Ten randomised trials with a total of 5,111 participants were included in the meta-analysis: 7 prevention trials and 3 therapy trials. Two studies were unpublished. In the prevention trials, there were 2,561 participants involved in early intervention and 2,441 controls. The therapy trials included only women with an established abnormality in the progress of labour. There were 63 participants involved in early intervention and 46 controls.
The heterogeneity tests for the effect estimates on the major outcomes of interest (the typical OR) were non significant, except for the outcome of epidural analgesia where heterogeneity was significant (chi-squared 6, d.f.=18.4, P=0.0053). Consequently, no OR was calculated for epidural analgesia.
There was no support for the hypothesis that early augmentation reduces the risk of Caesarean section (typical OR 0.9, 95% CI: 0.7, 1.1). In a stratified analysis, the typical OR for the prevention trials was similar to that obtained in the unstratified analysis (typical OR 0.9, 95% CI: 0.7, 1.1). In the therapy trials, there was a non significant reduction in the rate of Caesarean section with early intervention (typical OR 0.6, 95% CI: 0.2, 1.4). However, there was a small number of women in the therapy trials, resulting in a large CI.
Six trials reporting the proportion of women with prolonged labour (duration greater than 9 or 12 hours) found that prolonged labour was markedly reduced by early augmentation (typical OR 0.3, 95% CI: 0.2, 0.4).
An analysis of operative vaginal delivery (both prevention and therapy trials) showed no difference between early augmentation and expectant management (typical OR 0.9, 95% CI: 0.8, 1.1).
Two trials reporting the frequency of postpartum fever found a reduction in the frequency of maternal postpartum fever with early augmentation (typical OR 0.4, 95% CI: 0.3, 0.7). In contrast, 2 trials reporting the frequency of the need for maternal blood transfusion found an increase in transfusion associated with early intervention (typical OR 3.8, 95% CI: 1.2, 11.8). This effect was thought to be mainly due to the effects of one study.
There was no evidence of any difference between the experimental and control groups in the outcome for infants. The typical ORs for the various indicators of neonatal morbidity were reported in the paper.
Two studies found that early augmentation was associated with a reduction in hyperstimulation (typical OR 0.7, 95% CI: 0.5, 1.0), although this effect was observed primarily in only one trial.