Table 5 Non-prespecified outcomes for cumulative live births including the long-term follow-up cohort (Intention-to-Treat Analysis)^a

Outcomes, No./total (%)	Blastocyst-stage embryo transfer group (n = 497)	Cleavage-stage embryo transfer group (n = 495)	Absolute difference (95% CI)^b	Relative risk (95% CI)	P value^c
Cumulative live births	402 (80.9%)	384 (77.6%)	3.3% (−1.7 to 8.4)	1.04 (0.98 to 1.11)	0.199
Singleton live births	391 (78.7%)	375 (75.8%)	2.9% (−2.3 to 8.1)	1.04 (0.97 to 1.11)	0.274
All twin live births	11 (2.2%)	9 (1.8%)	0.4% (−1.4 to 2.1)	1.22 (0.51 to 2.91)	0.658
No. of unused frozen embryos, mean (SD)	3.9 (3.4)	5.2 (4.1)	−1.3 (−1.8 to −0.9)	-	3.87e-08
No. of unused frozen embryos in women with a live birth, mean (SD)	4.5 (3.3)	5.9 (4.0)	−1.4 (−1.9 to −0.9)	-	1.03e-07
No. of unused frozen embryos in women without a live birth, mean (SD)	1.2 (1.9)	2.8 (3.8)	−1.6 (−2.4 to −0.7)	-	0.00035
No. of women without a frozen embryo	89 (17.9%)	65 (13.1%)	4.8% (0.3 to 9.3)	1.36 (1.02 to 1.83)	0.038
No. of women without a frozen embryo without a livebirth	58 (11.7%)	53 (10.7%)	1.0% (−3.0 to 4.9)	1.09 (0.77 to 1.55)	0.631
No. of women without a frozen embryo with a livebirth	31 (6.2%)	12 (2.4%)	3.8% (1.3 to 6.3)	2.57 (1.34 to 4.95)	0.003

Non-inferiority P value = 1.16e-07 for cumulative live births (with margin = −0.1, α = 0.025, one-sided).
SD standard deviation.
^aThis is a secondary, post-hoc analysis of the long-term follow-ups from randomization day to July 28th, 2023, and treatment after the study period (1 year of randomization) did not follow our prespecified protocol, reflecting real-world practice.
^bAbsolute differences in percentages are indicated in percentage points, and absolute differences in other values are indicated in units of that value.
^cAll P values are for superiority, two-sided. No adjustments were made for multiple comparisons. Two-sample t-test was used for continuous data; Chi-square test was used for categorical data.

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