Table 1.
Characteristics of 40 318 women 32 to 51 years of age in 1997 according to categories of average lifetime total activity, Nurses' Health Study II
| MET-h/wk (median) | ||||||
|---|---|---|---|---|---|---|
| Characteristic | <21 (14.5) | 21–29.9 (25.5) | 30–38.9 (34.3) | 39–53.9 (45.4) | >= 54 (68.2) | p |
| No. of participants | 10050 | 7759 | 6940 | 7647 | 7922 | |
| Age, y | 43.0 | 42.3 | 41.7 | 41.3 | 41.1 | <.0001 |
| Mother or sister with breast cancer, % | 7.9 | 7.8 | 7.8 | 7.9 | 7.5 | 0.73 |
| Current oral contraceptive user, % | 8.9 | 9.5 | 9.6 | 9.7 | 9.8 | 0.38 |
| Nulliparous, % | 17.4 | 17.7 | 18.0 | 19.5 | 22.3 | <.0001 |
| Parity | 2.3 | 2.34 | 2.3 | 2.3 | 2.3 | 0.002 |
| Age at first birth | 26.4 | 26.67 | 26.7 | 26.8 | 26.7 | <.0001 |
| Height, inches | 64.8 | 64.9 | 64.9 | 65.0 | 65.1 | <.0001 |
| Birthweight, GE 8.5 lbs, % | 11.6 | 12.3 | 11.6 | 12.1 | 12.1 | 0.06 |
| Overweight during ages 5 and 10, % | 7.1 | 6.6 | 6.4 | 5.7 | 5.6 | <.0001 |
| BMI at age 18, kg/m2 | 21.7 | 21.4 | 21.3 | 21.2 | 21.1 | <.0001 |
| Current BMI, kg/m2 | 27.2 | 26.3 | 25.9 | 25.9 | 25.5 | <.0001 |
| Alcohol intake GE 10 g/d, % | 6.6 | 9.1 | 8.8 | 10.3 | 11.0 | <.0001 |
| Current smoker, % | 8.9 | 9.2 | 9.4 | 9.3 | 11.0 | <.0001 |
| Age at menarche, <12 y, % | 26.1 | 23.1 | 23.7 | 22.6 | 23.8 | 0.65 |
| Television watching, h/wk | 8.7 | 8.3 | 8.3 | 8.4 | 8.6 | 0.20 |