The main goal of monitoring the baby’s condition during labour is to recognise in time and then prevent complications that can occur when labour becomes distressing for the baby and leads to fetal metabolic acidosis and cerebral hypoxia. Of course, the link between more or less permanent brain injury and metabolic acidosis is complex and depends mainly on how much time and which harmful factors the baby is exposed to, and on the baby’s condition at the start of labour. What’s more, today it is clear that most serious and permanent damage to the baby’s brain occurs already during pregnancy, before labour.
When, in the 1960s, a method emerged that enabled reliable continuous monitoring of the baby’s heart rate (CTG), many probably thought it would solve most obstetric problems related to fetal distress. Unfortunately, time has shown that this is far from the case. Above all, it is an indirect method that does not show the full spectrum of the baby’s condition. It is true that when we see a normal (reassuring) CTG, we can conclude that the baby’s condition is currently good. However, we do not know exactly what the baby’s long-term condition is, what impact labour will have on them, or how significant the various suspicious or pathological CTG changes that may appear during labour are.
The fact is that we introduced and adopted continuous fetal heart rate monitoring during labour without serious, controlled research. In doing so, we have demonstrably increased the frequency of obstetric interventions (operative vaginal delivery, caesarean section), while at the same time we have not improved perinatal outcomes in a statistically significant way. What’s more, we have opened up an entire field of medico-legal problems, where individuals—often influenced by legal or other “experts”—cannot understand that continuous fetal heart rate monitoring is still often not fully defined and is only an indirect reflection of the baby’s actual condition.
Because of this, many more or less justified criticisms of continuous fetal heart rate monitoring have emerged:
– insufficient understanding of (patho)physiology,
– overly indirect assessment of the baby’s condition,
– a relatively high possibility of technical error,
– differences in signal acquisition technique,
– still incomplete or inconsistently accepted classification,
– significant differences in interpretation among the same or different
assessors,
– a high proportion of false-positive findings,
– originally intended as a screening method, but too often already used as a
diagnostic method,
– often leads to a higher rate of obstetric interventions,
– still too little consensus on how, when, and whom we should monitor, etc.
Of course, interpreting the available evidence on the usefulness of CTG is far more complex than simply dismissing the method as such. On the one hand, important events such as cerebral palsy are rare, and the number of participants included in existing studies is still not large enough to statistically confirm a reduction in such rare events. On the other hand, we are all aware that it is often the interpretation of the CTG trace that does not stand up to critical professional review.
Today, there is clear evidence that continuous fetal heart rate monitoring is an important method that improves perinatal outcomes in the group of pregnant women at high risk of complications. In the group of pregnant women at low risk of complications, it seems that intermittent fetal heart rate monitoring achieves the same perinatal outcomes for the baby, with fewer obstetric interventions. We need to be aware that intermittent fetal heart rate monitoring, when following the recommendations you can find among the articles, often means a more actively involved midwife than when the labouring woman is simply “hooked up” to a CTG monitor. We can reasonably ask whether this really is the same care for such women in labour, and what the results obtained in this way actually mean.
