. Author manuscript; available in PMC: 2014 Jul 1.

Published in final edited form as: Genet Epidemiol. 2013 May 14;37(5):504–511. doi: 10.1002/gepi.21730

Table I.

Characteristics of Study Sample by Case-Control and Menopausal Status, among Whites, WEB Study

Characteristics^*	Pre-menopausal (n=811)		Post-menopausal (n=1959)
Characteristics^*	Cases	Controls	Cases	Controls
N	279	532	726	1233
Age (years)	45.0 (4.6)^a	44.2 (4.6)^a	63.4 (8.4)	62.9 (8.9)
Education (years)	13.9 (2.3)^b	14.3 (2.2)^b	13.3 (2.6)^c	13.1 (2.3)^c
Body Mass Index	27.2 (6.9)	27.2 (6.6)	28.7 (5.9)	28.2 (6.0)
Age at menarche (years)	12.5 (1.5)	12.6 (1.6)	12.6 (1.6)^d	12.7 (1.7)^d
Age at menopause	/	/	48.4 (5.4)^e	47.6 (6.0)^e
Number of births	1.9 (1.3)	2.0 (1.3)	2.5 (1.7)^f	3.0 (1.9)^f
Percentage of women without child (%)	16.8	15.4	17.4^g	9.8^g
First-degree relative with breast cancer (% of Yes)	19.4^h	10.5^h	19.3ⁱ	13.8ⁱ
Previous benign breast disease (% of Yes)	37.3^j	22.2^j	33.5^k	23.4^k

Values for continuous variables are mean (SD); for categorical variables (race, first-degree relative with breast cancer, history of benign breast disease) values are for percentages among either the cases or controls. Two-sided comparisons of means between the cases and controls were computed by T-test for continuous and by χ square test for categorical variables.

The letters indicate statistical significant differences between comparison groups (P<0.05).