Comparison 5. Complications during primary hospitalisation.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Infection	18	1349	Risk Ratio (M‐H, Fixed, 95% CI)	1.14 [0.97, 1.34]
2 Hyperglycaemia	17	1291	Risk Ratio (M‐H, Fixed, 95% CI)	1.51 [1.26, 1.81]
3 Glycosuria	2	48	Risk Ratio (M‐H, Fixed, 95% CI)	8.03 [2.43, 26.52]
4 Hypertension	15	1235	Risk Ratio (M‐H, Fixed, 95% CI)	2.12 [1.45, 3.10]
5 New cranial echodensities	1	18	Risk Ratio (M‐H, Fixed, 95% CI)	7.0 [0.41, 118.69]
6 Necrotising enterocolitis (NEC)	9	1016	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.61, 1.74]
7 Gastrointestinal bleeding	7	992	Risk Ratio (M‐H, Fixed, 95% CI)	1.38 [0.99, 1.93]
8 Gastrointestinal perforation	3	159	Risk Ratio (M‐H, Fixed, 95% CI)	1.60 [0.28, 9.31]
9 Severe retinopathy of prematurity (ROP)	12	558	Risk Ratio (M‐H, Fixed, 95% CI)	1.38 [1.07, 1.79]
10 Severe ROP in survivors	9	416	Risk Ratio (M‐H, Fixed, 95% CI)	1.31 [0.99, 1.74]
11 Hypertrophic cardiomyopathy	4	238	Risk Ratio (M‐H, Fixed, 95% CI)	2.76 [1.33, 5.74]
12 Pneumothorax	3	157	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.53, 1.49]
13 Severe intraventricular haemorrhage (IVH)	5	247	Risk Ratio (M‐H, Fixed, 95% CI)	0.44 [0.19, 1.02]