Characteristics of the study subjects (n = 45,065)
| Variables | Cases (n = 7,407), n (%) | Controls (n = 37,658), n (%) | ||
|---|---|---|---|---|
| Age at diagnosis or enrollment (y) | ||||
| 17-29 | 148 (2.0) | 868 (2.3) | ||
| 30-39 | 741 (10.0) | 3,974 (10.6) | ||
| 40-49 | 2,003 (27.0) | 10,177 (27.0) | ||
| 50-59 | 2,594 (35.0) | 13,054 (34.7) | ||
| 60+ | 1,921 (26.0) | 9,585 (25.4) | ||
| Parity | ||||
| 1 | 2,071 (28.0) | 8,653 (23.0) | ||
| 2 | 3,313 (44.7) | 16,498 (43.8) | ||
| 3 | 1,418 (19.1) | 8,430 (22.4) | ||
| 4 or more | 605 (8.2) | 4,077 (10.8) | ||
| Age at 1st childbirth (y) | ||||
| 14-19 | 1,350 (18.2) | 6,490 (17.2) | ||
| 20-24 | 3,158 (42.6) | 16,179 (43.0) | ||
| 25-29 | 2,011 (27.2) | 10,557 (28.0) | ||
| 30-34 | 673 (9.1) | 3,365 (9.0) | ||
| 35+ | 215 (2.9) | 1,067 (2.8) | ||
| Education level (y) | ||||
| <9 | 3,652 (49.3) | 18,086 (48.0) | ||
| ≥9 | 3,503 (47.3) | 18,536 (49.2) | ||
| Missing information | 252 (3.4) | 1,036 (2.8) | ||
| Area of residence | ||||
| Urban | 3,985 (53.8) | 20,775 (55.2) | ||
| Rural | 3,422 (46.2) | 16,883 (44.8) | ||
| Gender of offspring | ||||
| All girls | 2,007 (27.1) | 8,836 (23.5) | ||
| All boys | 2,103 (28.4) | 10,007 (26.6) | ||
| Mixed boys and girls | 3,297 (44.5) | 18,815 (50.0) | ||