Comparison 1. Synbiotics versus control.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Necrotising enterocolitis	6	907	Risk Ratio (M‐H, Fixed, 95% CI)	0.18 [0.09, 0.40]
1.2 All‐cause mortality	6	925	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.33, 0.85]
1.3 Invasive infection	5	707	Risk Ratio (M‐H, Fixed, 95% CI)	0.84 [0.58, 1.21]