Predictors of neonatal encephalopathy in full-term infants.
OBJECTIVE
Preliminary investigation of the contribution of adverse antepartum and intrapartum factors to neonatal encephalopathy in singleton neonates born full term.


METHODS
Matched case-control study based on incidence density sampling of controls.


METHODS
Two major teaching hospitals (one paediatric and one obstetric) and three peripheral maternity hospitals in Perth, Western Australia (population 1.2 million).


METHODS
89 cases, all the full term singleton neonates born during an eight month period in 1992 who fulfilled one or more of six criteria during the first week of life (seizures, abnormal conscious state, persistent hypertonia or hypotonia, and feeding or respiratory difficulties of central origin). One full term control infant without neonatal encephalopathy was matched to each case by sex, hospital of delivery, time of day and day of the week of birth, and maternal health insurance status.


METHODS
Odds ratio estimates of relative risk of neonatal encephalopathy associated with antepartum and intrapartum factors.


RESULTS
Estimated incidence of moderate or severe encephalopathy in first week of life was 3.75 per 1000 full term live births. Thirteen cases and no controls had evidence suggestive of important intrapartum hypoxia, and in only five of these cases was the neurological condition at birth attributed to events during the intrapartum period. Univariate conditional logistic regression analysis identified significant differences between cases and controls for maternal vaginal bleeding in pregnancy, maternal thyroxine treatment, congenital abnormalities, induction of labour, interval from membrane rupture to delivery, maternal pyrexia in labour, augmentation of labour, abnormal intrapartum cardiotocograms, and meconium in labour. Family history of convulsions also approached significance.


CONCLUSIONS
Our preliminary results suggest that intrapartum hypoxia, according to currently used criteria, was not the cause of neonatal encephalopathy in most cases in this population. Our findings suggest that many aetiologies of neonatal encephalopathy originate in the antepartum period.
Adamson
S J
SJ
Department of Neonatology, Princess Margaret Hospital for Children, Subiacco, Western Australia.
Alessandri
L M
LM
Badawi
N
N
Burton
P R
PR
Pemberton
P J
PJ
Stanley
F
F
D001927:Brain Diseases / Q000209:etiology* / Q000401:mortality; D016022:Case-Control Studies; D005260:Female; D005311:Fetal Hypoxia / Q000150:complications; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure; D007744:Obstetric Labor Complications; D011247:Pregnancy; D011248:Pregnancy Complications; D012307:Risk Factors; D014904:Western Australia