Table 1 Clinical characteristics and biochemical parameters of the participants (N = 114)

Age at enrollment, n (%)

 18–25 years

6 (12.76)

7 (10.45)

 25–29 years

7 (14.89)

15 (22.38)

 30–34 years

12 (25.53)

18 (26.86)

 35–39 years

14 (29.78)

17 (25.37)

 > 40 years

8 (17.02)

10 (14.93)

 Mean ± SD

33.30 ± 6.45

32.63 ± 5.87

0.47^a

BMI, n (%)

  < 18.5 kg/m²

6 (12.76)

13 (19.40)

 18.5–23.9 kg/m²

36 (76.60)

45 (67.16)

 24.0–30 kg/m²

5 (10.64)

9 (13.43)

 Mean ± SD

21.11 ± 2.25

20.88 ± 2.64

0.63^b

Annual household income, n (%)

  < 30,000 RMB yuan

7 (14.89)

1 (1.49)

 < 0.01^c

 30,000–100,000 RMB yuan

21 (44.68)

10(14.93)

  > 100,000 RMB yuan

19 (40.42)

56 (83.58)

Education, n (%)

 Elementary school

13 (27.65)

4 (5.97)

 < 0.01^c

 High school

15 (31.91)

6 (8.96)

 College

19 (40.43)

57 (85.07)

Biochemical parameters

 Mean ± SD (Range)

  FSH (IU/L)

72.32 ± 32.84 (27.86–149.47)

6.82 ± 2.26 (2.25–15.56)

 < 0.01^a

  LH (IU/L)

39.48 ± 16.25 (14.33–77.56)

4.10 ± 1.51 (1.13–8.08)

 < 0.01^b

  E2 (pmol/L)

188.61 ± 151.02 (43.31–755.46)

150.20 ± 74.37 (69.11–560.06)

0.37^a

  AMH (ng/mL)

0.02 ± 0.02 (0.01–0.08)

3.36 ± 2.37 (0.18–11.28)

 < 0.01^a

  Vitamin A (µg/L)

728 ± 176 (349–1162)

662 ± 113 (374–943)

0.13^b

  TC (mmol/L)

5.20 ± 1.07 (3.86–9.77)

4.31 ± 0.74 (2.76–6.87)

 < 0.01^b

  Vitamin A/TC

143.14 ± 35.86 (62.95–218.87)

157.56 ± 35.21 (84.04–256.16)

0.04^b