Table I.
Age-standardized characteristics of the study population of premenopausal nurses in 1989 by BMI status, Nurses’ Health Study II, 1989–2011a. Data are mean (SD) or percent.
| Characteristic | BMI | ||||||
|---|---|---|---|---|---|---|---|
| <18.5 (n = 2650) | 18.5–22.4 (n = 35 539) | 22.5–25.0 (n = 17 581) | 25.0–27.4 (n = 9745) | 27.5–29.9 (n = 4413) | 30.0–34.9 (n = 5145) | ≥35.0 (n = 3237) | |
| Age | 33.3 (4.6) | 34.3 (4.6) | 35.0 (4.5) | 35.3 (4.5) | 35.6 (4.4) | 35.8 (4.4) | 36.0 (4.2) |
| Physical activity, 1989 (MET*h/week) | 29.3 (45.2) | 27.2 (38.5) | 24.0 (34.1) | 21.6 (31.8) | 19.7 (28.2) | 19.3 (30.4) | 15.0 (25.1) |
| Cigarette smoking (total pack-years)b | 11.6 (8.8) | 10.7 (7.9) | 11.5 (8.0) | 11.9 (8.2) | 12.2 (8.4) | 12.3 (8.4) | 12.8 (8.7) |
| Alcohol consumption (gm/day) | 3.0 (6.1) | 3.4 (5.8) | 3.2 (5.9) | 2.8 (5.8) | 2.4 (5.2) | 2.1 (5.5) | 1.7 (4.5) |
| Oral contraceptive use (total duration, months) | 42.2 (46.0) | 44.8 (45.4) | 45.5 (45.8) | 43.8 (45.1) | 42.5 (45.0) | 41.2 (43.2) | 37.8 (43.3) |
| Parityc | 2.0 (0.9) | 2.1 (0.9) | 2.1 (0.9) | 2.1 (0.9) | 2.1 (1.0) | 2.1 (0.9) | 2.0 (0.9) |
| Age at menarche | 13.1 (1.5) | 12.6 (1.4) | 12.4 (1.4) | 12.2 (1.4) | 12.1 (1.4) | 11.9 (1.4) | 11.8 (1.4) |
| Breastfeeding (total duration, months)c | 13.4 (14.0) | 14.0 (13.6) | 13.2 (13.5) | 12.7 (13.2) | 11.8 (13.1) | 11.2 (12.6) | 9.6 (11.8) |
| % | % | % | % | % | % | % | |
| Race/ethnicity | |||||||
| White, non-Hispanic | 92.8 | 94.7 | 93.9 | 93.6 | 93.5 | 94.0 | 94.0 |
| Cigarette smoking status | |||||||
| Never | 68.7 | 66.2 | 64.3 | 64.6 | 65.8 | 65.5 | 67.2 |
| Past | 16.2 | 21.9 | 23.0 | 22.3 | 21.6 | 21.5 | 21.0 |
| Current | 15.2 | 11.9 | 12.8 | 13.1 | 12.6 | 12.9 | 11.7 |
| Oral contraceptive use status | |||||||
| Never | 19.4 | 16.4 | 16.4 | 17.8 | 18.7 | 19.8 | 24.9 |
| Past | 68.5 | 70.3 | 71.1 | 71.1 | 70.3 | 70.6 | 67.4 |
| Current | 12.1 | 13.2 | 12.5 | 11.1 | 11.1 | 9.7 | 7.7 |
aAll characteristics except age are standardized to the age distribution of study population in 1989. Values are means (standard deviation [SD]) or percentages. MET, metabolic equivalent tasks; BMI, body mass index.
bAmong smokers.
cAmong parous women.