Time to redefine prolonged third stage of labor? A systematic review and meta-analysis of the length of the third stage of labor and adverse maternal outcome after vaginal birth.

Objective: This study aimed (1) to assess the association between the length of the third stage of labor and adverse maternal outcome after vaginal birth and (2) to evaluate whether earlier manual placenta removal reduces the risk of adverse outcome.

Data sources: PubMed, MEDLINE, Embase, ClinicalTrials.gov, the Cochrane Library, Journals@Ovid, and the World Health Organization International Clinical Trials Registry were searched from January 1, 2000, to June 13, 2023.

Study eligibility criteria: All studies that assessed adverse maternal outcome, defined as any maternal complication after vaginal birth, concerning the length of the third stage of labor and the timing of manual placenta removal were included.

Methods: The included studies were evaluated using the Conducting Systematic Reviews and Meta-Analyses of Observational Studies of Etiology methodology. Pooled odds ratios with 95% confidence intervals were calculated. Heterogeneity (I² test) was assessed, subgroup analyses were performed, and 95% prediction intervals were calculated.

Results: To meet the first objective, 18 cohort studies were included. The assessed cutoff values for the length of the third stage of labor were 15, 30, and 60 minutes. Women with a third stage of labor of ≥15 minutes had an increased risk of postpartum hemorrhage compared with those with a third stage of labor of <15 minutes (odds ratio, 5.55; 95% confidence interval, 1.74-17.72). For women without risk factors for postpartum hemorrhage, the odds ratio was 2.20 (95% confidence interval, 0.75-6.49). Among women with a third stage of labor of ≥60 minutes vs women with a third stage of labor of <60 minutes, the odds ratio was 3.72 (95% confidence interval, 2.36-5.89). The incidence of red blood cell transfusion was higher for a third stage of labor of ≥30 minutes than for a third stage of labor of <30 minutes (odds ratio, 3.23; 95% confidence interval, 2.26-4.61). Of note, 3 studies assessed the timing of placenta removal and the risk of adverse maternal outcome. However, the results could not be pooled because of the different outcome measures. Moreover, 1 randomized controlled trial (RCT) reported a significantly higher incidence of hemodynamic compromise in women with manual placenta removal at 15 minutes than in women with manual placenta removal at 10 minutes (30/156 [19.2%] vs 10/156 [6.4%], respectively), whereas 2 observational studies reported a lower risk of bleeding among women without manual placenta removal.

Conclusion: Although the risk of adverse maternal outcome after vaginal birth increases when the third stage of labor exceeds 15 minutes, there is no convincing supporting evidence that reducing the length of the third stage of labor by earlier manual removal of the placenta can reduce the incidence of adverse maternal outcome.