Comment:The quality of evidence is downgraded by study limitations (unclear allocation concealment and blinding of outcome assessment).
A Cochrane review [Abstract] 1 included 30 studies with a total of 9015 participants. Methodological quality of the trials was variable. Compared with supine positions, the upright position was associated with a reduction in duration of second stage in the upright group (MD -6.16 minutes, 95% CI -9.74 to -2.59 minutes; 19 trials; 5811 women; P = 0.0007; random-effects; I² = 91%; very low-quality evidence) in all women (primigravid and multigravid); however, this result should be interpreted with caution due to large differences in size and direction of effect in individual studies. Upright positions were also associated with no clear difference in the rates of caesarean section (RR 1.22, 95% CI 0.81 to 1.81; 16 trials; 5439 women; low-quality evidence), a reduction in assisted deliveries (RR 0.75, 95% CI 0.66 to 0.86; 21 trials; 6481 women; moderate-quality evidence), a reduction in episiotomies (average RR 0.75, 95% CI 0.61 to 0.92; 17 trials; 6148 women; random-effects; I² = 88%), a possible increase in second degree perineal tears (RR 1.20, 95% CI 1.00 to 1.44; 18 trials; 6715 women; I² = 43%; low-quality evidence), no clear difference in the number of third or fourth degree perineal tears (RR 0.72, 95% CI 0.32 to 1.65; 6 trials; 1840 women; very low-quality evidence), increased estimated blood loss greater than 500 mL (RR 1.48, 95% CI 1.10 to 1.98; 15 trials; 5615 women; I² = 33%; moderate-quality evidence), fewer abnormal fetal heart rate patterns (RR 0.46, 95% CI 0.22 to 0.93; 2 trials; 617 women), no clear difference in the number of babies admitted to neonatal intensive care (RR 0.79, 95% CI 0.51 to 1.21; 4 trials; 2565 infants; low-quality evidence). On sensitivity analysis excluding trials with high risk of bias, these findings were unchanged except that there was no longer a clear difference in duration of second stage of labour (MD -4.34, 95% CI -9.00 to 0.32; 21 trials; 2499 women; I² = 85%).
In primigravid women the use of any upright compared with supine positions was associated with: non-significant reduction in duration of second stage of labour (mean 3.24 minutes, 95% CI 1.53 to 4.95 minutes; 9 trials) - this reduction was largely due to women allocated to the use of the birth cushion.
A meta-analysis 2 6 trials. There was a reduction in duration of second stage of labor among women in a flexible sacrum birthing position, with a mean duration from 3.2 to 34.8 minutes. The pooled weighted mean difference with random effect model was 21.12 (95% CI 11.84-30.34) minutes, with a significant heterogeneity between the studies (I² = 96.8%, p < 000).
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