Table 1.
Characteristics of 365 premenopausal women recruited during annual screening mammography at the Joanne Knight Breast Health Center, Washington University School of Medicine, St. Louis, MO.
| Body size at age 10 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1–2 | 3–4 | 5 | 6+ | p-trenda | |||||
| N | Mean± SD /Percentage | N | Mean± SD /Percentage | N | Mean± SD /Percentage | N | Mean± SD /Percentage | ||
| Attained age (years) | 158 | 47.54 ± 4.83 | 129 | 46.72 ± 4.43 | 51 | 46.83 ± 4.71 | 27 | 45.50 ± 6.15 | 0.038 |
| Menarche (years) | 158 | 13.02 ± 1.56 | 129 | 12.71 ± 2.86 | 51 | 12.43 ± 1.63 | 27 | 12.78 ± 1.58 | 0.144 |
| Age at first birth (years) | 138 | 26.09 ± 6.12 | 98 | 26.35 ± 5.77 | 38 | 26.03 ± 6.72 | 19 | 24.84 ± 6.24 | 0.598 |
| Birth index b (years) | 158 | 36.61 ± 25.12 | 129 | 28.66 ± 23.79 | 51 | 26.78 ± 24.90 | 27 | 31.54 ± 32.66 | 0.023 |
| Parity | 0.008 | ||||||||
| Nulliparous | 20 | 12.66% | 31 | 24.03% | 13 | 25.49% | 8 | 29.63% | |
| One | 24 | 15.19% | 25 | 19.38% | 13 | 25.49% | 4 | 14.81% | |
| Two | 68 | 43.04% | 43 | 33.33% | 15 | 29.41% | 6 | 22.22% | |
| Three or more | 46 | 29.11% | 30 | 23.26% | 10 | 19.61% | 9 | 33.33% | |
| Ever breastfed | 100 | 63.29% | 73 | 56.59% | 28 | 54.90% | 13 | 48.15% | 0.085 |
| Ever used oral contraceptives | 148 | 91.77% | 113 | 87.60% | 45 | 88.24% | 22 | 77.78% | 0.049 |
| Family history of breast cancer | 33 | 20.89% | 30 | 23.26% | 13 | 25.49% | 10 | 37.04% | 0.095 |
| Race | 0.265 | ||||||||
| Non-Hispanic White | 109 | 68.99% | 87 | 67.44% | 29 | 56.86% | 18 | 66.67% | |
| Black or African American | 44 | 27.85% | 33 | 25.58% | 17 | 33.33% | 9 | 33.33% | |
| Others | 5 | 3.16% | 9 | 6.98% | 5 | 9.8% | 0 | 0 | |
| Education level | 0.359 | ||||||||
| High school or less than high school | 15 | 9.49% | 10 | 7.75% | 6 | 11.76% | 3 | 11.11% | |
| Post high school training or some college | 31 | 19.62% | 23 | 17.83% | 10 | 19.61% | 10 | 37.04% | |
| College graduate | 67 | 42.41% | 46 | 35.66% | 16 | 31.37% | 10 | 37.04% | |
| Postgraduate | 44 | 27.85% | 50 | 38.76% | 19 | 37.25% | 4 | 14.81% | |
| Adiposity measures | |||||||||
| Attained height (cm) | 158 | 164.62 ± 6.79 | 129 | 164.03 ± 7.09 | 51 | 164.25± 9.04 | 27 | 166.47 ± 5.52 | 0.556 |
| Attained weight (kg) | 158 | 77.72 ± 19.51 | 129 | 81.51 ± 21.42 | 51 | 92.68 ± 23.82 | 27 | 98.33± 15.21 | <0.001 |
| Attained BMI (kg/m2) | 158 | 28.69 ± 7.10 | 129 | 30.29 ± 7.84 | 51 | 34.49 ± 9.06 | 27 | 35.45 ± 5.00 | <0.001 |
a
Linear trends for continuous variables and heterogeneity for categorical variables were tested across body size groups using linear regression model and Chi- square test, respectively.
b
Birth index (years)= attained age minus age at each given birth (the birth index is 0 for nulliparous women).