Characteristics (mean±SD or %) of mothers who gave birth to singletons in Sweden during 1994–2014 and who worked full or part time, by exposure to whole-body vibrations and mechanical shocks (n=1 091 044 births)
| Maternal characteristics | Whole-body vibration exposure (m/s2) | Exposure to mechanical shocks | ||||
| 0 | 0.1–0.2 | 0.3–0.4 | ≥0.5 | No | Yes | |
| n=1 070 816 (98.2 %) | n=15 241 (1.4 %) | n=2975 (0.3 %) | n=2012 (0.2 %) | n=1 089 282 (99.8%) | n=1762 (0.2%) | |
| Age (years) 0% missing | 30.4±4.8 | 30.5±4.8 | 30.5±4.6 | 28.2±4.7 | 30.4±4.8 | 29.9±4.7 |
| BMI (%) 7% missing | ||||||
| <18.5 kg/m2 | 2.1 | 1.5 | 1.5 | 2.0 | 2.1 | 1.5 |
| 18.5–24.9 kg/m2 | 64.0 | 62.1 | 54.7 | 52.0 | 63.9 | 57.0 |
| 25–29.9 kg/m2 | 24.0 | 26.7 | 28.2 | 27.5 | 24.1 | 28.4 |
| ≥30 kg/m2 | 9.9 | 9.7 | 15.6 | 18.5 | 9.9 | 13.2 |
| Parity (birth order of child) 0% missing | 1.8±0.90 | 1.7±0.91 | 1.8±0.95 | 1.7±0.91 | 1.8±0.90 | 1.7±0.83 |
| Educational level (%) <1% missing | ||||||
| ≤Elementary | 6.7 | 7.6 | 7.8 | 14.0 | 6.7 | 10.9 |
| High school | 47.2 | 48.8 | 61.6 | 79.2 | 47.3 | 55.0 |
| Higher education <3 years | 13.7 | 29.3 | 19.8 | 4.6 | 13.9 | 18.6 |
| Higher education ≥3 years | 32.4 | 14.3 | 10.8 | 2.2 | 32.1 | 15.5 |
| Smoking (%) 1% missing | ||||||
| Non-smoking | 92.0 | 90.9 | 91.8 | 82.7 | 92.0 | 88.2 |
| 1–9 cigarettes/day | 5.9 | 5.9 | 5.3 | 10.6 | 5.9 | 7.4 |
| ≥10 cigarettes/day | 2.1 | 3.2 | 2.9 | 6.7 | 2.1 | 4.5 |
| Nationality (%) 0% missing | ||||||
| Swedish | 94.1 | 96.1 | 96.9 | 96.6 | 94.1 | 96.5 |
| European | 3.6 | 2.6 | 2.4 | 2.3 | 3.6 | 2.4 |
| Other | 1.4 | 0.6 | 0.0 | 0.3 | 1.4 | 0.1 |
| Unknown | 0.9 | 0.7 | 0.7 | 0.8 | 0.8 | 1.0 |
| Noise (%) <1% missing | ||||||
| <70 dB | 63.8 | 6.0 | 0.0 | 0.0 | 62.8 | 0.0 |
| 70–74 dB | 18.1 | 91.3 | 40.6 | 0.0 | 19.2 | 9.6 |
| 75–79 dB | 5.2 | 2.0 | 58.4 | 88.5 | 5.3 | 72.9 |
| 80–84 dB | 12.0 | 0.7 | 0.0 | 11.5 | 11.8 | 17.5 |
| ≥85 dB | 0.9 | 0.0 | 1.0 | 0.0 | 0.9 | 0.0 |
| Mechanical shocks (% Yes/No) 0% missing | 0/100 | 1.3/98.7 | 19.3/80.7 | 48.8/51.2 | 0/100 | 100/0 |
| Combustion particles* (% Yes/No) <1% missing | 3.5/96.5 | 47.4/52.6 | 65.1/34.9 | 99.2/0.8 | 4.4/95.6 | 79.3/20.7 |
| Job strain (%) 0% missing | ||||||
| Low strain (low demands+high control) | 13.6 | 0.1 | 18.4 | 0.0 | 13.3 | 29.7 |
| Active (high demands+high control) | 37.4 | 38.8 | 0.0 | 0.0 | 37.3 | 8.6 |
| High strain (high demands+low control) | 14.2 | 12.0 | 50.1 | 51.2 | 14.3 | 3.3 |
| Passive (low demands+low control) | 34.8 | 49.1 | 31.5 | 47.8 | 35.1 | 58.4 |
| Physically strenuous work† (index 1–6) 0% missing | 2.1±0.7 | 2.5±0.8 | 2.7±0.7 | 3.0±0.3 | 2.1±0.70 | 2.7±0.7 |
*Based on exposure to asphalt, diesel, polycyclic aromatic hydrocarbons, lead and/or other combustion particles.
†Average of indices (physically strenuous work) or combination of low/high demands/control (job strain), based on questions about control, demands, turning, lifting, bending, heavy breathing, working with hands above the head or with heavy objects, and repeated movements.
BMI, body mass index.