Table 2 Pregnancy outcomes of FETs stratified by the storage time

survival rate

98.63 (34,853/35338)

94.53 (11,442/12104)

84.62 (3940/4656)

80.75 (1313/1626)

71.13 (1281/1801)

 < 0.001

 < 0.001

 < 0.001

 < 0.001

Implantation rate

42.28(14,940/35338)

34.65(3965/11442)

30.18(1189/3940)

32.52(427/1313)

35.21(451/1281)

 < 0.001

 < 0.001

 < 0.001

 < 0.001

Positive HCG rate

57.85(12,106/20926)

49.75(3220/6472)

44.43(994/2237)

46.38(346/746)

49.87(380/762)

 < 0.001

 < 0.001

 < 0.001

 < 0.001

Clinical Pregnancy rate

55.26(11,563/20926)

47.54(3077/6472)

42.02(940/2237)

43.70(326/746)

47.64(363/762)

 < 0.001

 < 0.001

 < 0.001

 < 0.001

Multiple pregnancy rate

30.52(3529/11563)

29.54(909/3077)

27.45(258/940)

30.98(101/326)

25.34(92/363)

0.251

 < 0.001

0.682

 < 0.001

Live birth rate

32.11(6719/20926)

30.18(1953/6472)

28.12(629/2237)

29.22(218/746)

27.53(210/762)

 < 0.001

 < 0.001

 < 0.001

 < 0.001

Ectopic pregnancy rate

1.59(184/11563)

2.08(64/3077)

1.91(18/940)

2.15(7/326)

1.93(7/363)

 < 0.001

 < 0.001

 < 0.001

 < 0.001