Only a minor part of cerebral palsy cases begin in labour

But still room for controversial childbirth issues in court

Education and debate p 1054

Cerebral palsy develops in 2-3 out of 1000 live births during the first years of life. Its association with complications during childbirth has led to much controversy—and much litigation. This issue of the BMJ contains an international consensus statement on what is known about the causal relation between acute intrapartum events and cerebral palsy (p 1054).1 The statement has been produced by an international task force representing a wide range of sciences, clinical specialties, and professional associations. The document is based on a thorough multidisciplinary literature review with the intention of benefiting research into the causation and prevention of cerebral palsy and helping those who counsel in this field or who offer expert opinion in court.

The common assumption is that perinatal asphyxia is the usual cause of cerebral palsy in term babies.2 A few years ago a consensus statement from the Australian and New Zealand perinatal societies concluded, “There is no evidence that current obstetric practices can reduce the risk of cerebral palsy The origins of many cases of cerebral palsy are likely to be antenatal.”3 Important Australian studies have shown that intrapartum hypoxia alone accounts for only a small proportion of cases of newborn encephalopathy and later cerebral palsy.4 5 A realistic estimate may be that around 10% of cases of cerebral palsy stem from adverse intrapartum events.2 The consensus statement published in this issue underlines this new insight into the origin of cerebral palsy. It points to events before labour or the newborn period as the main cause of cerebral palsy This message is important because of the common opinion among the public, and also among some physicians, that cerebral palsy stems from intrapartum events.

The report presents three essential criteria that have to be met for a case of cerebral palsy to be causally linked to an acute intrapartum hypoxic event. The cerebral palsy should be of the spastic quadriplegic or dyskinetic type. There should be early onset of severe or moderate neonatal encephalopathy in a baby born at 34 weeks or later. And there should be evidence of metabolic acidosis in intrapartum fetal, umbilical arterial cord, or very early neonatal blood samples (pH <7.00 and base deficit ≤12 nmol/l). These are strict criteria In particular, providing evidence of metabolic acidosis will create difficulties as pH and base deficit measurements will not be available at smaller hospitals and certainly not at home deliveries.

In addition to these essential criteria, the report presents five other criteria that together suggest an intrapartum timing but which by themselves are non-specific. Some of these criteria—for example “early imaging evidence of acute cerebral abnormality,” can be ascertained only when the delivery takes place at a technically advanced hospital. This means that meeting the criteria to define an acute intrapartum hypoxic event and thereby assume a causal relation with cerebral palsy will depend on the place of delivery. Unexpected adverse events in smaller hospitals or outside hospital will have to be judged based mainly on clinical observations as before. Nevertheless, the criteria and the accompanying comments in the consensus document represent important support for expert opinions in court, although some of the controversial issues will still persist.6

Research on the causation of cerebral palsy needs to focus more on antenatal events. Evaluation of the condition of the fetus in utero is likely to be greatly facilitated by new technology.2 There is also a need for detailed follow up of newborn babies and their later development. Medical registries of births and their immediate outcomes have long existed in some countries. Thus, fetal age, birth weight, and health status at childbirth have been well documented over the past three decades in Denmark, Norway, and Sweden. In none of these countries, however, are there any systematic nationwide follow up data on the children. This is necessary to enable appropriate surveillance of long term outcomes such as cerebral palsy. Such surveillance, however, has been established in Western Australia, based on a systematic follow up of births recorded in the state's medical birth registry.7 8 The follow up data provide the opportunity for public health surveillance in an important health sector. But they have also been of great importance in perinatal research, particularly into cerebral palsy.7^–10

Over the past decades smaller and smaller babies have survived a preterm delivery. The association between preterm birth below 34 weeks of gestation and cerebral palsy, however, is not dealt with in any detail in the consensus document.

Future generations might criticise the medical and public health authorities in the latter part of the 20th century for not having established proper surveillance of perinatal care and its consequences, along with the consequences of the tremendous development of medical technology surrounding pregnancy, childbirth, and the neonatal period. In thenear future, however, regardless of proper surveillance and new insights, in most casesof cerebral palsy there will be nothing or nobody to blame. Focus should therefore be on the provision of optimal care for infants with cerebral palsy and their families.