Canadian Task Force on Preventive Health Care

Full Text Review

Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made.  (Formerly, these situations were captured under a "C Recommendation".)  This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade.  For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.

Intrapartum Electronic Fetal Monitoring

 Contents

Overview

The widespread, increased use of electronic fetal monitoring (EFM) prompted the Task Force in 1989 to examine the evidence regarding the effectiveness of this procedure in the prevention of intrapartum asphyxia and its consequences. At that time there was inconclusive evidence regarding its use in high-risk pregnancies and fair evidence to exclude EFM from routine intrapartum care in low-risk pregnancies. The individual trials justifying this position were reviewed together with new meta-analyses. This resulted in no change in the recommendations of the Task Force.

 Burden of Suffering

The reported incidence of fetal distress has been increasing rapidly in recent years. In Ontario the recorded incidence of fetal distress increased from 2.4 per 100 deliveries in 1979 to 6.4 per 100 deliveries in 1987.<1>

 Maneuver

 Effectiveness of EFM

The Task Force attributes the highest grade of quality to evidence from randomized controlled trials. Eight such trials were identified;<2-9> unfortunately, the total sample sizes for most of the trials were small, and only two had sufficiently large samples to detect important differences in perinatal death rates.<8-9>

All of the eight randomized controlled trials had inclusion or exclusion rules that defined the study populations as either high- or low-risk. Four of the trials examined the effects of EFM in high-risk populations (Table 1)<2-5> and four in low-risk populations (Table 2).<6-9> The technique for EFM was not stated explicitly in the report of one trial,<9> but internal monitoring was used in all the others. The method used in the control groups involved active clinical monitoring by nursing and medical staff. In four studies<3-6> auscultation of the fetal heart was done every 15 minutes in the first stage of labour and at least every 5 minutes in the second stage. In the Dublin trial<8> the heart was auscultated at least every 15 minutes in the first stage and between all contractions in the second stage. In three trials the monitoring technique in the control group was not explicitly defined.<2,7,9>

In the randomized controlled trials involving high-risk pregnancies there were no statistically significant differences in mortality rates between the EFM and clinically monitored groups,<2-6> but this is not surprising given the small sample sizes. One study showed possible benefits of EFM in terms of the measurement of cord blood gas levels and the identification of neurologic signs;<2> however, the authors pointed out that EFM was part of an intensive care strategy that included other specialized services. None of the studies showed statistically significant differences in Apgar scores between the study and control groups. The only consistent statistically significant effect was an increase in the rates of cesarean section and other operative deliveries in the EFM groups.

Two of the small randomized controlled trials that compared EFM with clinical monitoring in low-risk pregnancies showed no significant effect of monitoring on fetal outcomes.<6,7> One trial showed a statistically significant increase in the cesarean section rate<6> and the other an increase in the rate of other operative deliveries<7> in the EFM group.

The Dublin trial<8> was performed on a broadly defined population of 12,964 low-risk women – only 5.7% of the eligible women were excluded because they were considered to be at high risk on the basis of meconium staining or other grounds. Except for an increase in the rate of operative deliveries other than cesarean section and a possible decrease in the rate of neurologic signs there were no statistically significant differences between the EFM and the control groups. More babies in the control group than in the EFM group had neonatal seizures. Long-term follow-up of all infants with neonatal seizures showed no differences in outcome between the two groups: three infants in each group showed clearly abnormal neurologic signs at follow-up one year later.

Obstetric practices in the Dublin institution differed from North American practices, as evidenced by the low baseline rate for cesarean section (2.3% in Dublin versus almost 20% in Canada<1>). Given these differences it may be difficult to extrapolate the results of the Dublin trial to the situation in North America.

Leveno and colleagues,<9> in studying the use of EFM in low-risk pregnancies, allocated patients to either universal or selective EFM depending on the month of admission. The two study groups were similar in ethnic background, age, parity, level of prenatal care received and birth weight. During the selective months the use of EFM was limited to high-risk pregnancies (37% of the total pregnancies), and during the universal months EFM was used in as many cases as possible (79%). Other than the degree of monitoring, the standards of obstetric care did not vary in the alternate study months. There was no significant effect of universal monitoring other than an increased cesarean section rate. A post-hoc analysis of the outcomes in the low-risk group showed similar results. Interestingly, there seemed to be evidence of an increased cesarean section rate specifically for fetal distress in this group.

Systematic Review

  Recommendations of Others

 Conclusions and Recommendations

In high-risk pregnancies there is little sound scientific evidence to support the choice of EFM over intermittent auscultation (at least once every 15 minutes in the first stage of labour and at least once every 5 minutes in the second stage). This does not mean that EFM may not be beneficial in high-risk pregnancies; there is simply insufficient evidence for recommending the exclusion or inclusion of EFM rather than active clinical monitoring in all high-risk pregnancies (C Recommendation). High-risk categories include low gestational age, high maternal age, placenta or cord problems, meconium in the amniotic fluid, hypertension, proteinuria, malpresentation, poor outcome in previous pregnancies and medical complications.

There is fair evidence to exclude EFM from routine intrapartum care in low-risk pregnancies (D Recommendation) because studies have consistently shown no benefit in reducing the risk of perinatal complications and death, whereas they have shown an increased rate of cesarean section and other operative procedures among those monitored. Since the operative procedures are associated with a high risk of maternal complications and increased costs, the routine use of EFM could increase the risk and costs.

 Unanswered Questions (Research Agenda)

 Evidence

Table 1: Characteristics of Randomized Controlled Trials for High Risk Pregnancies

¹ n.s. indicates no significant difference; n/a is not available and higher or better are statistically significant
differences at p<0.05.
 

Table 2: Characteristics of Randomized Controlled Trials for Low Risk Pregnancies

¹ Post hoc analysis of low risk subgroup by Leveno et al.<9>
² n.s. indicates no significant difference; n/a is not available and higher or better are statistically significant
differences at p<0.05.

 Full Citation

• Anderson G. Intrapartum electronic fetal monitoring. In: Canadian Task Force on the Periodic Health Examination. Canadian Guide to Clinical Preventive Health Care. Ottawa: Health Canada, 1994; 158-65.

Link to Structured Abstract of this review

Link to Summary Table of this review

Link to Selected References list of this review

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