Table 5.

Subgroup analysis on clinical pregnancy rate.

Characteristic	Subgroup analyses				Heterogeneity
	No. of subjects	No. of studies	RR (95% CI)	P-value	I2	P
Age
≥35 years	1,796	6	1.15 (0.85, 1.54)	0.36	72%	0.003
<35 years	2,430	13	1.41 (1.15, 1.74)	0.001	65%	0.0007
Duration of infertility
≥4 years	1,627	11	0.81 (0.71, 0.93)	0.003	69%	0.0004
<4 years	863	2	0.98 (0.84, 1.13)	0.76	58%	0.13
No. of embryos transferred
≥2	1,093	6	0.79 (0.70, 0.88)	<0.0001	33%	0.19
<2	2,307	6	1.02 (0.92, 1.13)	0.07	61%	0.02
Type of sham
Invasive	629	6	1.77 (1.09, 2.86)	0.02	72%	0.003
Non-invasive	3,510	13	1.28 (1.06, 1.53)	0.009	69%	0.0001
Sham points
Yes	1,245	4	0.94 (0.86, 1.03)	0.16	18%	0.30
No	2,894	15	0.82 (0.74, 0.92)	0.0004	71%	<0.0001