Patient	Oral contraceptive use	OR (95% CI)
Nulliparous	Any	1.24 (0.92 to 1.67)
Nulliparous	Four or more years' duration	1.29 (0.85 to 1.96)
Parous	Any	1.29 (1.20 to 1.40)
Parous	Before first full-term pregnancy	1.44 (1.28 to 1.62)
Parous	After first full-term pregnancy	1.15 (1.06 to 1.26)
Parous	Four or more years' duration before first full-term pregnancy	1.52 (1.26 to 1.82)