Table 5.

Clinical outcomes following transfer of vitrified blastocysts in different storage duration groups.

Storage groups	I	II	III	IV	P-value
Storage duration (months)	1-6	7-12	13-36	37-84
No. of cycles	323	94	61	22
Mean storage duration (months)	3.56 ± 1.46	8.79 ± 1.74	23.08 ± 7.20	47.41 ± 10.91
Age at FET (years)	31.87 ± 3.69	33.43 ± 3.75	33.28 ± 3.67	33.68 ± 3.41	P<0.001
Endometrial thickness (mm)	9.71 ± 1.63	9.68 ± 1.98	9.70 ± 1.74	9.41 ± 1.92	0.894
Number of blastocyst transferred	1.22 ± 0.42	1.17 ± 0.38	1.21 ± 0.41	1.23 ± 0.43	0.744
Number of good-quality blastocyst transferred	1.11 ± 0.32	1.06 ± 0.25	1.11 ± 0.32	1.09 ± 0.29	0.427
Biochemical pregnancy rate	35 (10.8%)	11 (11.7%)	6 (9.8%)	0 (0.0%)	0.422
Implantation rate	211/395 (53.4%)	61/110 (55.5%)	38/74 (51.4%)	19/27 (70.4%)	0.354
Clinical pregnancy rate	190 (58.8%)	53 (56.4%)	34 (55.7%)	17 (77.3%)	0.313
Ongoing pregnancy rate	165 (51.1%)	45 (47.9%)	32 (52.5%)	13 (59.1%)	0.802
Live birth rate	158 (48.9%)	41 (43.6%)	30 (49.2%)	12 (54.5%)	0.745
Miscarriage rate	28 (17.7.%)	11 (20.8%)	2 (5.9%)	3 (17.6%)	0.295
Multiple pregnancy rate	25 (13.2%)	8 (15.1%)	4 (11.8%)	3 (17.6%)	0.901
Ectopic pregnancy rate	1 (0.5%)	0 (0.0%)	0 (0.0%)	1 (5.9%)	0.199

Data are mean ± SD, n (%) or n/N (%).