Table 1 Characteristics of the Study Population by Daily Magnetic Field Exposure Level (Lowest or Higher Quartiles of MF 99th Percentile).
Characteristic | Total N (N = 913)a | 99th Percentile MF Level | |||
|---|---|---|---|---|---|
Lowest quartile (N = 219) | Higher quartiles (N = 694) | ||||
N | % | N | % | ||
Maternal age | |||||
<30 | 296 | 61 | 27.9% | 235 | 33.9% |
30–34 | 288 | 71 | 32.4% | 217 | 31.3% |
≥35 | 329 | 87 | 39.7% | 242 | 34.9% |
Race | |||||
White | 326 | 91 | 41.7% | 235 | 34.0% |
Black | 90 | 16 | 7.3% | 74 | 10.7% |
Hispanic | 226 | 51 | 23.4% | 175 | 25.3% |
Asian /Pacific Islander | 202 | 44 | 20.2% | 158 | 22.8% |
Other | 66 | 16 | 7.3% | 50 | 7.2% |
Education | |||||
<High school | 42 | 5 | 2.3% | 37 | 5.4% |
High school or GED | 142 | 32 | 14.7% | 110 | 15.9% |
Trade/Technical school | 46 | 5 | 2.3% | 41 | 5.9% |
College degree | 495 | 128 | 58.7% | 367 | 53.1% |
Graduate school | 184 | 48 | 22.0% | 136 | 19.7% |
Marital Status | |||||
Single | 72 | 12 | 5.5% | 60 | 8.7% |
Partnered | 147 | 31 | 14.2% | 116 | 16.8% |
Married | 690 | 175 | 80.3% | 515 | 74.5% |
Worked in last year | |||||
No | 183 | 47 | 21.6% | 136 | 19.7% |
Yes | 727 | 171 | 78.4% | 556 | 80.3% |
Smoked since LMP | |||||
No | 807 | 196 | 91.2% | 611 | 89.3% |
Yes | 92 | 19 | 8.8% | 73 | 10.7% |
Coffee intake since LMP | |||||
0 cup/day | 637 | 142 | 64.8% | 495 | 71.3% |
0–1 cup/day | 201 | 52 | 23.7% | 149 | 21.5% |
>1 cups/day | 75 | 25 | 11.4% | 50 | 7.2% |
Alcohol use since LMP | |||||
No | 514 | 127 | 58.3% | 387 | 55.8% |
Yes | 397 | 91 | 41.7% | 306 | 44.2% |
Number of previous pregnancies | |||||
0 | 94 | 21 | 9.6% | 73 | 10.5% |
1 | 103 | 18 | 8.2% | 85 | 12.2% |
2 | 140 | 36 | 16.4% | 104 | 15.0% |
≥3 | 576 | 144 | 65.8% | 432 | 62.2% |
Number of previous miscarriages | |||||
0 | 276 | 60 | 27.4% | 216 | 31.1% |
1 | 79 | 21 | 9.6% | 58 | 8.4% |
2 | 403 | 101 | 46.1% | 302 | 43.5% |
≥3 | 155 | 37 | 16.9% | 118 | 17.0% |
History of subfertility | |||||
No | 633 | 147 | 67.1% | 486 | 70.0% |
Yes | 280 | 72 | 32.9% | 208 | 30.0% |
Vaginal bleeding since LMP | |||||
No | 670 | 165 | 75.7% | 505 | 72.9% |
Yes | 241 | 53 | 24.3% | 188 | 27.1% |
Urinary tract infection since LMP | |||||
No | 860 | 211 | 96.8% | 649 | 93.9% |
Yes | 49 | 7 | 3.2% | 42 | 6.1% |
Fever since LMP | |||||
No | 851 | 198 | 92.1% | 653 | 94.8% |
Yes | 53 | 17 | 7.9% | 36 | 5.2% |
Carry loads (>10 pounds) since LMP | |||||
No | 416 | 92 | 42.2% | 324 | 46.8% |
Yes | 494 | 126 | 57.8% | 368 | 53.2% |
Used Jacuzzi/hot tub/steam room/sauna since LMP | |||||
No | 807 | 200 | 91.7% | 607 | 87.7% |
Yes | 103 | 18 | 8.3% | 85 | 12.3% |
Exposure to solvents or degreasers since LMP | |||||
No | 609 | 148 | 68.5% | 461 | 67.7% |
Yes | 288 | 68 | 31.5% | 220 | 32.3% |
Vitamin use since LMP | |||||
No | 91 | 16 | 7.3% | 75 | 10.8% |
Yes | 820 | 202 | 92.7% | 618 | 89.2% |
Gestational age at study entry | |||||
0–48 days | 763 | 173 | 79.0% | 590 | 85.0% |
49–69 days | 135 | 41 | 18.7% | 94 | 13.5% |
≥70 days | 15 | 5 | 2.3% | 10 | 1.4% |
