Table 2. Comparison of reproductive outcomes from fresh and frozen-thawed embryo transfers, according to embryo development stage.
Outcomes	Cleavage (%)	Blastocyst (%)	p value a	OR	95% CI
Fresh ET
Implantation	22	47	0.0005	0.3209	0.1712- 0.6018
Clinical pregnancy	34	64	0.0057	0.2918	0.1231- 0.6918
Ongoing pregnancy	30	61	0.0046	0.2730	0.1150- 0.6482
Live births	28	55	0.0154	0.3268	0.1385- 0.7712
Frozen-thawed ET
Implantation	27	39	NS	0.5691	0.2991- 1.083
Clinical pregnancy	43	53	NS	0.66	0.2855- 1.526
Ongoing pregnancy	36	45	NS	0.6878	0.2928 - 1.616
Live births	36	40	NS	0.8187	0.3467- 1.933
Outcomes presented: Implantation: the ratio of the number of fetal hearts to the number of embryos transferred; Clinical pregnancy: an ultrasound confirmed fetal heart after the 6th gestational week; Ongoing pregnancy: pregnancy continued after the 14th gestational weekET = embryo transfer; NS = not significant; OR = odds ratio; CI = confidence interval aStatistical analysis performed by unpaired t-test or Mann-Whitney test or Fisher’s exact test