Background: Neonatal hypothermia remains a common problem and is related to elevated morbidities and mortality. However, the long-term neurodevelopmental effects of admission hypothermia are still unknown. This study attempted to determine the short-term and long-term consequences of admission hypothermia in VLBW preterm infants.
Study design: This retrospective study measured the incidence and compared the outcomes of admission hypothermia in very low birth weight (VLBW) preterm infants in a tertiary-level neonatal intensive care unit. Infants were divided into the following groups: normothermia (36.5-37.5°C), mild hypothermia (36.0-36.4°C), moderate hypothermia (32.0-35.9°C), and severe hypothermia (< 32°C). We compared the distribution, demographic variables, short-term outcomes, and neurodevelopmental outcomes at 24 months of corrected age among groups.
Results: We studied 341 infants: 79 with normothermia, 100 with mild hypothermia, 162 with moderate hypothermia, and 0 with severe hypothermia. Patients in the moderate hypothermia group had significantly lower gestational ages (28.1 wk vs. 29.7 wk, P < .02) and smaller birth weight (1004 g vs. 1187 g, P < .001) compared to patients in the normothermia group. Compared to normothermic infants, moderately hypothermic infants had significantly higher incidences of 1-min Apgar score < 7 (63.6% vs. 31.6%, P < .001), respiratory distress syndrome (RDS) (58.0% vs. 39.2%, P = .006), and mortality (18.5% vs. 5.1%, P = .005). Moderate hypothermia did not affect neurodevelopmental outcomes at 2 years' corrected age. Mild hypothermia had no effect on short-term or long-term outcomes.
Conclusions: Admission hypothermia was common in VLBW infants and correlated inversely with birth weight and gestational age. Although moderate hypothermia was associated with higher RDS and mortality rates, it may play a limited role among multifactorial causes of neurodevelopmental impairment.