Table 2.
Relative risk of endometrial cancer after a pregnancy compared with having one pregnancy less by pregnancy number and type, stratified by weeks of gestation
| Pregnancy No, type, and duration | Adjusted relative risk (95% CI)* |
|---|---|
| First pregnancy† | |
| Induced abortion (weeks): | |
| ≤5 | 0.66 (0.30 to 1.48) |
| 6-7 | 0.56 (0.43 to 0.73) |
| 8-9 | 0.54 (0.41 to 0.70) |
| 10-11 | 0.46 (0.29 to 0.71) |
| ≥12 | 0.59 (0.24 to 1.41) |
| Childbirth (weeks): | |
| ≤36 | 0.61 (0.44 to 0.85) |
| ≥37 | 0.49 (0.43 to 0.55) |
| Any subsequent† | |
| Induced abortion (weeks): | |
| ≤5 | 0.71 (0.49 to 1.02) |
| 6-7 | 0.75 (0.68 to 0.83) |
| 8-9 | 0.84 (0.76 to 0.92) |
| 10-11 | 0.93 (0.80 to 1.08) |
| ≥12 | 0.81 (0.51 to 1.28) |
| Childbirth (weeks): | |
| ≤36 | 0.87 (0.70 to 1.10) |
| ≥37 | 0.73 (0.69 to 0.78) |
*
Adjusted for age, period, educational attainment, marital status, urbanicity, and interaction between period and age, educational attainment, marital status, and urbanicity, respectively.