Interventions to prevent hypothermia at birth in preterm and/or low-birth-weight infants

Plastic wraps or bags, plastic caps, skin-to-skin contact and the transwarmer mattress are effective interventions for preventing hypothermia in preterm and/or low-birth-weight infants, although polyethylene bags have been reported to cause hyperthermia in infants. To implement community-based hypothermia prevention approaches involving behaviour change and home visits, an integrated package of preventive and curative newborn care and social networks that target multiple levels of community stakeholders should be developed and utilized.

RHL Commentary Wariki WMV and Mori R

1. INTRODUCTION

In under-resourced settings in low- and middle-income countries, hypothermia at birth is one of the most important risk factors for morbidity and mortality in newborn infants of all birth weights and gestational ages. It is estimated 99% of the 4 million babies that die each year worldwide during the neonatal period (0-27 days) live in those settings (1);. for example, complications of preterm birth are a leading cause of mortality (54%) in southeast Asia (2). Furthermore, 47% of all mothers and newborns in developing countries do not receive skilled care during childbirth, and 72% of all babies born outside health-care facilities do not receive any postnatal care (1). Evidence shows that the first days of life are critical as most neonatal deaths occur during this period (25%–45% within the first 24 hours) (1). These statistics represent the critical gaps in the continuum of care due to a backdrop of poverty, suboptimum care-seeking, and weak health systems (1, 3). Additionally, a baby born with a low birth weight, particularly if the baby is also preterm, is at much greater risk of dying or getting sick than other newborns.

Prevention and management of hypothermia is one of the key interventions for reducing neonatal mortality and morbidity. According to UNICEF, such interventions can help reduce neonatal mortality or morbidity by 18%–42% (4). The objective of this Cochrane review (5) was to assess efficacy and safety of interventions designed to prevent hypothermia in preterm and/or low-birth-weight infants applied within the first 10 minutes after birth in the delivery ward compared with routine thermal care.

2. METHODS OF THE REVIEW

Infants with major congenital malformations, particularly abdominal wall defects, were excluded. "Routine thermal care" included: the delivery room temperature at a minimum of 25º C; drying of the infant immediately after birth; removing any wet blankets and wrapping the infant in a pre-warmed blanket; pre-warming any contact surfaces; avoiding draughts; and use of radiant warmers or incubators. The definitions of hypothermia were inconsistent across the studies.

The search and analysis strategies for conducting this systematic review were appropriate and assessed by at least three review authors independently. The authors sought trials that had employed randomized or quasi-randomized allocation methods to test a specific intervention designed to prevent hypothermia immediately after birth.

All of the trials included in the meta-analysis and have been analysed appropriately using the fixed-effect model. The authors mentioned that they carried out a planned subgroup analysis for gestational age and birth-weight.

The primary outcome of interest was core body temperature (axillary) of the infants taken on admission to the neonatal intensive care unit or up to two hours after birth, and secondary outcomes were categorized as morbidity and adverse outcomes due to the intervention.

3. RESULTS OF THE REVIEW

Overall, 160 studies were identified, but only seven randomized controlled trials involving 400 randomized infants fulfilled the inclusion criteria (391 infants actually completed the studies). The available studies were divided into two categories of intervention: (i) five studies had compared barriers to heat loss (three studies involved plastic wraps or bags, one study had used plastic caps, and one study had used Stockinette caps) with routine thermal care and involved 143 (intervention group) versus 193 (control) infants, respectively; and (ii) two studies had compared external heat sources (one had used skin-to-skin contact and the other a transwarmer mattress) with routine care (30 versus 25 infants, respectively). Participants were categorized by gestational age (all preterm) in five studies, and by birth weight (all low-birth-weight infants) in two studies.

Meta-analysis of the four studies found that plastic wraps (polyurethane or polyethylene bag) were statistically significantly more effective than routine care in reducing heat losses in infants aged < 28 weeks’ of gestation [weighted mean difference (WMD) 0.68oC; 95% confidence interval (CI) 0.45–0.91], but there was no difference in the risk of death during hospital stay. Compared with routine care, skin-to-skin care was effective in reducing the risk of hypothermia in infants weighing between 1200 and 2199 grams [relative risk (RR) 0.09; 95% CI 0.01–0.64]. The transwarmer mattress kept infants weighing ≤1500 grams significantly warmer than routine care and reduced the incidence of hypothermia on admission to neonatal intensive care unit. Stockinette caps were not effective in reducing heat loss in infants. There was limited reporting of pre-specified secondary outcomes throughout the studies. Hyperthermia (defined as an admission temperature to a neonatal intensive care unit or within two hours of birth of >37.5º C) was reported as the most frequent adverse effect from two trials that had used wraps or bags in the delivery room.

4. DISCUSSION

4.1 Applicability of the results

This review provides new evidence that plastic wraps, plastic caps, skin-to-skin contact and the transwarmer mattress are effective interventions for preventing hypothermia in preterm and/or low-birth-weight infants. In contrast, polyethylene bags have also been reported to cause hyperthermia in infants (6).

It is difficult to extrapolate the results of this review to low- and middle income countries because only one of the six trials in the review had been conducted in such a setting (a skin-to-skin contact study from South Africa). In low-income settings, factors such as cultural beliefs surrounding childcare and accessibility of health care can be potential barriers to effectiveness of such interventions. Moreover, only one of the included studies with a small numbers of infants was conducted in parts of the world that have the highest rates of neonatal mortality (sub-Saharan Africa and Asia) (2).

4.2 Implementation of the interventions

In the trial from South Africa, compared with conventional incubator care, skin-to-skin care was shown to be effective in reducing the risk of hypothermia in infants with a birth weight of between 1200 grams and 2199 grams. In under-resourced settings, skin-to-skin contact between the baby and the person taking care of the baby (mostly the mother or a relative) is a feasible, low-cost intervention that can be implemented both at a health-care facility and at home. In general, in health-care facilities in under-resourced settings, health-care professionals need to improve their routine practices to minimize the risk of cold stress for newborn infants immediately after birth.

Randomized controlled trials conducted in South Asia suggest that community-based newborn-care interventions are effective in reducing neonatal mortality in high neonatal mortality settings with weak health systems and low use of available health-care facilities (7, 8, 9). A trial in India assessed the management of hypothermia (including, among others, skin-to-skin contact for thermal protection) using behaviour-change approaches such as group meetings and home visits. This study found that home visits help families in not only identifying newborn problems early but also in overcoming constraints to care-seeking from appropriate providers (7). Home visits have also been shown to be useful in promoting practices designed to keep the baby warm. In order to implement community-based approaches involving behaviour change and home visits, an integrated package of preventive and curative newborn care and social networks that target multiple levels of community stakeholders should be developed and utilized.

4.3 Implications for research

There is a need to carry out large high-quality randomized controlled trials, particularly in low- and middle-income countries, to study specific feasible interventions for the thermal protection of preterm or low-birth-weight infants. Community-based interventions would be more appropriate than facility-based ones, since most of the neonatal mortality in under-resourced settings occurs at home due to poor access to health care (10). In developing interventions, consideration should be given to cost–effective interventions, especially in low-income countries, where cost is a important concern. Potential cultural barriers and proportion of infants protected by the interventions should also be studied.

Sources of support: None

References

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  • WHO/UNICEF joint statement. Home visits for the newborn child: a strategy to improve survival. Geneva: World health Organization; 2009.

This document should be cited as: Wariki WMV and Mori R. Interventions to prevent hypothermia at birth in preterm and/or low-birth-weight infants: RHL commentary (last revised: 1 June 2010). The WHO Reproductive Health Library; Geneva: World Health Organization.

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