Table 1 Demographic characteristics of participants

Age (y)

28.9 ± 3.0

35.2 ± 3.3

36.1 ± 3.2

< 0.001

BMI (kg/m²)

21.7 ± 1.9

21.9 ± 2.4

22.9 ± 3.9

0.43

Smoking (n)

0/20 (0%)

0/14 (0%)

3/25 (12.0%)

0.12^a

Cycle length (d)

29.4 ± 1.7

29.1 ± 2.0

29.8 ± 4.8

0.89

Abnormal karyotype (n)

0/20 (0%)

0/14 (0%)

0/25 (0%)

NA^a

Progesterone level (nmol/L)

–

62.4 ± 33.5

47.3 ± 20.9

0.31^b

 0

0/20 (0%)

10/14 (71.4%)

0/25 (0%)

< 0.001

 1

12/20 (60.0%)

3/14 (21.4%)

0/25 (0%)

< 0.001

  ≥ 2

8/20 (40.0%)

1/14 (7.1%)

25/25 (100%)

< 0.001

 0

0/20 (0%)

13/14 (92.9%)

23/25 (92.0%)

< 0.001

 1

14/20 (70.0%)

1/14 (7.1%)

2/25 (8.0%)

< 0.001

  ≥ 2

6/20 (30.0%)

0/14 (0%)

0/25 (0%)

< 0.001

 0

20/20 (100%)

10/14 (71.4%)

0/25 (0%)

< 0.001

 1

0/20 (0%)

3/14 (21.4%)

0/25 (0%)

< 0.001

 2

0/20 (0%)

1/14 (7.1%)

0/25(0%)

< 0.001

  ≥ 3

0/20 (0%)

0/14 (0%)

25/25 (100%)

< 0.001