Despite improved intrapartum monitoring of the fetus, the rate of cerebral
palsy has not decreased. Many studies now suggest that the majority of
children with such disability may sustain damage in utero. Current
understanding and identification of antenatal brain injury is poor and
individual vulnerability may be important. Specific genotypes such as
Apolipoprotein E are disadvantageous to outcome in the context of adult
brain injury and may also be important in early development.
An aim of this project was to identify clinical and genetic risk factors for
early neonatal mortality within the Scottish population with special
consideration for those infants born in an asphyxiated condition. A further
aim was to determine the prevalence of antenatal brain injury within this
population and to correlate neuropathology with clinical factors.
Clinical data and neuropathological specimens were collected as part of the
Scottish National Perinatal Neuropathology Study from all 22 delivery units
throughout Scotland. Birth asphyxia was defined and infants were classified
accordingly. Neuropathological examination was performed by a single
observer in Edinburgh who was blind to clinical detail. Apolipoprotein E
genotype was analysed and compared with known published data for adults
and healthy newborns. Comparisons of categorical data were made with the
Chi-square test and numerical data were compared using the unpaired
student's t-test or the Mann Whitney U test.
Clinical data was collected from 191 early neonatal deaths. Complications of
pregnancy were common in all neonatal deaths. The only predictive factors
for asphyxia were indicators of intrapartum fetal distress. Neuropathological
examination was possible in 59 infants surviving 3 days or less. Evidence of
prelabour brain injury was observed in nearly half of this cohort, and this
was significantly more common in asphyxiated infants and those who
developed an encephalopathy. The only clinical associations of such damage
were the presence of cardiotocograph abnormalities, meconium staining and
severe depression at birth. Apolipoprotein E analysis was performed in 252
perinatal deaths. There was an over representation of the s4 allele among
healthy newborns compared to perinatal deaths and adults.
Brain injury occurring in utero is a common finding among neonatal deaths,
particularly in those born with asphyxia. Current intrapartum indicators of
fetal distress may signify a fetus who has already suffered compromise prior
to the onset of labour. Differences in the Apolipoprotein s4 genotype in
perinatal populations suggest that the fetus may vary in its ability to
withstand fatal injury.