Table 1.

Baseline and fresh cycle treatment characteristics of the study population 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	612	202	141	76
Age at OPU (years)	31.86 ± 3.72	31.93 ± 3.55	31.30 ± 3.58	29.49 ± 2.82	P<0.001
Body mass index (kg/m²)	21.76 ± 3.36	21.88 ± 3.41	21.74 ± 2.95	21.18 ± 2.45	0.446
Primary infertility	270 (44.1%)	97 (48.0%)	73 (51.8%)	35 (46.1%)	0.377
Duration of infertility (years)	3.79 ± 2.62	4.13 ± 3.15	3.87 ± 2.79	3.57 ± 2.84	0.364
bFSH (IU/L)	6.72 ± 2.24	6.54 ± 1.94	6.54 ± 1.77	6.68 ± 1.72	0.657
AFC	14.66 ± 5.30	15.34 ± 5.21	16.23 ± 5.10	17.80 ± 5.35	P<0.001
Previous embryos transferred	2.09 ± 0.90	2.23 ± 0.91	2.28 ± 0.86	2.33 ± 1.05	0.020
Previous good-quality embryos transferred	1.90 ± 0.71	2.04 ± 0.66	2.03 ± 0.65	2.16 ± 0.57	0.001
Total gonadotropin dose (IU)	2580.45± 899.10	2539.25± 983.77	2356.38± 915.70	2201.65± 873.80	0.001
Estradiol level on HCG trigger day (pmol/L)	12936.93± 10029.92	11841.97± 8047.12	11873.93± 9155.30	13662.59± 11418.36	0.276
Number of oocytes retrieved	11.39 ± 4.09	11.40 ± 4.01	11.01 ± 3.66	11.38 ± 4.11	0.786
Fertilization method
IVF	452 (73.9%)	143 (70.8%)	102 (72.3%)	56 (73.7%)	0.855
ICSI	120 (19.6%)	47 (23.3%)	25 (17.7%)	17 (22.4%)	0.560
IVF+ICSI	2 (0.3%)	2 (1.0%)	0 (0.0%)	0 (0.0%)	0.484
Normal fertilization rate (%)	72.80 ± 16.53	72.71 ± 17.66	73.87 ± 15.64	73.99 ± 16.02	0.848
Number of available embryos on D3	6.39 ± 2.47	6.32 ± 2.20	6.40 ± 2.28	6.26 ± 2.13	0.958
Number of good quality embryos on D3	4.10 ± 1.85	4.02 ± 1.68	4.29 ± 1.80	4.24 ± 1.67	0.515

bFSH, baseline follicle stimulating hormone. Data are mean ± SD or n (%).