Table 3

Association between early menopause and exposure to tobacco smoke

Variable
% with early menopause and total number that answered
Crude OR
95% CI
Adj. OR a
95% CI


%
N

Lower
Upper

Lower
Upper

Number of cigarettes smoked daily
0
7.8
966
Ref.


Ref.


1–10
9.7
610
1.24
0.86
1.78
1.17
0.81
1.68
>10
12.1
514
1.54
1.08
2.21
1.48
1.03
2.13
Total smoking exposure b
Low exposure
7.2
334
Ref.


Ref.


Medium exposure
12.1
354
1.73
1.02
2.94
1.70
1.00
2.89
High exposure
13.2
364
1.82
1.08
3.06
1.79
1.06
3.02
Age when started daily smoking (current smokers. N = 514)
<20
14.9
235
Ref.


Ref.


20–24
14.0
164
0.97
0.55
1.73
0.95
0.52
1.73
>24
10.5
105
0.72
0.35
1.50
0.73
0.35
1.53
Age when started daily smoking (former smokers. N = 609)
<20
10.5
286
Ref.


Ref.


20–24
8.1
197
0.71
0.37
1.35
0.68
0.35
1.32
>24
6.4
110
0.58
0.25
1.37
0.59
0.25
1.40
Number of years before the age of menopause one stopped smoking (former smokers. N = 609)
Smoking at the time of menopause
16.9
195
Ref


Ref.


1–10
11.9
135
0.74
0.39
1.42
0.68
0.35
1.32
>10
2.3
256
0.14
0.06
0.34
0.13
0.05
0.33

a) Adjusted for educational level

b) Number of cigarettes per year × years smoked

Mikkelsen et al. BMC Public Health 2007 7:149   doi:10.1186/1471-2458-7-149