maintain their temperature, particularly in the first 12 hours of life. Maintaining a near normal temperature is important for survival and is a worldwide issue across all climates because of the link to a variety of complications including brain injury and bleeding into the lung.

Optimum interventions have so far been unclear, partly because of lack of consistency in measuring infants’ temperatures.

This study assessed efficacy and safety of interventions designed for preventing hypothermia in preterm or low birth weight infants, used within 10 minutes of birth. The main comparison was between plastic wraps or bags to reduce heat loss, versus routine care. The study also looked at external heat sources, including skin-to-skin care and heated mattresses.

 

What did this study do?

This systematic review included 25 randomised or quasi-randomised trials, with a total of 2,433 infants. Fourteen studies were conducted in high-income countries, seven studies in upper-middle income countries and four in lower-middle income countries. Two studies were from the UK. The main outcome was the temperature of the infant on admission to the neonatal intensive care unit (NICU) or up to two hours after birth.

Studies were included if they involved preterm infants of less than 37 weeks’ gestation, and/or weighing 2,500 grams or less. Interventions to prevent hypothermia were applied within 10 minutes of birth. Infants with major birth defects were not included. The strength of evidence for the main comparison was judged as moderate.

 

What did it find?

  • Plastic wraps improved babies’ core body temperature on admission to the NICU, or up to two hours after birth (mean difference [MD] 0.58°C, 95% CI 0.50-0.66), based on 13 studies with 1,633 participants.
  • Fewer wrapped infants, 495 per 1,000, had hypothermia, on admission to the NICU, or up to two hours after birth, compared to 738 per 1,000 in the usual care group (RR 0.67, 95% CI 0.62 to 0.72). This result was based on 10 studies with 1,417 participants. Hypothermia was defined as core body temperature less than 36.5°C or skin temperature less than 36°C.
  • However, the practice did increase the risk of overheating. The risk of hyperthermia on admission to NICU or up to two hours after birth increased from 12 per 1,000 in the usual care group to 46 per 1,000 in the wrapped group (RR 3.91, 95% CI 2.05 to 7.44). This result was based on 12 studies including 1,523 participants
  • There was insufficient evidence to show that plastic wraps or bags significantly reduced the risk of death during hospital stay. Mortality was 153 per 1,000 for wrapped preterm babies and 168 per 1,000 for usual care preterm babies (RR 0.91, 95% CI 0.73 to 1.15).
  • There was some evidence that skin-to-skin care (one study) and heated mattresses (two studies) reduced the risk of hypothermia. However, only 157 participants were included in these external heat source studies.

 

What does current guidance say on this issue?

The Royal College of Midwives recommends keeping the baby warm at birth using skin-to-skin contact between mother and baby, and drying with pre-warmed towels. If the mother is unable to hold the baby immediately, they should be wrapped in warmed towels and placed under a radiant warmer.

In 2015, the World Health Organisation said there was “insufficient evidence” on the use of plastic bags or wraps in providing thermal care for pre-term newborn infants, but that the practice “may be considered” when transferring babies to NICUs.

 

What are the implications?

Reducing morbidity and mortality in premature babies remains a challenge in the UK and globally. Based on this study, midwives and obstetricians can be advised that plastic wrapping is a cheap, simple and effective way to maintain body temperature, especially for very preterm infants. It may also improve clinical outcomes, too.

Clinicians using plastic wraps and heated mattresses must take care to avoid hyperthermia, especially when the interventions are used together.

Future studies could include more participants, standardise outcomes and lengthen follow up to better understand the long-term effects of these interventions.

 

Citation and Funding

McCall EM, Alderdice F, Halliday HL, et al. Intervention to prevent hypothermia at birth in preterm and/or low birth weight infants. Cochrane Database Syst Rev. 2018;2:CD004210.

This study received funding support from Northern Ireland Neonatal Intensive Care Outcomes Research and Evaluation Group (NICORE), and the Research & Development Office, Northern Ireland.

 

Bibliography

NHS Choices. Hypothermia. London: Department of Health; updated 2017.

NICE. Surgical site infection. QS49. London: NICE; 2013.

RCPCH. 2017 National Neonatal Audit Programme annual report on 2016 data. London: Royal College of Paediatrics and Child Health; 2017.

The Royal College of Midwives. Evidence based guidelines for midwifery-care in labour. London: The Royal College of Midwives; 2012.

WHO. Infants: reducing mortality. Geneva: The World Health Organization; 2017.

WHO. WHO recommendations on interventions to improve preterm birth outcomes. Geneva: The World Health Organization; 2015.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre

 

Hypothermia is a dangerous drop in body temperature below 35°C. Normal temperature being around 37°C. Hypothermia can be serious if not treated quickly. Babies with hypothermia may look healthy, but their skin will feel cold. They may also be limp, usually quiet and refuse to feed (NHS 2017).

Commentaries

Expert commentary

At birth, preterm infants are at high risk of becoming cold quickly. Cold can cause harm or even death in this group of babies.

Trials show that interventions such as plastic wrapping or heaters can prevent hypothermia; however, few investigate the same intervention, and so it is not clear which type is best in which situation.

It is time to stop conducting small trials that only assess infant temperature and conduct trials that are large enough to evaluate the benefits and risks of providing these interventions on important health outcomes.

Dr Diane Farrar, NIHR Post-doctoral Research Fellow & Maternal Health Research Programme Manager, Bradford Institute for Health Research, Bradford Teaching Hospitals