Table 1 Demographic characteristics of women in the four groups

Number of patients, n (%)

17,504 (91.0)

835(4.3)

446(2.3)

454(2.4)

Maternal age, y

30.36 ± 4.15^a

32.97 ± 4.80

33.17 ± 4.79

33.83 ± 5.27

Body mass index, kg/m²

21.87 ± 2.97

22.35 ± 3.20*

21.75 ± 2.84*

21.85 ± 3.14

Baseline FSH, mIU/mL

7.33 ± 1.87

9.10 ± 3.51

8.53 ± 2.76

10.52 ± 4.78

Antral follicle count (AFC)

15.05 ± 6.56

7.64 ± 2.77*

3.31 ± 0.95*

3.18 ± 0.93

AMH level, ng/ml

6.04 ± 4.15

0.86 ± 0.24*

2.46 ± 1.41*

0.69 ± 0.30

Duration of infertility, years

3.38 ± 2.46

3.41 ± 2.93

3.67 ± 2.95

3.45 ± 3.15

Infertility diagnosis

Primary infertility, %

67.2^a

(11,767/17504)

59.6 (498/835)

57.8 (258/446)

58.1 (264/454)

Secondary infertility, %

32.8^a (5737/17504)

40.4 (337/835)

42.2 (188/446)

41.9

(190/454)

Infertility etiology, %

Male factor

23.9 (4176/17504)

15.6 (130/835)

12.8

(57/446)

14.1

(64/454)

Tubal factor

46.6 (8158/17504)

36.8 (307/835)

32.1 (143/446)

29.7

(135/454)

Ovulatory

9.6 (1675/17504)

0.2

(2/835)

0.9

(4/446)

0.4

(2/454)

Diminished ovarian reserve

4.8 (433/17504)

41.3(345/835)

47.5(212/446)

52.9

(240/454)

Unexplained/Other

15.2 (2662/17504)

6.1

(51/835)

6.7

(30/446)

2.9

(13/454)

Ovarian stimulation protocols

GnRH Antagonist, %

20.4^a

(3576/17504)

75.8*

(633/835)

92.8*

(414/446)

97.1

(441/454)

Long GnRH-a, %

29.5^a

(5170/17504)

13.9*(116/835)

2.7*(12/446)

0.2

(1/454)

GnRH-a ultra-long, %

50.1^a(8766/17504)

10.3*(86/835)

4.5*(20/446)

2.6(12/454)

Gn duration, days

10.49 ± 1.94

9.73 ± 1.67

9.55 ± 1.64

9.26 ± 2.01

Gonadotropin dose, IU

2311 ± 835^a

2921 ± 781

2799 ± 713

2813 ± 902

E2 on hCG, pg/mL

3137 ± 1900^a

1618 ± 930*

1980 ± 1105*

1288 ± 729

P on hCG day, ng/mL

0.92 ± 0.54^a

0.74 ± 0.39*

0.83 ± 0.44*

0.72 ± 0.49

No. of oocytes retrieved

13.65 ± 6.54^a

6.23 ± 3.63

6.94 ± 3.67

4.34 ± 2.59

No. of MII oocytes

11.87 ± 5.92^a

5.48 ± 3.27

6.20 ± 3.43

3.85 ± 2.43

Poor ovarian response, %

2.6^a (455/17504)

24.0* (200/835)

18.6*

(83/446)

43.0

(195/454)

Suboptimal ovarian response, %

25.9^a (4525/17504)

60.5 (505/835)

59.6

(266/446)

52.9

(240/454)

Oocyte maturation rate

0.87 ± 0.14^a

0.89 ± 0.17

0.90 ± 0.15

0.88 ± 0.22

The number of 2PN

8.18 ± 4.71

3.75 ± 2.70

4.27 ± 2.83

2.74 ± 2.14

Normal fertilization rate

0.64 ± 0.21

0.63 ± 0.28

0.65 ± 0.26

0.63 ± 0.32

Good-quality embryo rate on day 3

0.50 ± 0.27

0.49 ± 0.33

0.51 ± 0.35

0.49 ± 0.36

blastocyst formation rate

0.63 ± 0.29

0.56 ± 0.37

0.61 ± 0.35

0.46 ± 0.40

No. of available embryos

8.14 ± 4.78

3.75 ± 2.66

4.26 ± 2.76

2.78 ± 2.16

Available embryo rate

0.64 ± 0.22

0.63 ± 0.28

0.66 ± 0.28

0.64 ± 0.32

No. of embryos transferred

1.01 ± 0.78

1.06 ± 0.76

0.94 ± 0.76

0.88 ± 0.80

Endometrial thickness, mm

11.90 ± 2.64

11.02 ± 2.55

10.88 ± 2.49

10.84 ± 2.50

Cumulative live birth rate, %

57.8(10,120/17504)

37.5(313/835)

36.3(162/446)

28.2(128/454)

Live birth rate, %^b

33.8^a (5924/17483)

28.9 (241/834)

23.5

(105/445)

20.0 ^c

(91/454)

Live birth rate, %^c

48.2

(5924/12286)

39.2 (241/615)

34.5 (105/304)

32.6

(91/279)

Clinical pregnancy rate, %^b

39.1^a (6845/17504)

35.0 (292/835)

28.3

(126/446)

23.3^c

(106/454)

Clinical pregnancy rate, %^c

55.6a (6845/12307)

47.4 (292/616)

41.3 (126/305)

38.0

(106/279)