|Care in Normal Birth (WHO, 1996, 60 p.)|
|2. GENERAL ASPECTS OF CARE IN LABOUR|
|2.7 Monitoring the Fetus during Labour|
These two methods of fetal surveillance have been compared in a number of trials (Haverkamp et al 1976, 1979, Kelso et al 1978, MacDonald et al 1985, Wood et al 1981, Neldam et al 1986). Caesarean section rate and operative vaginal delivery rate were both higher in all the electronically monitored groups. If scalp pH estimations were not available, the increase in caesarean section rates was even higher. There is little evidence that the increased number of interventions in the electronically monitored groups led to substantive benefits for the infants. Perinatal deaths and low Apgar scores were not reduced in the groups with electronic monitoring. Only one measure of neonatal outcome was improved by electronic monitoring, in the largest trial: neonatal seizures (MacDonald et al 1985). A further analysis of this trial suggested that the excess risk of neonatal seizures in the auscultation group was mainly limited to labours that were induced or augmented with oxytocin. The follow-up data of the infants with seizures showed an equal incidence of major neurological disabilities in the groups monitored electronically and by auscultation.
These data have important consequences for fetal surveillance during normal labour. The substantial increase of interventions if labour is monitored electronically is in agreement with the low specificity of the method in low-risk cases, and does not seem to lead to substantive benefits for the infant. The only exception is the occurrence of neonatal seizures. However, these occurred primarily in infants born after the use of oxytocin infusions, and one may rightly ask if labour induced or augmented by oxytocin is to be considered as normal labour. In countries with sophisticated facilities and a high proportion of institutional births labour which is induced or augmented by oxytocin or prostaglandin is considered high-risk, and such labours only take place under the responsibility of the obstetrician; fetal surveillance will then be by electronic monitoring. In a large follow-up study of midwifery care with intermittent auscultation in normal births but electronic monitoring after referral for oxytocin augmentation, the number of neonatal seizures was very low (Van Alten et al 1989, Treffers et al 1990).
Intermittent electronic monitoring is a variation of continuous electronic monitoring. This method is used during a period of half an hour at the start of labour, and subsequently at regular intervals for a period of about twenty minutes. In a randomized trial Herbst and Ingemarsson (1994) compared the method with continuous monitoring: the results in both groups were equally good. Although in this trial the intervention rate was low in both groups, it is to be expected that the method, if widely adopted in normal labour, would have the same disadvantages as continuous monitoring, though they would perhaps be less obvious. These include restriction of movement during the application and low specificity with concomitant interventions. Moreover, its routine use could lead to mistrust of intermittent auscultation, if there is any suggestion that auscultation might be less reliable than electronic monitoring. Of course, routine use of intermittent electronic fetal monitoring must be distinguished from recourse to electronic monitoring (where it is available) where auscultation indicates the possibility of fetal distress; such practice leads to closer attention to deviations from normality in auscultation.
In conclusion, the method of choice for the monitoring of the fetus during normal labour is intermittent auscultation. In many countries it is the only method available for the large majority of women. But also in industrialized countries, where electronic equipment is more easily accessible, auscultation is the method of choice in normal labour. Individualized care of the labouring woman is essential, and this may be achieved more smoothly by the personal contact required by regular auscultation. Only in women with increased risk, such as labours which are induced or augmented, complicated by meconium-stained amniotic fluid or by any other risk factor, does electronic monitoring seem to be advantageous. In the majority of labours without increased risk, electronic monitoring increases the number of interventions with no clear benefit for the fetus and with a degree of additional discomfort for the women.