Table 1 Characteristics of participants included in the analysis

Age, median (IQR ^a), years

31.00 (26.00, 34.00)

32.00 (27.00, 35.00)

28.00 (25.00, 31.00)

0.005

Age groups, years

0.017

 18–24

14 (12.3)

8 (9.0)

6 (24.0)

 25–30

37 (32.5)

25 (28.1)

12 (48.0)

 31–35

43 (37.7)

38 (42.7)

5 (20.0)

 36–45

20 (17.5)

18 (20.2)

2 (8.0)

BMI ^b, median (IQR ^a), kg/m²

20.73 (19.30, 22.67)

20.82 (19.33, 22.59)

20.70 (19.29, 23.51)

0.88

BMI groups

0.294

 < 18.5

12 (10.5)

8 (9.0)

4 (16.0)

 18.5–23.9

86 (75.4)

70 (78.7)

16 (64.0)

 ≥ 24

16 (14.0)

11 (12.4)

5 (20.0)

Marital status

0.42

 Married

54 (47.4)

45 (50.6)

9 (36.0)

 Single

59 (51.8)

43 (48.3)

16 (64.0)

 Divorced

1 (0.9)

1 (1.1)

0 (0.0)

Educational attainment

0.599

 High school

4 (3.5)

4 (4.5)

0 (0.0)

 College

52 (45.6)

39 (43.8)

13 (52.0)

 Master’s or above

58 (50.9)

46 (51.7)

12 (48.0)

Occupation

0.069

 Unemployed

29 (25.4)

20 (22.5)

9 (36.0)

 Full-time worker

84 (73.7)

69 (77.5)

15 (60.0)

 Part-time worker

1 (0.9)

0 (0.0)

1 (4.0)

Duration of menstruation, median (IQR ^a), days

6.00 (5.00, 7.00)

6.00 (5.00, 7.00)

6.00 (5.00, 7.00)

0.319

Menarche, median (IQR ^a), years

13.00 (12.00, 14.00)

13.00 (12.00, 14.00)

13.00 (12.00, 14.00)

0.699

Smokers

3 (2.6)

3 (3.4)

0 (0.0)

1

Consume alcohol

27 (23.7)

24 (27.0)

3 (12.0)

0.197

Previous pregnancy

49 (43.0)

43 (48.3)

6 (24.0)

0.052

Previous childbirth

49 (43.0)

43 (48.3)

6 (24.0)

0.052

AMH ^c, median (IQR ^a), ng/ml

3.90 (2.13, 5.61)

3.53 (2.09, 5.25)

4.84 (3.24, 7.73)

0.062

AMH ^c groups

0.035

 < 0.7

7 (6.1)

4 (4.5)

3 (12.0)

 0.7–7.5

89 (78.1)

74 (83.1)

15 (60.0)

 > 7.5

18 (15.8)

11 (12.4)

7 (28.0)