Table 1 Comparison of baseline characteristics

Maternal age, median(IQR)(year)^U

38.5(38.0,39.4)^{a, b,c}

35.7(35.1,36.4)^{d, e}

32.1(30.9,33.3)^f

27.6(26.0,28.8)

< 0.001^*

Male age, mean(SD)(year)

39.66 ± 4.61^{a, b,c}

37.68 ± 3.62^{d, e}

34.05 ± 3.49^f

29.98 ± 3.41

< 0.001^*

Infertility duration, median(IQR)(year)^U

2.0(1.0,4.0)^c

3.0(2.0,6.0)^{d, e}

3.0(1.0,5.0)^f

3.0(2.0,4.0)

0.060

BMI, median(IQR)(kg/m2)^U

21.48(20.03,23.31)

21.49(19.98,23.88)

21.10(19.29,23.62)

20.96(19.21,23.44)

0.076

Infertility type

Primary infertility%(n)

8.2(12/147)^{a, b,c}

18.3(30/164)^{d, e}

37.5(181/483)^f

56.5(274/485)

<0.001^*

Secondary infertility%(n)

91.8(135/147)^{a, b,c}

81.7(134/164)^{d, e}

62.5(302/483)^f

43.5(211/485)

< 0.001^*

Infertile causes

Female factor%(n)^#

57.8(85/147)

65.2(107/164)

62.1(300/483)

61.9(300/485)

0.610

Male factor%(n)

21.1(31/147)^{b, c}

15.2(25/164)

11.2(54/483)

14.0(68/485)

0.023^*

Both factors%(n)^

11.6(17/147)

8.6(14/164)^e

13.2(64/483)

15.4(75/485)

0.134

Unexplained factor%(n)

9.5(14/147)

11.0(18/164)

13.5(65/483)^f

8.7(42/485)

0.109

Transplant cycle

First cycle%(n)

61.9(91/147)^c

57.9(95/164)^{d, e}

69.4(335/483)

71.1(345/485)

0.005^*

Second cycle%(n)

38.1056/147)^c

42.1(69/164)^{d, e}

30.6(148/483)

28.9(140/485)

0.005^*

History of diabetes

Yes%(n)

0.7(1/147)

0.6(1/164)

0.8(4/483)

0.2(1/485)

0.472

No%(n)

99.3(146/147)

99.4(163/164)

99.2(479/483)

99.8(484/485)

0.472

History of hypertension

Yes%(n)

2.0(3/147)

1.8(3/164)

0.8(4/483)

0.4(2/485)

0.121

No%(n)

98.0(144/147)

98.2(161/164)

99.2(479/483)

99.6(483/485)

0.121

History of thyroid disease

Yes%(n)

0.7(1/147)

0(0/164)

1.5(7/483)

1.9(9/485)

0.324

No%(n)

99.3(146/147)

100(164/164)

98.5(476/483)

98.1(476/485)

0.324

History of male smoking

Yes%(n)

17.0(25/147)

17.1(28/164)

17.0(82/483)

18.6(90/485)

0.919

No%(n)

83.0(122/147)

82.9(136/164)

83.0(401/483)

81.4(395/485)

0.919

Number of births

0%(n)

28.6(42/147)^{a, b,c}

49.4(81/164)^{d, e}

67.3(325/483)^f

87.8(426/485)

< 0.001^*

1–2%(n)

70.7(104/147)^{a, b,c}

50.0(82/164)^{d, e}

32.1(155/483)^f

12.2(59/485)

< 0.001^*

≥ 3%(n)

0.7(1/147)

0.6(1/164)

0.6(3/483)

0(0/485)

0.193

Number of miscarriages

0%(n)

25.2(37/147)^{a, b,c}

36.6(60/164)^{d, e}

52.4(253/483)^f

62.1(301/485)

< 0.001^*

1–2%(n)

51.0(75/147)^{b, c}

48.2(79/164)^{d, e}

37.5(181/483)

33.2(161/485)

< 0.001^*

≥ 3%(n)

23.8(35/147)^{b, c}

15.2(25/164)^e

10.1(49/483)^f

4.7(23/485)

< 0.001^*

Number of pregnancies

0%(n)

8.2(12/147)^{a, b,c}

18.3(30/164)^{d, e}

37.5(181/483)^f

56.5(274/485)

< 0.001^*

1–2%(n)

51.7(76/147)^c

54.9(90/164)^{d, e}

44.3(214/483)^f

34.4(167/485)

< 0.001^*

≥ 3%(n)

40.1(59/147)^{a, b,c}

26.8(44/164)^{d, e}

16.2(78/483)^f

9.1(44/485)

< 0.001^*

Number of early spontaneous abortion

0%(n)

71.4(105/147)^{b, c}

73.2(120/164)^e

80.1(387/483)^f

85.2(413/485)

< 0.001^*

1%(n)

19.7(29/147)^c

18.3(30/164)^e

14.5(70/483)

12.2(59/485)

0.067

2%(n)

8.9(13/147)^c

8.5(14/164)^e

5.4(26/483)^f

2.6(13/485)

0.003^*

Endometrial thickness on the transformation day, mean(SD)(mm)

9.06 ± 1.53

9.11 ± 1.48

9.16 ± 1.44

9.27 ± 1.42

0.323