Table 2.

Cycle characteristics

	Did not survive warming (n = 175)	Survived warming (n = 5992)	p value
Ovarian stimulation protocol			0.38
GnRH antagonist	90.3% (158/175)	86.7% (5195/5992)
GnRH agonist downregulation	2.3% (4/175)	2.4% (146/5992)
Microdose GnRH agonist	7.4% (13/175)	10.9% (651/5992)
Year of cycle			< 0.001
Before 2015	24.6% (43/175)	13.2% (790/5992)
2015 and after	75.4% (132/175)	86.8% (5202/5992)
Cumulative gonadotropin dose (IU)	3365.8 ± 1274.6	3465.2 ± 1290.2	0.32
Estradiol at surge (pg/mL)	2754.8 ± 1390.2	2523.1 ± 1190.6	0.03
Progesterone at surge (ng/mL)	1.0 ± 0.9	0.9 ± 0.6	0.15
Oocytes retrieved	19.6 ± 10.7	17.5 ± 9.8	0.005
Fertilization method			0.12
Conventional	0.0% (0/175)	1.6% (94/5976)
ICSI	100.0% (175/175)	98.4% (5882/5976)
Cleavage stage—cell number	8.8 ± 2.1	8.7 ± 1.8	0.45
Cleavage stage—% fragmentation	2.0 ± 4.2	2.7 ± 5.4	0.09
Day of embryo development at cryopreservation			< 0.001
5	37.7% (66/175)	58.3% (3494/5992)
6	53.1% (93/175)	38.7% (2319/5992)
7	9.1% (16/175)	3.0% (179/5992)
Number of trophectoderm biopsies			< 0.001
1	93.1% (163/175)	97.7% (5857/5992)
2	6.9% (12/175)	2.3% (135/5992)
Number of times vitrified and warmed			0.19
1	99.4% (174/175)	97.6% (5850/5992)
2	0.6% (1/175)	2.4% (142/5992)
Embryo sex			0.74
Male	47.7% (83/174)	49.3% (2941/5969)
Female	52.3% (91/174)	50.7% (3028/5969)
Expansion grade			< 0.001
2	0.0% (0/175)	0.0% (1/5992)
3	0.0% (0/175)	0.2% (10/5992)
4	29.1% (51/175)	49.7% (2980/5992)
5	29.7% (52/175)	37.9% (2269/5992)
6	41.1% (72/175)	12.2% (732/5992)
ICM grade			< 0.001
A	59.4% (104/175)	65.0% (3892/5992)
B	25.1% (44/175)	27.3% (1635/5992)
C	15.4% (27/175)	7.7% (460/5992)
D	0.0% (0/0)	0.001% (3/5992)
Trophectoderm grade			0.02
A	49.1% (86/175)	39.3% (2350/5981)
B	32.6% (57/175)	42.4% (2535/5981)
C	18.3% (32/175)	18.3% (1096/5981)
D	0.0% (0/0)	0.002% (10/5981)