Table 2.
Classification of Cell-Phone Exposure in 4 Cohorts Included in an Analysis of Maternal Cell-Phone Use During Pregnancy and Birth Outcomes, 1996–2011
| Exposure Classificationa | Study Cohort | Total (n = 55,507) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| DNBC (n = 49,668) | ABCD (n = 2,597) | INMA (n = 1,934) | MOCEH (n = 1,308) | |||||||
| No. of Pairsb | % | No. of Pairs | % | No. of Pairs | % | No. of Pairs | % | No. of Pairs | % | |
| None | 30,185 | 60.8 | 180 | 6.9 | 53 | 2.7 | 15 | 1.2 | 30,433 | 54.8 |
| Low | 10,860 | 21.9 | 1,125 | 43.3 | 703 | 36.4 | 242 | 18.5 | 12,930 | 23.3 |
| Intermediate | 6,172 | 12.4 | 703 | 27.1 | 753 | 38.9 | 642 | 49.1 | 8,270 | 14.9 |
| High | 2,451 | 4.9 | 589 | 22.7 | 425 | 22.0 | 409 | 31.3 | 3,874 | 7.0 |
Abbreviations: ABCD, Amsterdam Born Children and Their Development Study; DNBC, Danish National Birth Cohort; INMA, Spanish Environment and Childhood Project; MOCEH, Korean Mothers and Children’s Environment Health Study.
a In the DNBC, ABCD, and INMA cohorts, no exposure corresponded to no cell-phone use, low exposure to ≤1 calls/day, intermediate exposure to 2–3 calls/day, and high exposure to ≥4 calls/day. In the MOCEH cohort, no exposure corresponded to no cell-phone use, low exposure to ≤2 calls/day, intermediate exposure to 3–5 calls/day, and high exposure to ≥6 calls/day.
b Number of mother-child pairs.