Table 1 Baseline characteristics of CKB women according to the menopausal status and age at natural menopause
Characteristics | Overall | Menopausal status | Age at menopause | ||||||
|---|---|---|---|---|---|---|---|---|---|
Pre- | Peri- | Post- | < 40 | 40–44 | 45–49 | 50–53 | ≧ 54 | ||
No. of women | 281,319 | 125,494 | 14,036 | 141,789 | 5,890 | 16,523 | 58,998 | 49,346 | 11,032 |
Mean age at baseline, year | 50.9 | 41.9 | 49.7 | 59.1 | 56.0 | 58.1 | 58.7 | 59.5 | 62.3 |
Birth cohorts, % | |||||||||
1920s–1930s | 9.5 | 0.03 | 0.06 | 18.7 | 22.0 | 21.1 | 18.2 | 17.1 | 23.2 |
1940s | 19.5 | 0.1 | 1.2 | 38.4 | 25.6 | 31.9 | 35.3 | 40.7 | 61.3 |
1950s–1970s | 71.0 | 99.9 | 98.8 | 42.9 | 52.4 | 47.0 | 46.5 | 42.2 | 15.5 |
Urban resident, % | 43.5 | 41.0 | 48.6 | 45.2 | 41.7 | 38.4 | 43.2 | 49.2 | 50.0 |
No formal school, % | 25.0 | 11.7 | 25.4 | 36.7 | 37.9 | 38.1 | 37.8 | 34.3 | 38.1 |
Lifestyle factors and anthropometric measurements, % or mean | |||||||||
Current regular smoker | 2.3 | 0.9 | 1.3 | 3.6 | 4.0 | 4.4 | 3.8 | 3.2 | 3.3 |
Current regular drinker | 3.6 | 3.6 | 4.0 | 3.5 | 4.0 | 3.8 | 3.5 | 3.5 | 3.4 |
Body mass index, kg/m2 | |||||||||
Overweight (24.0–27.9) | 33.0 | 31.5 | 38.1 | 33.9 | 32.6 | 32.1 | 33.0 | 35.1 | 36.8 |
Obesity (≧ 28.0) | 11.1 | 9.2 | 13.2 | 12.6 | 11.9 | 11.0 | 11.9 | 13.4 | 15.7 |
Waist circumference, cm | 78.7 | 77.0 | 79.4 | 80.1 | 79.4 | 79.3 | 79.7 | 80.5 | 81.5 |
Physical activity, MET, h/d | 20.8 | 24.8 | 21.8 | 17.2 | 18.8 | 18.0 | 17.5 | 16.7 | 15.8 |
Reproductive factors, % or mean | |||||||||
Age at menarche, year | 15.4 | 14.9 | 15.4 | 15.9 | 15.7 | 15.7 | 15.9 | 16.0 | 16.3 |
Nulliparous | 1.3 | 1.5 | 0.9 | 1.3 | 4.8 | 1.5 | 1.2 | 0.9 | 0.8 |
Oral contraceptive pill used | 9.5 | 8.7 | 13.9 | 9.8 | 7.3 | 8.5 | 9.9 | 10.6 | 9.7 |
No. of live births†| 2.2 | 1.6 | 1.7 | 2.8 | 2.6 | 2.9 | 2.8 | 2.7 | 3.2 |
Age at first birth, year†| 23.4 | 23.7 | 24.3 | 23.0 | 22.7 | 22.8 | 23.0 | 23.2 | 22.7 |
Never breastfed†| 2.8 | 3.6 | 3.2 | 2.2 | 3.5 | 2.6 | 2.1 | 2.0 | 1.7 |
Breastfeeding per child, month†| 14.3 | 13.4 | 14.2 | 15.0 | 14.8 | 15.1 | 15.2 | 14.7 | 15.2 |