Comparison 1. Supplemental IV crystalloid administration for preventing PONV versus control.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Risk of cumulative PON	18	1766	Risk Ratio (M‐H, Random, 95% CI)	0.62 [0.51, 0.75]
2 Risk of early PON	20	2310	Risk Ratio (M‐H, Random, 95% CI)	0.67 [0.58, 0.78]
3 Risk of late PON	17	1682	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.32, 0.69]
4 Risk of early PON, reported as a continuous outcome	5	415	Mean Difference (IV, Random, 95% CI)	‐16.38 [‐21.81, ‐10.96]
5 Risk of late PON reported as a continuous outcome	5	415	Mean Difference (IV, Random, 95% CI)	‐9.62 [‐14.91, ‐4.32]
6 Risk of cumulative POV	20	1970	Risk Ratio (M‐H, Random, 95% CI)	0.50 [0.40, 0.63]
7 Risk of early POV	19	1998	Risk Ratio (M‐H, Random, 95% CI)	0.56 [0.41, 0.76]
8 Risk of late POV	15	1403	Risk Ratio (M‐H, Random, 95% CI)	0.48 [0.29, 0.79]
9 Risk of pharmacologic treatment for PONV	23	2416	Risk Ratio (M‐H, Random, 95% CI)	0.62 [0.51, 0.76]
10 Risk of unintended postoperative admission to hospital	3	235	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.77, 1.43]