Comparison 2. Blastocyst‐ versus cleavage‐stage transfer: cumulative pregnancy rate following fresh and frozen transfer.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 Cumulative pregnancy rate from fresh and frozen transfers	5	632	Odds Ratio (M‐H, Fixed, 95% CI)	0.89 [0.64, 1.22]
2.2 Cumulative pregnancy rate per couple: grouped by number of embryos transferred	5	739	Odds Ratio (M‐H, Fixed, 95% CI)	0.88 [0.65, 1.18]
2.2.1 single embryo transfer	1	107	Odds Ratio (M‐H, Fixed, 95% CI)	0.84 [0.39, 1.79]
2.2.2 equal number of embryos transferred	5	632	Odds Ratio (M‐H, Fixed, 95% CI)	0.89 [0.64, 1.22]
2.3 Cumulative pregnancy rate per couple: grouped by prognosis	5	632	Odds Ratio (M‐H, Fixed, 95% CI)	0.89 [0.64, 1.22]
2.3.1 good prognostic factors	2	205	Odds Ratio (M‐H, Fixed, 95% CI)	0.54 [0.30, 0.98]
2.3.2 unselected group	3	427	Odds Ratio (M‐H, Fixed, 95% CI)	1.10 [0.74, 1.61]
2.4 Cumulative pregnancy rate: grouped by day of randomisation	5	632	Odds Ratio (M‐H, Fixed, 95% CI)	0.89 [0.64, 1.22]
2.4.1 randomisation at start of cycle	3	414	Odds Ratio (M‐H, Fixed, 95% CI)	0.81 [0.54, 1.20]
2.4.2 randomised on day of OPU and day 1 after OPU	2	218	Odds Ratio (M‐H, Fixed, 95% CI)	1.06 [0.61, 1.83]
2.5 Cumulative pregnancy rate from fresh and frozen transfers: grouped by vitrification or slow freezing	5		Odds Ratio (M‐H, Fixed, 95% CI)	Subtotals only
2.5.1 slow freezing	4	512	Odds Ratio (M‐H, Fixed, 95% CI)	0.69 [0.48, 0.99]
2.5.2 vitrification	1	120	Odds Ratio (M‐H, Fixed, 95% CI)	2.44 [1.17, 5.12]