Table 1.
Characteristics of Study Sample, NIEHS Uterine Fibroid Study, Enrollment 1996–1999.
| Characteristic | Total | Blacks | Whites |
|---|---|---|---|
| n = 1036 | n = 620 | n = 416 | |
| n (%) | n (%) | n (%) | |
| Age | |||
| 35–39 | 362 (35) | 222 (36) | 140 (34) |
| 40–44 | 365 (35) | 225 (36) | 140 (34) |
| 45–49 | 309 (30) | 173 (28) | 136 (33) |
| Education | |||
| High school or less | 139 (14) | 127 (21) | 12 (3) |
| Some college or technical school | 316 (31) | 283 (47) | 33 (8) |
| College degree | 261 (26) | 126 (21) | 135 (34) |
| Post graduate degree | 289 (29) | 68 (11) | 221 (55) |
| Missing | 31 | 16 | 15 |
| Parity | |||
| 0 | 372 (36) | 132 (21) | 240 (58) |
| ≥1 | 664 (64) | 488 (79) | 176 (42) |
| Age of menarche | |||
| ≤10 | 86 (8) | 68 (11) | 18 (4) |
| 11 | 162 (16) | 101 (16) | 61 (15) |
| 12 | 285 (28) | 171 (28) | 114 (28) |
| 13 | 287 (28) | 147 (24) | 140 (34) |
| 14 | 106 (10) | 60 (10) | 46 (11) |
| ≥15 | 105 (10) | 70 (11) | 35 (8) |
| Missing | 5 | 3 | 2 |
| Body mass index (kg/m2) | |||
| <25 | 400 (39) | 159 (26 | 241 (58) |
| 25–29.9 | 287 (28) | 187 (30) | 100 (24) |
| 30–34.9 | 161 (16) | 123 (20) | 38 (9) |
| ≥35 | 187 (18) | 150 (24) | 37 (9) |
| Missing | 1 | 1 | 0 |
| Physical Activity | |||
| Low | 332 (32) | 221 (36) | 111 (27) |
| Moderate | 337 (33) | 196 (32) | 141 (34) |
| High | 191 (19) | 104 (17) | 87 (21) |
| Very high | 171 (17) | 95 (15) | 76 (18) |
| Missing | 5 | 4 | 1 |
| Plasma 25(OH) D | |||
| Insufficient (≤20 ng/ml) | 718 (74) | 521 (90) | 197 (50) |
| Sufficient (>20 ng/ml) | 258 (26) | 57 (10) | 201 (50) |
| Missing | 60 | 42 | 18 |
| Sun Exposure | |||
| Low (<1 hour/day outside) | 201 (19) | 105 (17) | 96 (23) |
| Medium (1 hour/day outside) | 333 (32) | 155 (25) | 178 (43) |
| High (>1 hour/day outside) | 499 (48) | 358 (58) | 141 (34) |
| Missing | 3 | 2 | 1 |
| Fibroid status | |||
| No fibroids | 362 (35) | 161 (26) | 201 (48) |
| Small (<4 cm diameter) | 471 (45) | 307 (50) | 164 (39) |
| Large (≥4 cm diameter) | 203 (20) | 152 (25) | 51 (12) |