From: Oral contraceptive use before first birth and risk of breast cancer: a case control study
Age at start of OC use (in years) | Cases | Controls | Crude | Adjusted* | |
---|---|---|---|---|---|
n | n | OR | OR | 95% CI | |
16–19 | 11 | 36 | 0.6 | 0.5 | (0.2, 1.6) |
20–24 | 77 | 140 | 0.9 | 0.9 | (0.5, 1.9) |
≥ 25† | 21 | 40 | 1 | 1 | |
Age missing | 5 | 6 | .. | .. |