The rationale for biochemical monitoring of the fetus.

1. Rates for perinatal mortality and low Apgar scores have not been affected by fetal intensive care (electronic monitoring +/- fetal blood sampling) in any randomized controlled trial to date. 2. Acidosis at birth may be susceptible to improvement by fetal intensive care but has not been tested adequately in more than a few women. 3. Birth asphyxia which is followed by evidence of cerebral dysfunction within the first 48 hours of life can be significantly altered by current technics of fetal intensive care. 4. The evidence suggests that cognitive disorders and cerebral palsy occur as long term sequelae of hypoxic-ischaemic encephalopathy in a small percentage of survivors. However, factors which predate the onset of labour are more likely to be responsible for cerebral palsy than factors associated with labour. 5. Future developments might include the following: (i) To establish that umbilical arterial pH and/or lactate and/or Apgar score is predictive for neonatal outcome such as hypoxic-ischaemic encephalopathy or other markers of asphyxia. (ii) To determine whether umbilical arterial pH and/or lactate is significantly different when continuous biochemical monitoring is used versus traditional intermittent fetal blood sampling, i.e. does continuous monitoring prevent acidosis? In the present state of development of continuous biochemical monitoring technics in labour it seems unlikely that, at the present time, we could answer the larger question of whether such monitoring can prevent the neurological complications of hypoxic-ischaemic encephalopathy and the subsequent developmental problems including cerebral palsy. Finally, we must not forget that labour and delivery represents a relatively small time period in relation to the total duration of pregnancy with a ratio of approximately 1:355. Thus, it is not surprising that many of the problems of neurologic development are difficult to trace back to a particular stage in pregnancy. Careful monitoring of labour and delivery may help to counteract the tendency to blame this period of pregnancy for all subsequent developmental problems of the child.