Table I.
Baseline characteristics of 1651 women according to female BMI and height-adjusted waist circumferencea
| Characteristic | BMI (kg/m2) |
Waist circumference (cm) |
||||||
|---|---|---|---|---|---|---|---|---|
| <20 | 20–24 | 25–29 | ≥30 | <74 | 74–79 | 80–86 | ≥87 | |
| No. of women | 231 | 920 | 300 | 200 | 477 | 331 | 358 | 485 |
| Age, years (mean) | 28.2 | 28.8 | 28.6 | 28.3 | 28.2 | 28.7 | 28.9 | 28.9 |
| Partner's age, years (mean) | 31.0 | 31.0 | 31.4 | 31.1 | 31.0 | 31.1 | 31.0 | 31.2 |
| Age at menarche, years (mean) | 13.4 | 13.1 | 12.7 | 12.5 | 13.3 | 13.0 | 12.9 | 12.7 |
| Irregular cycles, yes (%) | 32.7 | 24.2 | 21.7 | 20.0 | 29.2 | 27.0 | 22.9 | 18.8 |
| Cycle length among regular cyclers, days (mean) | 28.7 | 28.8 | 29.0 | 28.8 | 28.8 | 28.8 | 28.8 | 28.8 |
| Height, cm (mean) | 170.2 | 169.0 | 169.0 | 168.4 | 169.7 | 169.1 | 168.7 | 168.8 |
| BMI, kg/m2 (mean) | 19.0 | 22.3 | 26.9 | 34.5 | 20.9 | 22.3 | 23.8 | 29.0 |
| BMI at age 17, kg/m2 (mean) | 18.5 | 20.3 | 22.7 | 25.8 | 19.9 | 20.1 | 21.1 | 23.3 |
| BMI of male partner, kg/m2 (mean) | 24.1 | 24.9 | 25.8 | 27.5 | 24.3 | 25.3 | 25.0 | 26.4 |
| Weight change since age 17, kg (mean) | 1.4 | 5.7 | 12.1 | 24.8 | 3.1 | 6.3 | 7.9 | 16.2 |
| Waist circumference, cm (mean) | 70.7 | 78.4 | 88.2 | 102.7 | 69.0 | 77.2 | 83.4 | 97.3 |
| WHR (mean) | 0.79 | 0.81 | 0.84 | 0.87 | 0.74 | 0.81 | 0.83 | 0.89 |
| Physical activity, MET h/week (mean) | 25.3 | 26.5 | 22.4 | 18.2 | 26.7 | 26.7 | 25.7 | 20.4 |
| Higher education ≥5 years | 26.5 | 28.8 | 16.3 | 11.7 | 32.7 | 28.8 | 21.3 | 15.1 |
| Parous, ever had live birth (%) | 33.5 | 31.0 | 42.4 | 44.2 | 27.7 | 32.4 | 36.6 | 42.6 |
| Pack-years of ever smoking (mean) | 1.3 | 2.0 | 2.6 | 2.3 | 1.3 | 1.9 | 2.2 | 2.8 |
| Mother smoked during pregnancy, yes (%) | 26.9 | 32.1 | 41.4 | 47.3 | 29.4 | 31.7 | 36.9 | 41.2 |
| Alcohol intake (current), drinks/week (mean) | 3.4 | 3.6 | 3.1 | 2.8 | 4.0 | 3.1 | 3.3 | 3.1 |
| Time in steady relationship, years (mean) | 5.0 | 4.9 | 5.5 | 5.6 | 4.9 | 4.5 | 5.1 | 5.6 |
| Frequency of intercourse, ≥4 times/week (%) | 23.6 | 19.0 | 15.6 | 14.4 | 20.5 | 22.6 | 15.0 | 15.9 |
| Last method of contraception used (%) | ||||||||
| Barrier methods | 26.7 | 26.5 | 32.0 | 31.2 | 24.6 | 26.2 | 30.5 | 31.2 |
| Oral contraceptives | 56.8 | 62.4 | 57.8 | 57.9 | 59.3 | 62.9 | 58.1 | 60.7 |
| Other hormonal contraception | 2.2 | 0.8 | 1.4 | 0.9 | 1.9 | 2.2 | 0.3 | 0.2 |
| Withdrawal/rhythm/charting/other | 14.4 | 10.3 | 8.8 | 10.0 | 14.3 | 8.7 | 11.1 | 7.9 |
| Hypertension, yes (%) | 1.8 | 4.4 | 6.5 | 8.2 | 3.2 | 5.9 | 3.5 | 6.7 |
| Diabetes, yes (%) | 0.0 | 0.2 | 1.0 | 2.8 | 0.0 | 0.0 | 0.4 | 1.7 |
| Attempt time before study entry, cycles (%) | ||||||||
| 0–1 | 54.6 | 54.7 | 56.2 | 50.1 | 54.4 | 53.8 | 54.0 | 55.1 |
| 2–3 | 28.4 | 25.6 | 21.8 | 28.2 | 25.2 | 26.9 | 25.5 | 24.9 |
| 4–6 | 16.9 | 19.7 | 22.0 | 21.7 | 20.3 | 19.2 | 20.5 | 20.0 |
aCharacteristics are presented as means and proportions within categories of each anthropometric variable and are age-standardized to cohort at baseline.