What are the recommended thermoregulation strategies for premature infants, including incubator temperature and humidity settings, use of polyethylene wraps, skin‑to‑skin care, and temperature monitoring?

Thermoregulation for Premature Infants

Core Temperature Management Strategy

For preterm infants <32 weeks' gestation, use a combination of interventions including environmental temperature 23-25°C, plastic wrapping without drying, cap, and thermal mattress to prevent hypothermia on NICU admission. 1

Delivery Room Interventions

Immediate interventions for infants <32 weeks' gestation:

• Apply polyethylene wrap or bag immediately after birth without drying the infant - this significantly reduces hypothermia risk (reduces hypothermia incidence by 25%, with NNTB of 4-5) and improves admission temperature by 0.58°C compared to routine care 2

• Place a skullcap on the infant's head to minimize heat loss from the large surface area of the head 3

• Use a thermal (exothermic) mattress - this keeps infants ≤1500 grams significantly warmer (0.65°C higher temperature) and reduces hypothermia incidence 2, 4

• Maintain delivery room temperature at 23-25°C 1

• Obtain axillary temperature at 10 minutes after birth for early detection of thermal instability 4

Target Temperature Parameters

Maintain core body temperature at 37.0°C as the target 3

Define hypothermia as <36.0°C and avoid hyperthermia >38.0°C 1

• Hypothermia on admission remains strongly predictive of adverse outcomes across all gestations 2
• When using multiple warming interventions simultaneously, monitor carefully for iatrogenic hyperthermia, as risk increases 3.91-fold with plastic wraps 2
• Fewer infants fall outside the normothermic range when plastic wraps are used (20% reduction, NNTB of 5) 2

Rewarming Hypothermic Infants

If an infant presents with unintentional hypothermia after birth, initiate rewarming using a protocol with frequent or continuous temperature monitoring, but current evidence is insufficient to recommend either rapid (≥0.5°C/hour) or slow (<0.5°C/hour) rewarming rates. 1

Critical rewarming considerations:

• Use servo-controlled devices when available for monitoring and controlling rewarming rate 1
• Avoid supraphysiological set temperature points due to hyperthermia risk - one study found 12.5% of infants developed hyperthermia during rapid rewarming 1
• Monitor blood glucose during rewarming as hypothermic infants have increased hypoglycemia risk 1
• The safe maximum rate of rewarming has not been established 1

Skin-to-Skin Care (SSC)

Immediate skin-to-skin contact is effective for thermoregulation and should be implemented even in very preterm infants in high-resource settings:

• SSC reduces hypothermia risk by 91% (RR 0.09) for infants 1200-2199 grams compared to incubator care 2
• Very preterm infants (28-32 weeks) maintain stable temperatures during immediate SSC after birth, with mean temperatures only 0.2°C lower than conventional care but 30% lower risk of hyperthermia 5
• Novel approaches like the Skincubator reduce temperature drop to 0.2°C versus 0.4°C with traditional SSC, decrease hypothermia time from 27.8 to 8.2 minutes per session, and maintain 85% humidity 6

Incubator Management

For preterm infants <1600 grams, use closed convective incubators with humidified environment: 3

• No clear superiority exists between single-wall versus double-wall incubators 3
• No definitive advantage for air versus skin servo control mode 3
• Humidify and warm inhaled gases to limit insensible water loss 3
• Maintain humidity >70% when possible, particularly for extremely preterm infants 6

Implementation Bundle

A multidisciplinary guideline approach significantly reduces hypothermia rates:

• Implementation of standardized protocols reduced hypothermia (<36.5°C) from 63% to 30% and moderate hypothermia (<36°C) from 29% to 9% 4
• Key bundle elements: increased operating room temperature, 10-minute temperature measurement, exothermic mattress for all <35 weeks, polyethylene wrap for <32 weeks 4

Critical Pitfalls to Avoid

• Do not use plastic wraps alone for extremely preterm infants - combine with thermal mattress and other interventions 1, 2
• Do not delay temperature assessment - obtain measurement within 10 minutes of birth 4
• Do not assume SSC causes hypothermia - concerns about thermal regulation should not limit SSC implementation in high-resource settings 5
• Do not use multiple warming interventions without continuous monitoring - hyperthermia risk increases significantly 2