Comparison 3. Larger gauge atraumatic needles versus smaller gauge atraumatic needles.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 PDPH larger gauge vs smaller gauge	13		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 22 G vs 24 G	1	375	Risk Ratio (M‐H, Random, 95% CI)	0.98 [0.20, 4.81]
1.2 22 G vs 25 G	2	334	Risk Ratio (M‐H, Random, 95% CI)	3.00 [0.32, 28.50]
1.3 24 G vs 25 G	2	647	Risk Ratio (M‐H, Random, 95% CI)	5.62 [1.00, 31.67]
1.4 25 G vs 26 G	3	519	Risk Ratio (M‐H, Random, 95% CI)	0.76 [0.30, 1.90]
1.5 25 G vs 27 G	2	612	Risk Ratio (M‐H, Random, 95% CI)	3.72 [0.59, 23.64]
1.6 26 G vs 27 G	2	258	Risk Ratio (M‐H, Random, 95% CI)	1.79 [0.30, 10.73]
1.7 27 G vs 29 G	1	389	Risk Ratio (M‐H, Random, 95% CI)	1.59 [0.58, 4.37]
2 PDPH by type of surgery	13		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 Caesarean section	6	1263	Risk Ratio (M‐H, Random, 95% CI)	1.92 [0.64, 5.79]
2.2 Orthopaedic procedures	2	392	Risk Ratio (M‐H, Random, 95% CI)	1.24 [0.30, 5.07]
2.3 Other surgeries	5	1479	Risk Ratio (M‐H, Random, 95% CI)	1.44 [0.73, 2.83]
3 PDPH by gender	8		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
3.1 Only women	8	1853	Risk Ratio (M‐H, Random, 95% CI)	1.06 [0.51, 2.20]
4 PDPH by position	10		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
4.1 Sitting position	5	1106	Risk Ratio (M‐H, Random, 95% CI)	0.96 [0.45, 2.06]
4.2 Lateral position	5	992	Risk Ratio (M‐H, Random, 95% CI)	1.88 [0.65, 5.41]
5 AE: paraesthesia	2	439	Risk Ratio (M‐H, Random, 95% CI)	2.19 [0.31, 15.30]
6 AE: backache	4		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
7 Severe PDPH by gauge	8		Risk Difference (M‐H, Random, 95% CI)	Subtotals only
7.1 22 G vs 24 G	1	375	Risk Difference (M‐H, Random, 95% CI)	0.0 [‐0.01, 0.01]
7.2 22 G vs 25 G	1	234	Risk Difference (M‐H, Random, 95% CI)	0.0 [‐0.02, 0.02]
7.3 24 G vs 25 G	1	304	Risk Difference (M‐H, Random, 95% CI)	0.01 [‐0.02, 0.03]
7.4 25 G vs 26 G	2	311	Risk Difference (M‐H, Random, 95% CI)	0.01 [‐0.01, 0.03]
7.5 25 G vs 27 G	1	212	Risk Difference (M‐H, Random, 95% CI)	0.01 [‐0.02, 0.04]
7.6 26 G vs 27 G	1	158	Risk Difference (M‐H, Random, 95% CI)	0.0 [‐0.02, 0.02]
7.7 27 G vs 29 G	1	389	Risk Difference (M‐H, Random, 95% CI)	0.0 [‐0.01, 0.01]
8 Any headache by gauge	7		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
8.1 22 G vs 25 G	1	234	Risk Ratio (M‐H, Random, 95% CI)	2.17 [0.85, 5.51]
8.2 24 G vs 25 G	2	645	Risk Ratio (M‐H, Random, 95% CI)	1.17 [0.49, 2.77]
8.3 25 G vs 26 G	2	311	Risk Ratio (M‐H, Random, 95% CI)	1.13 [0.65, 1.99]
8.4 25 G vs 27 G	1	212	Risk Ratio (M‐H, Random, 95% CI)	1.87 [0.65, 5.39]
8.5 27 G vs 29 G	1	389	Risk Ratio (M‐H, Random, 95% CI)	1.80 [0.85, 3.83]