| Total | Ever pregnant, % | Parous women (number of full-term pregnancy/age at first full-term pregnancy, yrs), % | ||||
---|---|---|---|---|---|---|---|
 |  | No | Yes | < 3/< 25 | < 3/≥ 25 | ≥ 3/< 25 | ≥ 3/≥ 25 |
 |  | (n = 8,937) | (n = 43,527) | (n = 8,034) | (n = 14,825) | (n = 10,851) | (n = 7,372) |
Race | Â | Â | Â | Â | Â | Â | Â |
   White | 46,624 | 16.8 | 83.2 | 19.8 | 34.4 | 28.2 | 17.7 |
   African-American | 1,622 | 11.1 | 88.9 | 25.9 | 34.6 | 28.3 | 11.2 |
   Others | 4,218 | 17.2 | 82.8 | 17.7 | 36.0 | 27.9 | 18.4 |
First-degree family history of breast cancer | Â | Â | Â | Â | Â | Â | Â |
   No | 43,489 | 16.6 | 83.4 | 19.8 | 34.5 | 28.3 | 17.3 |
   Yes | 7,132 | 16.8 | 83.2 | 19.2 | 34.5 | 27.0 | 19.3 |
   Unknown | 1,843 | 17.8 | 82.2 | 20.8 | 35.7 | 27.7 | 15.9 |
Age at menarche, years | Â | Â | Â | Â | Â | Â | Â |
   < 13 | 26,220 | 16.9 | 83.1 | 20.6 | 34.3 | 28.7 | 16.4 |
   ≥ 13 | 26,244 | 16.4 | 83.6 | 19.0 | 34.8 | 27.6 | 18.7 |
BMI, kg/m2 | Â | Â | Â | Â | Â | Â | Â |
   < 25 | 27,583 | 16.9 | 83.1 | 20.4 | 35.8 | 26.6 | 17.2 |
   25 to 29.9 | 14,354 | 15.8 | 84.2 | 19.1 | 32.6 | 30.0 | 18.3 |
   ≥ 30 | 7,783 | 17.5 | 82.5 | 19.1 | 33.4 | 30.6 | 16.9 |
   Unknown | 2,744 | 16.0 | 84.0 | 18.7 | 35.6 | 26.7 | 19.0 |
Menopausal HT use | Â | Â | Â | Â | Â | Â | Â |
   Never | 10,945 | 20.4 | 79.6 | 16.0 | 35.5 | 27.3 | 21.2 |
   E only | 15,676 | 15.6 | 84.4 | 21.8 | 31.2 | 30.4 | 16.7 |
   E plus P only | 14,959 | 15.8 | 84.2 | 19.8 | 37.7 | 25.8 | 16.7 |
   Mixed use | 7,169 | 15.7 | 84.3 | 21.1 | 32.7 | 30.3 | 15.9 |
   Unknown type of HT | 3,715 | 15.2 | 84.8 | 19.8 | 35.7 | 26.7 | 17.8 |
Duration of breastfeeding for parous women, months | Â | Â | Â | Â | Â | Â | Â |
   Never | 12,628 | - | - | 25.0 | 39.7 | 22.0 | 13.3 |
   < 6 | 11,202 |  |  | 24.1 | 35.2 | 26.8 | 13.9 |
   6 to 11 | 7,124 |  |  | 19.5 | 38.2 | 26.9 | 15.4 |
   12 to 23 | 6,486 |  |  | 11.1 | 28.4 | 35.3 | 25.2 |
   ≥ 24 | 3,642 |  |  | 3.3 | 17.2 | 44.2 | 35.3 |