Overview

Newborns lose heat through four mechanisms — evaporation, conduction, convection, and radiation — and cannot shiver. Instead they burn brown fat via nonshivering thermogenesis, which consumes glucose and oxygen and directly links cold stress to hypoglycemia and metabolic acidosis. The goal is a neutral thermal environment (NTE), where oxygen consumption and metabolic demand are minimized. Normal axillary temperature is 36.5–37.5 °C (97.7–99.5 °F); cold stress begins below 36.5 °C. Preterm and small-for-gestational-age newborns are highest risk (less brown fat, more body surface area per kilogram).

Interpretation

Evaporation → dry thoroughly Hallmark

Wet skin after delivery; greatest heat loss at birth — dry first before any other warming

Conduction → skin-to-skin

Heat lost to cold surfaces by contact; warm parent's chest or prewarmed blanket/surface

Convection → reduce air currents

Air moving over exposed skin (fans, drafts, open windows); raise room temp, avoid drafts

Radiation → move from cold surfaces

Heat to nearby cold walls/windows without contact; move bassinet away from exterior window

Knit cap on head

Head is large surface area (~25% BSA); reduces radiant and convective loss

Normal axillary temp 36.5–37.5 °Caxillary temp 36.5–37.5 °C (97.7–99.5 °F)

Cold stress begins below 36.5 °C

Technique

Dry thoroughly, remove wet linens Hallmark

Eliminates evaporative loss — the single greatest source at birth

Place knit cap on head

Covers the largest proportional heat-loss surface

Initiate skin-to-skin on parent's chest

Conductive warmth; gold standard for well newborns. Radiant warmer for at-risk/resuscitation

Monitor axillary temp serially until stable

Confirms interventions are working; commonly q30 min until stable, then per protocol

Delay first bath until temperature stable

Bathing accelerates evaporative/convective loss and removes vernix

During — Monitoring

Monitor

Axillary temperature

Serial checks confirm rewarming; goal 36.5–37.5 °C

Blood glucose

Nonshivering thermogenesis depletes glucose — cold stress drives hypoglycemia

Respiratory rate and effort

Tachypnea/distress signals the cold-stress metabolic cascade

Avoid overly rapid rewarming

Rapid rewarming is associated with apnea

Patient Teaching

Keep newborn dry and capped

Re-cover after every diaper change or weigh

Skin-to-skin contact

Maintains temperature and supports bonding/feeding

Delay first bath

Until temperature has been stable; preserves vernix and warmth

Avoid drafts and cold surfaces

No fans/open windows over the newborn; keep away from exterior windows

Report Nowescalate immediately

Cold stress, temp below 36.5 °C Hallmarkaxillary temp < 36.5 °C

Triggers increased O2 consumption, metabolic acidosis, and respiratory distress if uncorrected

Temperature instability despite rewarming

Cold stress corrects with rewarming; instability that worsens or persists suggests sepsis — escalate

Respiratory distress or tachypnea

Sign of the cold-stress cascade (metabolic acidosis → pulmonary vasoconstriction)

Jitteriness or lethargy with poor feeding

Suggests hypoglycemia from glucose depletion; check glucose

Metabolic acidosis on ABG

Low pH with base deficit reflects lactic acid from brown-fat thermogenesis

Clinical Pearl

Dry, hat, skin-to-skin — in that order. Every second a wet newborn stays uncovered is a calorie burned and a glucose point lost.

Newborn Thermoregulation

Overview

Interpretation

Technique

During — Monitoring

Patient Teaching

A healthy full-term newborn can lose enough heat in the first minutes of life to trigger a metabolic crisis — not from illness, but from physics the nurse failed to interrupt.

Key Distinctions

Clinical Pearl

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