Table 1.

Cumulative evidence for reproductive history and exogenous exposures*

	BRCA1				BRCA2
	Breast cancer		Ovarian cancer		Breast cancer		Ovarian cancer
Factor	Grade†	Inference‡	Grade†	Inference‡	Grade†	Inference‡	Grade†	Inference‡	Studies included
Abortion	ACB	IE			BCB	IE			(18,20)
Later age at first live birth	ABA	PA(–)	ABB	PN	BCB	IE	BBB	PN	(18–20,23)
Alcohol consumption	ABB	PS(–)			BAA	PN			(32–34)
Breastfeeding	ABB	PS(–)	ABB	PS(–)	BBB	PN	BBB	PN	(18,20,24,25–27,62)
Coffee consumption	BBB	PN	BCC	IE	BCB	IE			(25,35,36)
Combined HRT* exposure	BCB	IE	BBB	PN			BBB	PN	(54,57,59)
Infertility treatment	ACB	IE			BCB	IE			(61)
Mammography	ABB	PN			BBB	PN			(37,38)
Late age at menopause	ACB	IE			BCB	IE			(28)
Medical radiation	ACB	IE							(39)
Late age at menarche	ABB	PS(–)	BCC	IE	BBB	PN	BCB	IE	(25,27–29)
Miscarriage	ABB	PN			BCB	IE			(18,20)
Oral contraceptive use	ABA	PS(+)	ABA	PS(–)	BAA	PS(+)	BBB	PS(–)	(18,22,25,43,45,58–60,68,70)
High parity	ACB	IE	ACB	IE	BBC	IE	BBB	PN	(18–20,23,25,27,30,31,59,60)
Smoking	ACB	IE	BCC	IE	BAB	PS(+)			(25,33,46–50)
Tamoxifen (contralateral breast cancer)	BBB	PS(–)	BCB	IE	BBB	PS(–)			(51–53,59,63)
Tubal ligation			ABB	PS(–)			BBB	PN	(56,58,60)
Weight change	BCB	IE			BCB	IE			(55)
X-ray	ACB	IE			BCB	IE			(33,40)

* HRT = hormone replacement therapy.

† For grade, first letter is for amount of evidence, second letter is for replication, and third letter is for bias.

‡ IE = insufficient evidence; PA = probable association; PN = probable or possible null association; PS = possible association. For probable and possible associations, (−) indicates a protective effect of the factor on cancer, whereas (+) indicates a risk effect on cancer.