Comparison 15. Systemic opioids (E) vs placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Cephalic presentation at birth (primary)	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
2 Failure to achieve cephalic vaginal birth (composite outcome: caesarean section + vaginal breech birth)	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
3 Fetal bradycardia (primary)	1	60	Risk Ratio (M‐H, Random, 95% CI)	0.31 [0.09, 1.04]
4 Caesarean section (primary)	1	60	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.63, 1.57]
5 Failed external cephalic version	1	60	Risk Ratio (M‐H, Random, 95% CI)	0.77 [0.47, 1.26]
6 Difficult external cephalic version	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
7 Maternal palpitations	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
8 Maternal headaches	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
9 Maternal hypotension	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
10 Operative vaginal birth	1	60	Risk Ratio (M‐H, Random, 95% CI)	0.94 [0.20, 4.27]
11 Maternal mortality	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
12 Maternal morbidity	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
13 Perinatal mortality	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
14 Perinatal morbidity	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
15 Pain score (0‐10 scale, lowest best) (non‐prespecified)	1	60	Mean Difference (IV, Fixed, 95% CI)	‐1.8 [‐3.04, ‐0.56]
16 Maternal satisfaction score (lower score worst) (non‐prespecified)	1	60	Mean Difference (IV, Fixed, 95% CI)	2.60 [1.25, 3.95]
17 Nausea and vomiting (non‐prespecified)	1	60	Risk Ratio (M‐H, Fixed, 95% CI)	0.31 [0.03, 2.83]
18 Dizziness (non‐prespecified)	1	60	Risk Ratio (M‐H, Fixed, 95% CI)	0.31 [0.01, 7.38]
19 Drowsiness (non‐prespecified)	1	60	Risk Ratio (M‐H, Fixed, 95% CI)	2.81 [0.12, 66.40]