Table 1.
Study Population Description
| Characteristic | Percentage of cohort | Number of women |
|---|---|---|
| Age, years | ||
| 18–29 | 29.2 | 1,570 |
| 30–34 | 46.3 | 2,490 |
| 35–45 | 24.5 | 1,316 |
| BMI, kg/m2 | ||
| <18.5 | 3.3 | 177 |
| 18.5–24.9 | 68.9 | 3,644 |
| 25–29.9 | 19 | 1,005 |
| 30–34.9 | 6.3 | 333 |
| >35 | 2.4 | 128 |
| Maximum educational level | ||
| Primary school | 0.8 | 36 |
| Secondary school | 10.4 | 450 |
| University degree | 68.8 | 2,971 |
| Trade/technical/vocational training | 9.0 | 388 |
| PhD | 11.0 | 473 |
| Average cycle length, days | ||
| 21–35 | 88.0 | 4,713 |
| <21 or >35 | 12.0 | 641 |
| Cycle length variability, standard deviation, days | ||
| <5 | 79.0 | 4,232 |
| ≥5 | 21.0 | 1,122 |
| Temperature logging frequency, % of days | ||
| 0–50 | 48.5 | 2,605 |
| 50–70 | 16.6 | 892 |
| 70–100 | 34.9 | 1,875 |
| Sex logging frequency, % of days | ||
| 0 | 18.1 | 973 |
| 0.1–10 | 37 | 1,989 |
| 10–20 | 27.4 | 1,471 |
| 20–100 | 17.5 | 943 |
| Gravidity 1 or higher, % | 27.8 | 1,255 |
Not all questions were mandatory and therefore response rate varied.
BMI, body mass index.