6. Barad 2005: first fracture and oral contraceptive use.

Oral contraceptive usea		Hazard ratio (95% CI)
Any OC useb	None	1.00
	Any	1.07 (1.01 to 1.15)
Years of OC usec	None	1.00
	< 5 years	1.09 (1.01 to 1.18)
	5 to 10 years	1.07 (0.96 to 1.20)
	> 10 years	1.02 (0.91 to 1.15)
Excluding women with prior fractured	No OC use	1.00
	< 5 years OC use	1.08 (0.99 to 1.18)
	> 5 years OC use	1.05 (0.96 to 1.16)

^aSample sizes overall: OC users 33,025; OC nonusers 47,922
 ^bAdjusted for baseline age (1‐year intervals), hormone therapy use and duration, follow‐up time, calcium intake (mg); use of corticosteroids, vitamin D, thiazide, thyroid hormone; age, race or ethnicity, smoking, alcohol use, exercise, body mass index, parity, irregular menses before menopause, hysterectomy, age at menopause, menopausal symptoms, prior fracture before age 55, length of OC use, age of last OC use, and age of first OC use.
 ^cModel adjusted as above, with duration of OC use in 5‐year intervals (excluding adjustment for duration of OC use as covariate)
 ^dBase model used excluding participants with prior fracture