TABLE 1.

Characteristics of 21,506 Premenopausal Women According to Body Mass Index (kg/m²): the Black Women’s Health Study, 1997^*

	Body Mass Index
Characteristic	<20.0 (n = 1330)	20.0–24.9 (n = 7454)	25.0–29.9 (n = 6336)	30.0+ (n = 6386)
BMI (kg/m2); mean	18.9	22.7	27.3	36.4
BMI at age 18 yr (kg/m2); mean	17.8	19.8	21.5	25.4
Height (1995) (in); mean	65.6	65.1	65.1	64.9
Waist circumference (1995) (in); mean†	25.8	28.2	31.5	36.9
Hip circumference (1995) (in); mean†	34.2	37.0	40.1	45.2
Energy intake (1995) (kcal/d); mean‡	1540	1450	1522	1664
Age at menarche (yr); mean§	13.1	12.6	12.3	12.0
Age at first birth (yr); mean§	23.8	23.5	22.9	22.4
Time since last birth (yr); mean§	10.1	10.4	10.5	11.0
Age (yr); %
<30	45	32	23	23
30–39	43	45	45	44
40+	12	23	32	33
Parous; %	51	54	58	58
Geographic region of residence (1995); %
Northeast	30	28	28	29
West	21	21	18	15
Midwest	20	21	23	25
South	29	30	31	31
Education (1995) (yrs); %
≤ 12	11	10	14	17
13–16	66	65	65	65
17+	23	25	21	18
Papanicolaou smear since 1995; %	89	92	91	88
Oral contraceptive use; %
Current user	23	27	24	18
Former user	56	56	58	60
Cigarette smoking; %
Current smoker	17	13	14	15
Former smoker	9	12	14	16
Current alcohol intake (1+ drinks/wk); %	27	29	29	25
Vigorous physical activity; %
None	41	31	36	49
<5 h/wk	48	54	53	45
5+ h/wk	11	15	11	6

^*Data from 1997 (start of follow up) unless otherwise noted. Characteristics (with exception of age) are standardized to age distribution of women free of uterine leiomyomata at the start of follow up.

^†Limited to 17,876 women with complete data on waist and hip circumference.

^‡Limited to 20,020 women with complete data on energy intake derived from a self-administered 68-item Block food frequency questionnaire.

^§Limited to 12,022 parous women.