Intrapartum events and cerebral palsy

Early developmental outcomes after newborn encephalopathy

OBJECTIVE

The aim of this study was to ascertain the early developmental status of children who have a history of newborn encephalopathy.

METHODS

A longitudinal follow-up was conducted of a population-based, case-control study of children born in Western Australia between June 1993 and December 1996. The study included 276 term children (>/=37 weeks' gestation) with moderate or severe newborn encephalopathy and 564 unmatched term control subjects. The Griffiths Mental Development Scales was used to ascertain developmental status and a General Quotient (GQ) score. Outcome measures were the Griffiths developmental subscales, GQ, diagnosis of cerebral palsy, and mortality.

RESULTS

Thirty-four patients and 1 control subject died before reaching assessment. Between June 1994 and December 1999, 195 (81%) eligible patients and 445 (79%) eligible control subjects were assessed. Statistically significant differences were found between patients and control subjects for GQ and all developmental subscales. Overall, 39% of patients had a poor outcome as defined by death, cerebral palsy, or a significant degree of developmental delay, compared with 2.7% of control subjects. Furthermore, 62% of those with severe encephalopathy had a poor outcome compared with 25% of those with moderate encephalopathy. Patients with a history of seizures were 3 times more likely to develop cerebral palsy than patients without. Overall, 28 (10.1%) of patients have cerebral palsy.

CONCLUSIONS

These data provide important prognostic information regarding survival and serious disability and indicate that newborn encephalopathy places children at significant risk of developmental delay by their second year. These findings also suggest that comprehensive clinical and educational assessments are required to enable appropriate educational provisions as these infants approach school entry.

Developmental outcomes of newborn encephalopathy in the term infant

Newborn encephalopathy is a clinically defined condition of abnormal neurological behaviours in the newborn period. Though most cases have their origin in the preconceptional and antepartum period, newborn encephalopathy represents a crucial link between intrapartum events and permanent neurological problems in the child. The birth prevalence of newborn encephalopathy ranges from 1.8 to 7.7 per 1000 term live births according to the definition used and the population to which it is applied. Few studies have investigated the outcomes of newborn encephalopathy other than for cases solely attributed to intrapartum hypoxia. These adverse outcomes range from death to cerebral palsy, intellectual disability, and less severe neurological disabilities such as learning and behavioural problems. Outcomes following newborn encephalopathy may vary from country to country with 9.1% of affected babies dying in the newborn period in Western Australia and 10.1% manifesting cerebral palsy by the age of two. These compare to a case fatality of 30.5% in Kathmandu and a cerebral palsy rate of 14.5% by one year of age. The study by Robertson et al which followed children with hypoxic ischaemic encephalopathy found an incidence of impairment of 16% among survivors assessed at 8 years with 42% requiring school resource room help or special classes. This review emphasises the great need for comprehensive clinical and educational assessment as these infants approach school entry to enable appropriate educational provisions to be made.

Red blood cell magnesium and hypoxic-ischaemic encephalopathy

In developing countries, birth asphyxia is frequently associated with hypoxic ischaemic encephalopathy. This has been attributed to inadequate obstetric care but poor nutrition may also be important. This study determines the association between magnesium stores and hypoxic ischaemic encephalopathy. The level of red blood cell magnesium was measured on 572 women in labour and on selected offspring in a teaching hospital in South Africa. Fifty five of the 572 women delivered infants with hypoxic ischaemic encephalopathy and had significantly lower red blood cell magnesium levels (1.40 mmol/l) than controls. In the latter the levels varied somewhat with the mode of delivery, vertex births 1.76 mmol/l, Caesarean sections 1.67 mmol/l and vacuum extractions 1.61 mmol/l. Infants with hypoxic ischaemic encephalopathy had a significantly lower red blood cell magnesium level (1.39 mmol/l) than normal infants (1.61 mmol/l). Fifty four of 55 babies were black and from poor social circumstances and nutritional deficiency may be relevant. Maternal height, age and the duration of labour did not influence the chance of hypoxic ischaemic encephalopathy and affected infants were more likely than normal ones to be meconium stained (50%), to have a low Apgar score (58%) and to need endotracheal intubation at birth (54%). An intervention study in early pregnancy may determine magnesium's role in hypoxic ischaemic encephalopathy associated with asphyxia.

The intrapartum CTG prior to neonatal encephalopathy at term: a case-control study

OBJECTIVE

To compare cardiotocograph (CTG) records during labour in cases of neonatal encephalopathy and matched controls.

DESIGN

Case-control study.

SETTING

Metropolitan area of Perth, Western Australia.

SUBJECTS

Term deliveries complicated by neonatal encephalopathy and controls matched for sex, hospital, time of birth, day of week of birth and maternal health insurance.

MAIN OUTCOME MEASURES

Low fetal heart rate (FHR) variability, FHR accelerations, late decelerations, total Kreb's score and FIGO classification of CTG records.

RESULTS

The neonatal encephalopathy group had significantly more abnormal CTG records (89%) classified according to FIGO, although 52% of control CTG records were also abnormal. CTG records from cases developed significant differences in terms of absence of FHR accelerations and low FHR variability, but not late decelerations, prior to delivery.

CONCLUSION

Given the low incidence of neonatal encephalopathy in this study (7 per 1000) the predictive value of an abnormal CTG record is clinically unhelpful. However, the changes in the FHR in such cases suggest a greater disturbance of fetal (rest-activity) behaviour during labour.

Monitoring technology and the clinical perspective

Currently available technology requires a new look to reduce intervention as well as to improve the detection of the truly at-risk fetus. Iatrogenic causes of so-called fetal distress, in particular the administration of uterotonics without due attention to avoiding hyperstimulation, predominate as a reason for intervention. There needs to be a better definition of the starting point, i.e assessment of the fetal condition and identification of any risk factors, such as oligohydramnios and growth retardation, that might diminish fetal reserve. This will allow 'customization' of surveillance and management according to the needs of each individual fetus. There also needs to be better training and better agreement about the end-point of monitoring. For prospective surveillance, the aim is to avoid rather than to identify damage, and the definition of the appropriate point for intervention needs to come from better consensus on what is and what is not acceptable management based on current knowledge. New technology holds the promise that it can give trended information during labour, allow early recognition of problems and reduce unnecessary intervention. However, there is a need to ensure reliability and reproducibility of the readings before a new method is released. Co-operation with industry is essential, but the roles need to be well defined and the ultimate responsibility for establishing the role of a new technique has to come from the clinicians involved in intrapartum care.

Model to identify potentially preventable cerebral palsy of intrapartum origin

A six stage model was applied to a geographically defined population of 210 singleton children born at term who had a diagnosis of cerebral palsy at 5 years of age. Thirty five children were identified as those most likely to have cerebral palsy of intrapartum origin; in 26 of these there was evidence of suboptimal care. It is suggested that this simple model should be tested on populations of children with cerebral palsy and the underlying principles used when considering the likely cause of cerebral palsy in individual children.