Table 1 Baseline characteristics of the China Kadoorie Biobank female never-smokers by menopausal status
|  | Pre/perimenopausal (n = 138,668) | Postmenopausal (n = 143,890) | Total (n = 282,558) |
|---|---|---|---|
Age, years – median (IQR) | 42.2 (38.7—46.5) | 57.9 (53.6—64.3) | 50.5 (42.4–58.1) |
Married | 95.8% | 84.0% | 89.8% |
Rural resident | 58.3% | 52.1% | 55.1% |
Housewives | 7.8% | 23.1% | 15.6% |
Have no formal schooling | 13.4% | 36.0% | 24.9% |
Weight, kg – mean ± SD | 155.7 ± 5.7 | 152.9 ± 5.8 | 154.3 ± 5.9 |
Height, cm – mean ± SD | 57.4 ± 8.9 | 56.2.7 ± 9.8 | 56.8 ± 9.4 |
Physical activity, (METs-h/d)a – median (IQR) | 22.1 (14.0—33.7) | 13.4 (8.8—22.0) | 16.9 (10.7–28.6) |
Ever-alcohol drinker | 39.8% | 30.7% | 35.2% |
ETS exposure, daily/almost dailya | 46.6% | 37.3% | 41.9% |
Cooking fuel, clean energyb | 44.3% | 46.0% | 45.2% |
Heating fuel, clean energyb | 20.8% | 19.1% | 19.9% |
Age at menarche, years – mean ± SD | 14.9 ± 1.7 | 15.9 ± 2.0 | 15.4 ± 1.9 |
No of pregnancies – median (IQR) | 2 (2 -3) | 4 (3 -5) | 3 (2—4) |
Parity – median (IQR) | 1 (1—2) | 3 (2—4) | 2 (1—3) |
Age at first live birth, years – median (IQR) | 24 (22—25) | 23 (20—25) | 23 (21—25) |
Ever breastfed | 96.6% | 97.9% | 97.3% |
Breastfeeding per child, months – median (IQR) | 12 (10—18) | 12 (12—19) | 12 (11—18) |
Ever-oral contraceptive use | 9.7% | 10.1% | 9.9% |
Duration of OC use, years, median (IQR) | 2 (1—4) | 2 (1—5) | 2 (1—4) |
OC use starting age, years, median (IQR) | 25 (23—28) | 27 (25—30) | 26 (24—29) |
Age at menopause, years – median (IQR) | - | 49 (46—51) | 49 (46—51) |
Reproductive period, years – median (IQR) | - | 33 (30—35) | 33 (30—35) |
Had oophorectomy | 0.8% | 2.1% | 1.5% |
Had hysterectomy | 0.3% | 7.3% | 3.9% |
Family history of cancer | 15.5% | 18.0% | 16.8% |
Poor self-rated health | 8.3% | 13.0% | 10.7% |
Personal history of lung diseasec | 4.5% | 9.3% | 6.9% |