Table 3.

Results of sensitivity analysis

Sensitivity analysis	Heterogeneity		Pooled analysis
	I 2 (%)	P value	RR (95 % CI)	P value
Include Vatne et al.’s study	39	0.08	2.32 (1.59, 3.38)	<0.0001
Exclude Vatne et al.’s study	0	0.67	2.74 (2.05, 3.65)	<0.0001