Table 5.

Relationship of Clomiphene and Gonadotropin Use to Breast Cancer Risk According to Selected Breast Cancer Risk Factors and Causes of Infertility

	Clomiphene (ever versus never use of clomiphene or gonadotropins)			Gonadotropins (ever versus never use of clomiphene or gonadotropins)
	# exposed cases	HR1	95% CI	# exposed cases	HR1	95% CI
Age at follow-up
<50 years	100	0.86	0.67–1.11	25	0.90	0.58–1.38
50–59 years	134	1.09	0.87–1.37	44	1.38	0.99–1.93
≥60 years	50	0.94	0.66–1.33	13	0.82	0.45–1.47
Reproductive status at first clinic visit
Gravid	170	1.11	0.91–1.35	46	1.10	0.80–1.51
Nulligravid	114	0.97	0.77–1.22	36	1.22	0.85–1.75
Reproductive status at follow-up
Gravid	200	1.02	0.85–1.23	54	1.04	0.78–1.39
Nulligravid	48	1.20	0.82–1.75	19	1.58	0.93–2.68
Unknown	36	1.04	0.70–1.57	9	1.12	0.55–2.27
Mother or sister with breast cancer
No	146	1.05	0.85–1.31	45	1.17	0.84–1.64
Yes	36	1.41	0.88–2.27	11	1.29	0.64–2.58
Unknown	102	0.92	0.72–1.17	26	0.95	0.63–1.44
Causes of infertility
Endometriosis	92	1.23	0.92–1.65	24	1.15	0.72–1.83
Anovulation	120	1.03	0.78–1.35	33	1.02	0.68–1.53
Tubal disease/pelvic adhesions	103	1.12	0.87–1.45	29	1.16	0.77–1.74
Cervical disorder	21	0.77	0.41–1.42	9	0.80	0.36–1.80
Uterine disease	31	1.02	0.64–1.62	10	1.25	0.62–2.51
Male factor	74	1.25	0.92–1.69	20	1.29	0.79–2.11

¹HRs adjusted for study site, calendar year of first infertility evaluation, gravidity at first clinic visit.