Characteristics |
|
FOR |
95% CI |
|
FOR |
95% CI |
Age, years (women) (%)b |
Age, years
(women) (%)b |
Age, years (women)
(%)b |
Age, years (women)
(%)b |
Age, years (women)
(%)b |
Age, years (women)
(%)b |
Age, years (women)
(%)b |
20–24 |
15.5 |
ref |
ref |
|
ref |
ref |
25–29 |
14.6 |
0.89 |
0.84–0.95 |
|
0.82 |
0.74–0.92 |
30–34 |
16.7 |
0.92 |
0.83–1.02 |
|
0.85 |
0.71–1.01 |
35–39 |
35.5 |
0.39 |
0.34–0.45 |
|
0.44 |
0.36–0.55 |
≥40 |
18.0 |
0.67 |
0.48–0.95 |
|
0.40 |
0.24–0.69 |
P value
|
|
<.001 |
<.001 |
|
<.001 |
<.001 |
Education (women) (%) |
Education (women) (%) |
Education (women) (%) |
Education (women) (%) |
Education (women) (%) |
Education (women) (%) |
Education (women) (%) |
Primary school and below |
24.3 |
ref |
ref |
|
ref |
ref |
Middle school |
17.5 |
1.25 |
1.12–1.41 |
|
1.02 |
0.87–1.20 |
High school |
15.8 |
1.29 |
1.13–1.47 |
|
1.12 |
0.92–1.36 |
College and beyond |
14.8 |
1.25 |
1.10–1.43 |
|
1.31 |
1.04–1.64 |
P value
|
|
.001 |
.001 |
|
.036 |
.036 |
Employment (women) (%) |
Employment (women) (%) |
Employment (women) (%) |
Employment (women) (%) |
Employment (women) (%) |
Employment (women) (%) |
Employment (women) (%) |
Employmentc
|
19.0 |
ref |
ref |
|
ref |
ref |
Unemployment |
14.2 |
1.57 |
1.48–1.65 |
|
1.60 |
1.48–1.73 |
P value
|
|
<.001 |
<.001 |
|
<.001 |
<.001 |
Annual household income, yuan (%) |
Annual household
income, yuan (%) |
Annual household income, yuan (%) |
Annual household income, yuan (%) |
Annual household
income, yuan (%) |
Annual household income, yuan (%) |
Annual household income, yuan (%) |
<10,000 |
16.7 |
ref |
ref |
|
ref |
ref |
10,000–19,999 |
16.9 |
0.95 |
0.89–1.01 |
|
0.97 |
0.89–1.06 |
>20,000 |
19.4 |
0.79 |
0.73–0.85 |
|
0.75 |
0.67–0.84 |
P value
|
|
<.001 |
<.001 |
|
<.001 |
<.001 |
Age, years (men) (%)b |
Age, years
(men) (%)b |
Age, years (men)
(%)b |
Age, years (men)
(%)b |
Age, years (men)
(%)b |
Age, years (men)
(%)b |
Age, years (men)
(%)b |
20–24 |
15.3 |
ref |
ref |
|
ref |
ref |
25–29 |
14.5 |
0.95 |
0.88–1.03 |
|
0.93 |
0.84–1.04 |
30–34 |
14.9 |
1.00 |
0.91–1.10 |
|
0.85 |
0.73–0.99 |
35–39 |
32.0 |
0.50 |
0.44–0.56 |
|
0.55 |
0.46–0.66 |
≥40 |
19.4 |
0.67 |
0.53–0.83 |
|
0.76 |
0.54–1.07 |
P value
|
|
<.001 |
<.001 |
|
<.001 |
<.001 |
Education (men) (%) |
Education (men) (%) |
Education (men) (%) |
Education (men) (%) |
Education (men) (%) |
Education (men) (%) |
Education (men) (%) |
Primary school and below |
24.0 |
ref |
ref |
|
ref |
ref |
Middle school |
17.5 |
1.31 |
1.15–1.50 |
|
1.05 |
0.87–1.27 |
High school |
15.7 |
1.42 |
1.23–1.64 |
|
1.24 |
1.01–1.53 |
College and beyond |
15.3 |
1.31 |
1.13–1.52 |
|
1.15 |
0.90–1.46 |
P value
|
|
<.001 |
<.001 |
|
.034 |
.034 |
Toxic exposure (men)d |
Toxic
exposure (men)d |
Toxic exposure
(men)d |
Toxic exposure
(men)d |
Toxic exposure
(men)d |
Toxic exposure
(men)d |
Toxic exposure
(men)d |
No |
17.1 |
ref |
ref |
|
ref |
ref |
Yes |
20.9 |
0.73 |
0.62–0.85 |
|
0.67 |
0.54–0.84 |
P value
|
|
<.001 |
<.001 |
|
<.001 |
<.001 |
Duration of cohabitation, yearse |
Duration of cohabitation, yearse |
1.00 |
0.99–1.00 |
|
1.06 |
1.05–1.07 |
Menstrual cycle interval (day) |
Menstrual cycle
interval (day) |
Menstrual cycle interval (day) |
Menstrual cycle interval (day) |
Menstrual cycle
interval (day) |
Menstrual cycle interval (day) |
Menstrual cycle interval (day) |
≤23 |
16.0 |
0.81 |
0.73–0.90 |
|
0.88 |
0.75–1.03 |
24–35 |
18.0 |
ref |
ref |
|
ref |
ref |
>35 |
32.1 |
0.42 |
0.36–0.50 |
|
0.49 |
0.40–0.61 |
P value
|
|
<.001 |
<.001 |
|
<.001 |
<.001 |
History of abnormal pregnancy |
History of abnormal
pregnancy |
History of abnormal pregnancy |
History of
abnormal pregnancy |
History of abnormal pregnancy |
History of abnormal pregnancy |
History of abnormal
pregnancy |
No |
16.8 |
ref |
ref |
|
ref |
ref |
Yes |
20.7 |
0.77 |
0.71–0.84 |
|
0.83 |
0.74–0.94 |
P value
|
|
<.001 |
<.001 |
|
.003 |
.003 |
Parity |
Parity |
Parity |
Parity |
Parity |
Parity |
Parity |
Nullipara |
17.7 |
ref |
ref |
|
ref |
ref |
Multipara |
16.1 |
1.08 |
1.02–1.14 |
|
1.13 |
1.02–1.25 |
P value
|
|
.010 |
.010 |
|
.022 |
.022 |