Table I.
Age-Standardized characteristics of premenopausal women according to category of total physical activity at baseline (1989): Nurses’ Health Study II, 1989
| Total physical activity (MET h/week) | ||||||
|---|---|---|---|---|---|---|
| Characteristic | <3 (n = 16,086) | 3 – <9 (n = 24,298) | 9 – <18 (n = 22,413) | 18 – <27 (n = 14,133) | 27 – <42 (n = 12,867) | ≥42 (n = 17,478) |
| Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | |
| Age, ya | 34.7 ± 4.5 | 34.4 ± 4.6 | 34.2 ± 4.6 | 34.1 ± 4.6 | 33.8 ± 4.6 | 33.2 ± 4.7 |
| Age at menarche, y | 12.4 (0.01) | 12.4 (0.01) | 12.4 (0.01) | 12.4 (0.01) | 12.4 (0.01) | 12.5 (0.01) |
| BMI at age 18, kg/mb | 21.4 (0.03) | 21.3 (0.02) | 21.3 (0.02) | 21.2 (0.03) | 21.2 (0.03) | 21.1 (0.03) |
| BMI, kg/mb | 25.2 (0.04) | 24.5 (0.03) | 24.0 (0.03) | 23.6 (0.04) | 23.3 (0.04) | 23.1 (0.04) |
| Pack-years of smokingb | 12.2 (0.10) | 11.6 (0.08) | 10.8 (0.09) | 10.7 (0.11) | 10.6 (0.11) | 10.5 (0.10) |
| Duration of oral contraceptive use (m)c | 52.5 (0.4) | 52.6 (0.3) | 53.1 (0.3) | 53.6 (0.4) | 53.7 (0.4) | 54.6 (0.4) |
| Alcohol intake (g/d) | 2.4 (0.05) | 2.7 (0.04) | 2.9 (0.04) | 3.2 (0.05) | 3.4 (0.05) | 3.7 (0.04) |
| Parity (pregnancies > 6 m)d | 2.1 (0.01) | 2.1 (0.01) | 2.1 (0.01) | 2.0 (0.01) | 2.0 (0.01) | 2.0 (0.01) |
| Breastfeeding duration (m)d | 12.0 (0.1) | 12.8 (0.1) | 13.2 (0.1) | 13.0 (0.1) | 12.9 (0.2) | 12.5 (0.1) |
| Dietary vitamin D intake (IU/d) | 235 (1.1) | 246 (0.9) | 255 (0.9) | 260 (1.1) | 263 (1.2) | 266 (1.1) |
| Vegetable protein intake (% of kcal) | 4.8 (0.01) | 4.9 (0.01) | 5.0 (0.01) | 5.1 (0.01) | 5.2 (0.01) | 5.2 (0.01) |
| % | % | % | % | % | % | |
| Oral contraceptive use | ||||||
| Past | 69.5 | 70.1 | 69.5 | 69.4 | 68.4 | 67.2 |
| Current | 13.0 | 12.6 | 13.6 | 13.8 | 14.2 | 15.5 |
| Nulliparous | 24.2 | 25.3 | 27.3 | 31.4 | 33.4 | 38.5 |
| Smoking status | ||||||
| Past | 21.3 | 21.6 | 23.2 | 24.0 | 24.5 | 25.0 |
| Current | 13.9 | 12.3 | 10.3 | 9.8 | 9.3 | 10.5 |
aFor age, values presented are unadjusted mean and standard deviation. All characteristics were calculated with the use of generalized linear models adjusted for the age of participants in 1989. All variables are significant at the P < 0.05 level.
bAmong ever-smokers.
cAmong ever users of oral contraceptives.
dAmong parous women.