We pooled the data from seven studies in which the duration
of first stage of labor was recorded. A total of 2,166
patients were enrolled in those trials [2,10-15]. Two studies
accounted for 78.2% (1,694 patients) of all patients
enrolled [10,14]. The reviewers observed performance
bias in one of these two studies (reporting on 627 randomized
women) [10] because of delayed amniotomy in
the study group. Another study included in this section
randomized only patients with protracted labor [11].
Despite these observations, results favored intervention
(WMD (random) -0.83 hours; 95%CI -1.60 to -0.06) (Figure
2).