Risk factors for hypoxic-ischemic encephalopathy in asphyxiated newborn infants

To determine the risk factors for hypoxic-ischemic encephalopathy (HIE) in asphyxiated newborn infants.

A retrospective study of 17,706 newborns, who were admitted to the Neonatal Unit of King Chulalongkorn Memorial Hospital, from July 1999 till the end of December 2000. 84 infants with perinatal asphyxia were enrolled in the present study. All of the possible risk factors that might have contributed to asphyxia were identified and recorded HIE was diagnosed based on the Modified Sarnat-Sarnat Score for the diagnosis of neonatal encephalopathy. The clinical data of the HIE group were compared with those of the HIE negative group. The categorical data were analyzed for statistical significance (p < 0.05) by Chi-square test or Fisher exact test, or Student t-test. The odds ratio and 95% CI were calculated for those with statistical significance. Stepwise multiple logistic regression analysis used to determine the independent factors that may predispose an infant to HIE.

Inappropriate antenatal care (OR 9.4; 95%CI: 2.6-35.4), post-term gestation (OR 7.4; 95%CI: 1.4-34.8), vacuum extraction (OR 5.4; 95%CI: 1.1-26.8), male (OR 4.8; 95%CI: 1.3-19.1), prolapsed cord (p = 0.01) and 1 and 5-minute Apgar scores, (p < 0.0001) were significant risk factors for HIE. However, by multiple regression analysis, only a 5-minute Apgar score was significantly associated with HIE (p = 0.001).

Sophisticated or expensive equipment is not necessary for the treatment of HIE patient. HIE depends mainly on adequate and effective supportive strategy. The delivery of high risk pregnancies, under obstetric facilities and with appropriate intervention and with good neonatal resuscitation, may prevent the perinatal asphyxia and thereby minimize the occurring of HIE.