Table 1 Demographic and cycle characteristics of FETs stratified by the storage time
From: Effects of vitrified cryopreservation duration on IVF and neonatal outcomes
1 | 2 | 3 | 4 | 5 | P1 | P2 | P3 | P4 | |
|---|---|---|---|---|---|---|---|---|---|
Storage time (days) | 1–90 | 91–180 | 181–365 | 366–730 | > 731 | ||||
Storage time (days), mean ± SD | 49.36 ± 18.96 | 122.335 ± 24.63 | 244.44 ± 48.93 | 477.78 ± 98.65 | 1202.82 ± 457.61 | ||||
Number of FET cycles | 20,926 | 6472 | 2237 | 746 | 762 | ||||
Maternal age at the time of vitrification (years), mean ± SD | 32.38 ± 5.01 | 33.32 ± 4.05 | 34.22 ± 3.12 | 33.27 ± 5.89 | 32.16 ± 4.92 | 0.055 | 0.039 | 0.068 | 0.251 |
Maternal age at the time of thawing(years), mean ± SD | 32.44 ± 5.09 | 33.89 ± 5.23 | 35.01 ± 5.37 | 35.00 ± 5.04 | 35.33 ± 4.89 | < 0.001 | < 0.001 | < 0.001 | < 0.001 |
BMI(Body Mass Index,kg/m2 | 22.06 ± 3.42 | 21.86 ± 3.38 | 22.31 ± 3.22 | 22.17 ± 3.25 | 22.24 ± 3.40 | 0.125 | 0.261 | 0.149 | 0.111 |
Stimulation protocols | 0.089 | 0.052 | 0.675 | 0.047 | |||||
No of receiving long agonist protocol, n (%) | 6075(29.03) | 1854(28.66) | 700(31.32) | 225(30.21) | 247(32.44) | ||||
No of receiving antagonist protocol, n (%) | 11,210(53.57) | 3503(54.13) | 1084(48.45) | 358(48.01) | 344(45.11) | ||||
No of receiving short agonist protocol, n (%) | 3641(17.40) | 1115(17.21) | 453(20.23) | 163(21.78) | 171(22.45) | ||||
Fertilization method, n (%) | 0.081 | 0.661 | 0.098 | 0.323 | |||||
IVF | 13,601(65.01) | 4294(66.34) | 1467(65.59) | 493(66.12) | 494(64.88) | ||||
ICSI | 4608(22.02) | 1496(23.11) | 504(22.55) | 162(21.67) | 182(23.87) | ||||
IVF + ICSI | 2717(12.97) | 682(10.56) | 266(11.86) | 91(12.21) | 86(11.25) | ||||
Endometrial preparation program, n (%) | 0.391 | 0.483 | 0.552 | 0.467 | |||||
Natural cycle | 5537(26.46) | 1736(26.83) | 599(26.77) | 194(26.02) | 199(26.15) | ||||
Hormonal replacement cycle | 15,389(73.54) | 4736(73.17) | 1638(73.23) | 552(73.98) | 563(73.85) | ||||
Type of infertility, n (%) | 0.037 | 0.728 | 0.568 | 0.666 | |||||
Primary infertility | 10,283(49.14) | 3050(47.13) | 1109(49.58) | 370(49.60) | 378(49.61) | ||||
Second infertility | 10,643(50.86) | 3422(52.87) | 1128(50.04) | 376(50.40) | 384(50.39) | ||||
Infertility causes, n (%) | |||||||||
Female factor | 13,037(62.30) | 3914(60.48) | 1361(60.84) | 471(63.14) | 464(60.89) | 0.074 | 0.092 | 0.087 | 0.108 |
Male factor | 2534(12.11) | 986(15.23) | 310(13.86) | 121(16.22) | 114(14.96) | < 0.001 | 1.293 | < 0.001 | < 0.001 |
Multiple factors | 5238(25.03) | 1544(23.86) | 557(24.90) | 151(20.24) | 182(23.88) | 0.230 | 0.873 | < 0.001 | 0.356 |
Unexplained infertility | 117(0.56) | 28(0.43) | 9(0.40) | 3(0.40) | 2(0.27) | < 0.001 | < 0.001 | < 0.001 | < 0.001 |
No. of embryos transferred,mean ± SD | 1.68 ± 0.51 | 1.74 ± 0.52 | 1.72 ± 0.54 | 1.72 ± 0.56 | 1.68 ± 0.59 | 0.244 | 0.456 | 0.467 | 0.674 |
Development stage of embryos transferred, n (%) | < 0.001 | < 0.001 | < 0.001 | < 0.001 | |||||
Cleavage stage | 8093(38.67) | 3074(47.50) | 1244(55.61) | 433(58.04) | 368(48.29) | ||||
Blastocyst | 12,833(61.33) | 3398(52.50) | 993(44.39) | 313(41.96) | 394(51.71) | ||||
Embryo quality at transfer, n (%) | 0.314 | < 0.001 | < 0.001 | < 0.001 | |||||
Good-quality embryo | 20,204(96.55) | 6257(96.68) | 2132(95.32) | 694(92.97) | 686(90.04) | ||||
Poor-quality embryo | 722(3.45) | 215(3.32) | 105(4.68) | 52(7.03) | 76(9.96) | ||||
Year of VF, n (%) | < 0.001 | < 0.001 | < 0.001 | < 0.001 | |||||
2004.1–2008.12 | 830(3.97) | 242(3.74) | 99(4.43) | 43(5.76) | 59(7.74) | ||||
2009.1–2013.12 | 4432(21.18) | 938(14.49) | 412(18.42) | 178(23.86) | 130(17.06) | ||||
2014.1–2019.8 | 15,664(74.85) | 5292(81.77) | 1726(77.16) | 525(70.38) | 573(75.20) | ||||