Table 1.
Age-standardizeda characteristics of participants in the Nurses’ Health Study (NHS) in 1986 and NHSII in 1993 by WHR, BMI and study population.
| NHS | NHSII | |||||||
|---|---|---|---|---|---|---|---|---|
| WHR (n = 41,531) | BMI (n = 77,264) | WHR (n = 47,590) | BMI (n = 105,524) | |||||
| Quintile | 1 | 5 | 1 | 5 | 1 | 5 | 1 | 5 |
| Sample size | 9,248 | 7,234 | 12,019 | 11,180 | 9,980 | 9,321 | 22,284 | 17,604 |
| Means | ||||||||
| Age (years) | 50.7 | 55.3 | 51.2 | 52.8 | 38.2 | 38.5 | 37.2 | 39.0 |
| Age at menarche (years) | 12.5 | 12.4 | 12.8 | 12.1 | 12.4 | 12.3 | 12.8 | 11.9 |
| Parity (among parous women) | 3.0 | 3.3 | 3.0 | 3.3 | 2.2 | 2.2 | 2.2 | 2.2 |
| Duration of oral contraceptive use (mo) | 25.1 | 22.2 | 26.8 | 21.0 | 51.0 | 46.2 | 45.6 | 42.3 |
| Current body mass index (kg/m2) | 22.7 | 27.6 | 19.9 | 34.4 | 22.4 | 27.7 | 19.8 | 35.5 |
| Current hip circumference (inches) | 39.1 | 40.6 | 36.2 | 46.5 | 38.7 | 41.1 | 36.0 | 47.6 |
| Current waist circumference (inches) | 27.5 | 36.1 | 27.2 | 38.4 | 26.9 | 36.8 | 27.1 | 40.0 |
| Height (meters) | 1.6 | 1.6 | 1.6 | 1.6 | 1.7 | 1.7 | 1.7 | 1.6 |
| Caffeine intake (mg/day) | 292.0 | 267.5 | 297.5 | 253.6 | 247.0 | 227.0 | 228.4 | 242.0 |
| Percentages | ||||||||
| Parous | 92.2 | 93.3 | 91.7 | 92.6 | 72.3 | 76.7 | 72.0 | 72.0 |
| Premenopausal | 36.5 | 34.7 | 38.0 | 37.8 | 97.7 | 97.5 | 92.3 | 92.1 |
| Postmenopausal | 63.4 | 65.2 | 61.0 | 61.2 | 1.2 | 1.4 | 1.0 | 1.0 |
| Family history of ovarian cancerc | 2.8 | 2.7 | 2.2 | 2.9 | 1.9 | 2.1 | 1.3 | 2.0 |
| History of tubal ligation | 16.6 | 16.3 | 16.8 | 17.7 | 20.0 | 22.8 | 17.9 | 23.3 |
| Current postmenopausal hormone user (among postmenopausal women) | 24.2 | 13.7 | 22.0 | 10.0 | 75.9 | 59.5 | 65.0 | 50.3 |
a
All factors except age were age-standardized in five-year intervals for each cohort.
b
WHR = waist to hip ratio; BMI = body mass index.
c
Mother or sister had ovarian cancer according to participant’s response on questionnaire; family history was evaluated using data from 1992 for NHS and 1993 for NHS II because it was not available in previous cycles.