Comparison 1. Intravenous in‐line filter versus no filter.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mortality during hospitalisation	2	530	Risk Ratio (M‐H, Fixed, 95% CI)	0.87 [0.52, 1.47]
2 Risk of proven septicaemia per infant	2	530	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.59, 1.27]
3 Rates of proven septicaemia per 1000 catheter day	1		Rate Ratio (Fixed, 95% CI)	0.79 [0.45, 1.37]
4 Localised phlebitis	3	641	Risk Ratio (M‐H, Fixed, 95% CI)	1.22 [0.40, 3.77]
5 Suspected septicaemia	1	88	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.18, 1.81]
6 Localised thrombi	1	88	Risk Ratio (M‐H, Fixed, 95% CI)	0.2 [0.01, 4.05]
7 Proven necrotising enterocolitis	1	88	Risk Ratio (M‐H, Fixed, 95% CI)	0.2 [0.01, 4.05]
8 Composite thrombus, proven or unproven sepsis, necrotising enterocolitis	1	88	Risk Ratio (M‐H, Fixed, 95% CI)	0.38 [0.19, 0.77]