Crude association of birth weight with environmental and occupational exposures and maternal and infant characteristics
| Variable | n | Estimated2-150change in birth weight | p Value | (95% CI) |
| Maternal characteristics: | ||||
| Age (y): | ||||
| 20–25 | 164 | Referent | ||
| 26–29 | 526 | 21 | 0.559 | (−50 to 91) |
| 30–40 | 102 | 167 | 0.001 | (68 to 266) |
| Height tertile before pregnancy (cm): | ||||
| 1st (147–159) | 244 | Referent | ||
| 2nd (160–163) | 314 | 24 | 0.478 | (−43 to 92) |
| 3rd (164–180) | 234 | 112 | 0.003 | (40 to 184) |
| BMI tertile before pregnancy (kg/m2): | ||||
| 1 (14.17–20.31) | 264 | Referent | ||
| 2 (20.32–23.42) | 260 | 64 | 0.068 | (−5 to 133) |
| 3 (23.43–37.46) | 268 | 100 | 0.004 | (31 to 168) |
| College education or above | 250 | 89 | 0.004 | (28 to 149) |
| Passive smoking | 457 | −53 | 0.066 | (−109 to 4) |
| Infant characteristics: | ||||
| Parity (one or more) | 32 | 83 | 0.257 | (−60 to 25) |
| Female baby | 386 | −97 | 0.001 | (−153 to −40) |
| Occupational exposures: | ||||
| Exposure to benzene | 354 | −58 | 0.044 | (−115 to −2) |
| Perceived work stress | 142 | −84 | 0.026 | (−158 to −10) |
| Noise at work | 207 | −36 | 0.275 | (−100 to 29) |
| Physical exertion | 194 | −32 | 0.337 | (−98 to 33) |
| Other hazards | 108 | −30 | 0.471 | (−112 to 52) |
| Work mainly in a sitting posture | 495 | 18 | 0.552 | (−41 to 76) |
↵2-150 All the estimates were derived from a linear regression model with adjustment for a linear and a square terms of gestational age.