Introduction
Neonatal hypothermia has long been recognised as a risk factor for mortality and morbidity in preterm infants. Recent studies confirm that lower admission temperatures correlate with increased risks of mortality and conditions such as intraventricular hemorrhage (IVH), respiratory distress syndrome, and necrotizing enterocolitis (NEC). A new study, based on data from the Norwegian Neonatal Network (NNN), examined admission temperatures of infants born before 32 weeks of gestation in Norway over a ten-year period. The research explored trends, hospital practices, and the relationship between hypothermia and health outcomes.
Study Design and Methods
This population-based study analyzed data from all 20 neonatal intensive care units (NICUs) in Norway. It included 4,879 infants born at less than 32 weeks gestational age (GA) who were admitted to neonatal care within two hours of birth between 2012 and 2021. Exclusions were applied to infants who were outborn, had major congenital anomalies, or lacked temperature data.
A survey was conducted to assess hospital practices regarding temperature preservation during delivery room (DR) management and transport to the NICU. Data were analyzed to determine trends in admission temperature and its association with neonatal mortality and morbidity.
Key Findings
- The average admission temperature was 36.5°C, ranging from 32.2°C to 39.5°C.
- 50.4% of infants had normal temperatures (36.5°C–37.5°C), while 26.9% had mild hypothermia (36.0°C–36.4°C) and 18.2% had moderate to severe hypothermia (<36.0°C).
- The occurrence of moderate to severe hypothermia varied significantly among hospitals, ranging from 7% to 40% for infants ≥28 weeks GA and 11% to 30% for infants <28 weeks GA, likely due to differences in protocols, training, and resources.
- The rate of hypothermia declined over time, from 54% in 2012 to 36% in 2021, reflecting improvements in neonatal care.
- Infants with moderate to severe hypothermia had significantly lower birth weights and gestational ages, higher illness severity scores, and lower Apgar scores at 5 minutes.
Impact on Mortality and Morbidity
- Overall, 7.8% of the infants in the study died before hospital discharge.
- Severe hypothermia (<34.0°C) was associated with a 2.35-fold increase in mortality compared to normothermic infants, while moderate hypothermia (34.0°C–35.9°C) was linked to a 1.5-fold increase.
- The association between hypothermia and mortality was strongest in the first 24 hours after birth.
- Hypothermia was independently linked to a higher risk of surgery for NEC or spontaneous intestinal perforation (SIP), but no significant associations were found with severe IVH, retinopathy of prematurity (ROP), or bronchopulmonary dysplasia (BPD). While the study suggests a strong correlation, further research is needed to confirm causation.
Hospital Practices and Recommendations
- Hospitals with routine temperature measurement before transport to NICU had significantly lower hypothermia rates.
- No single intervention (e.g., plastic wraps, higher room temperatures, radiant warmers) was found to be solely responsible for improved thermal management.
- Continuous temperature monitoring before NICU admission may further improve outcomes.
Conclusion
This study highlights the importance of maintaining normothermia in preterm infants and demonstrates a clear association between lower admission temperatures and increased mortality. While progress has been made in reducing neonatal hypothermia over the past decade, variation in hospital practices suggests room for further improvement. Implementing standardized temperature-preserving measures and continuous monitoring could enhance neonatal care and reduce risks for vulnerable preterm infants.
SurePulse
The results from this new publication are of particular importance to SurePulse, whose vision is a world where baby-centred innovation transforms neonatal outcomes. SurePulse is currently conducting clinical investigations of their new multi-parameter device, designed to monitor temperature continuously (amongst other vital signs) in the first minutes and hours after birth.
Researchers at Nottingham University Hospital presented a poster about the initial temperature findings at EAPS 2024, concluding that “the novel multiparameter sensor is effective for rapid and accurate temperature monitoring in newborns under varying conditions, outperforming traditional methods. Its ability to provide wireless and continuous temperature readings may enhance thermal management during newborn stabilisation in delivery rooms and operating theatres.”
See the full poster presentation here to explore the detailed findings.
References
