Table 1. Baseline characteristics of the 269 women included in the study.
| All women (N=269) | CYP1A2*1F A/A (N=136) | CYP1A2*1F any C (N=131) | |
|---|---|---|---|
| Median (inter quartile range) or % | |||
| Year of birth | 1970 (1965–1979) | 1970 (1965–1975) | 1970 (1964–1976) |
| Age at baseline (years) | 29 (24–34) | 29 (24–33) | 30 (24–36) |
| Age at menarche (years)a | 13 (12–13.4) | 13 (12–13) | 13 (12–14) |
| Age at first birth in parous women (years) | 24.5 (22–28) | 24 (23–27) | 25 (22–28) |
| Nulliparous (%) | 52 | 54 | 49 |
| Ever smoker (%)a | 42 | 41 | 42 |
| Current smoker (%)a | 23 | 24 | 22 |
| Hormonal contraceptive use, ever (%) | 92.5 | 93 | 92 |
| Current hormonal contraceptive use (%) | 42 | 48 | 36 |
| Daily coffee intake, cups (%) | |||
| None | (32.3) | (31.6) | (32.8) |
| <1.0 | (3.0) | (2.9) | (3.1) |
| 1.0–1.9 | (5.9) | (7.6) | (4.6) |
| 2.0–2.9 | (17.1) | (16.9) | (16.8) |
| 3.0–3.9 | (6.7) | (5.1) | (8.4) |
| 4.0–4.9 | (11.5) | (15.4) | (7.6) |
| 5.0–5.9 | (5.6) | (4.4) | (6.9) |
| 6+ | (17.8) | (16.2) | (19.8) |
| Height (cm)b | 168 (164–172) | 168 (164–173) | 168 (164–172) |
| Weight (kg)b | 64 (58–74) | 64 (58–75) | 65 (58–73) |
| BMI (kg/m2)b | 22.8 (20.9–25.6) | 22.7 (20.8–26.2) | 22.8 (20.9–24.9) |
| Waist-to-hip ratiob | 0.76 (0.73–0.80) | 0.77 (0.73–0.80) | 0.75 (0.73–0.80) |
| Total breast volume (ml)c | 756 (537–1101) | 711 (555–1167) | 777 (531–1040) |
BMI=body mass index.
a
One woman had not answered the question about age at menarche and the question about smoking.
b
The body measurements were taken 5–10 days before the predicted onset of the next menstrual period, that is during cycle days 18–23 in most women.
c
Total breast volumes were available for 255 women who were not currently breast-feeding or had undergone previous breast surgeries.