Association of Moderate Hypothermia at Admission with Short-Term and Long-Term Outcomes in Extremely Low Birth Weight Infants

Abstract

Purpose: Extremely low birth weight (ELBW) infants exhibit immature thermoregulation and are easily exposed to hypothermia. We investigated the association between hypothermia on admission with short- and long-term outcomes.Methods: Medical records of ELBW infants admitted to the neonatal intensive care unit of a tertiary medical center between June 2012 and February 2017 were retrospectively analyzed. Upon admission, the axillary body temperature was measured. Moderate hypothermia was defined as admission temperature below 36 ℃.Results: A total of 208 infants with gestational age of 26.4±2.3 weeks and birth weight of 746.7±154.9 g were included. Admission temperature ranged from 33.5 to 36.8 ℃ (median 36.1 ℃). Univariate analyses of maternal and infant characteristics were performed for moderately hypothermic and control (normothermic to mildly hypothermic) infants. Lower gestational age, lower birth weight, and vaginal delivery correlated with moderate hypothermia. Logistic regression analyses adjusted for confounders revealed that the incidence of hemodynamically significant patent ductus arteriosus (hsPDA) was associated with moderate hypothermia in ELBW infants. Moreover, abnormal mental developmental index scores on the Bayley Scales of Infant Development II at a corrected age of 18 to 24 months were associated with moderate hypothermia, but not with the psychomotor developmental index, incidence of blindness, deafness, or cerebral palsy.Conclusion: Moderate hypothermia at admission is not only correlated with short-term neonatal morbidities such as hsPDA, but may also be associated with long-term neurodevelopmental impairment in ELBW infants. Future large-scale studies are required to clarify the long-term consequences of hypothermia upon admission.