A Cochrane review [Abstract] 1 included 6 studies with a total of 2105 women, all at increased risk of complications. Comparison of traditional cardiotocography (CTG) versus no CTG showed no significant difference in perinatal mortality (2.3% vs 1.1%; RR 2.05, 95% CI 0.95 to 4.42; 4 trials, n = 1627) or potentially preventable deaths (RR 2.46, 95% CI 0.96 to 6.30; 4 trials; n = 1627), though the meta-analysis was underpowered to assess this outcome. Similarly, there was no significant difference in caesarean sections (RR 1.06, 95% CI 0.88 to 1.28; 3 trials, n = 1279) nor in the secondary outcomes that were assessed. No studies compared computerised CTG with no CTG.
Another Cochrane review [Abstract] 2 included 13 trials involving over 37 000 women. Continuous CTG showed no difference compared to intermittent auscultation in overall perinatal death rate (RR 0.85, 95% CI 0.59 to 1.23, 11 trials, n = 33 513) or in cerebral palsy (RR 1.75, 95% CI 0.84 to 3.63, 2 trials, n = 13 252), although it was associated with a halving of neonatal seizures (RR 0.50, 95% CI 0.31 to 0.80, 10 trials, n = 32 386). Caesarean sections rates were increased with continuous CTG compared with intermittent auscultation (RR 1.63, 95% CI 1.29 to 2.07, 11 trials, n =18 861), also instrumental vaginal births were increased (RR 1.15, 95% CI 1.01 to 1.33, 10 trials, n = 18 615). The 2 high quality trials were consistent with overall results. Access to fetal blood sampling did not appear to influence any prespecified outcome.
Authors' comment: In order to test the effect of continuous CTG on mortality more than 50 000 women would have to be randomised. Cerebral palsy is more often caused by antepartum, rather than intrapartum, events, and neonatal seizures may have long-term consequences other than cerebral palsy.
FIGO consensus guideline 3 states following: However, studies were carried out in the 1970s, 1980s, and early 1990s where equipment, clinical experience, and interpretation criteria were very different from current practice, and they were clearly underpowered to evaluate differences in major outcomes. Most experts believe that continuous CTG monitoring should be considered in all situations where there is a high risk of fetal hypoxia/acidosis, whether due to maternal health conditions (such as vaginal hemorrhage and maternal pyrexia), abnormal fetal growth during pregnancy, epidural analgesia, meconium stained liquor, or the possibility of excessive uterine activity, as occurs with induced or augmented labor. Continuous CTG is also recommended when abnormalities are detected during intermittent fetal auscultation. The use of continuous intrapartum CTG in low-risk women is more controversial, although it has become standard of care in many countries. An alternative approach is to provide intermittent CTG monitoring alternating with fetal heart rate (FHR) auscultation.
Comment:For other outcomes than neonatal seizures the sudies are underpowered to detect differences in clinically important outcomes.
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