Comparison 1. Blastocyst‐ versus cleavage‐stage transfer: live birth rate following fresh transfer.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Live birth per couple	15	2219	Odds Ratio (M‐H, Fixed, 95% CI)	1.27 [1.06, 1.51]
1.2 Live birth per couple: grouped by number of embryos transferred	15	2677	Odds Ratio (M‐H, Fixed, 95% CI)	1.30 [1.10, 1.53]
1.2.1 More cleavage‐stage than blastocyst embryos transferred	6	483	Odds Ratio (M‐H, Fixed, 95% CI)	1.51 [1.03, 2.22]
1.2.2 Single embryo transfer	2	458	Odds Ratio (M‐H, Fixed, 95% CI)	1.47 [0.98, 2.20]
1.2.3 Equal number of embryos transferred	9	1736	Odds Ratio (M‐H, Fixed, 95% CI)	1.21 [0.99, 1.47]
1.3 Live birth rate per couple: grouped by prognosis	15		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
1.3.1 good prognostic factors	9	1514	Odds Ratio (M‐H, Fixed, 95% CI)	1.28 [1.04, 1.59]
1.3.2 poor prognostic factors	2	77	Odds Ratio (M‐H, Fixed, 95% CI)	2.05 [0.53, 7.96]
1.3.3 unselected group	4	628	Odds Ratio (M‐H, Fixed, 95% CI)	1.19 [0.86, 1.66]
1.4 Live birth rate: grouped by day of randomisation	15		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
1.4.1 randomisation at start of cycle	6	1207	Odds Ratio (M‐H, Fixed, 95% CI)	1.08 [0.84, 1.38]
1.4.2 randomised on day of OPU and day 1 after OPU	5	566	Odds Ratio (M‐H, Fixed, 95% CI)	1.16 [0.82, 1.65]
1.4.3 randomised day 2 to 3 post‐OPU	2	364	Odds Ratio (M‐H, Fixed, 95% CI)	2.17 [1.42, 3.33]
1.4.4 day of randomisation unstated	2	82	Odds Ratio (M‐H, Fixed, 95% CI)	1.71 [0.67, 4.39]