Associations of birth outcomes with non-occupational risk factors
| Risk factor | Preterm delivery | Small for gestational age | Small head circumference | Small abdominal circumference | ||||
| OR* (95% CI) | p Value | OR* (95% CI) | p Value | OR* (95% CI) | p Value | OR* (95% CI) | p Value | |
| Maternal age† | 1.01 (0.93 to 1.10) | 0.8 | 1.04 (0.98 to 1.11) | 0.2 | 0.99 (0.95 to 1.04) | 0.8 | 1.05 (1.00 to 1.10) | 0.07 |
| Female baby | 1.04 (0.58 to 1.89) | 0.9 | –‡ | –‡ | 1.22 (0.85 to 1.76) | 0.3 | ||
| Consumed ⩾14 units of alcohol per week before pregnancy | 0.73 (0.33 to 1.63) | 0.4 | 1.23 (0.74 to 2.04) | 0.4 | 0.81 (0.50 to 1.31) | 0.4 | 1.00 (0.64 to 1.57) | 1.0 |
| Smoked before pregnancy | 0.63 (0.29 to 1.36) | 0.2 | 1.59 (0.98 to 2.58) | 0.06 | 1.08 (0.71 to 1.65) | 0.7 | 1.43 (0.94 to 2.17) | 0.09 |
| Educational level§ | 0.89 (0.70 to 1.12) | 0.3 | 0.90 (0.75 to 1.07) | 0.2 | 0.87 (0.75 to 1.01) | 0.07 | 0.93 (0.81 to 1.08) | 0.3 |
| Primiparous | 2.03 (1.04 to 3.95) | 0.04 | 2.62 (1.55 to 4.42) | <0.001 | 1.51 (1.01 to 2.25) | 0.04 | 2.22 (1.46 to 3.37) | <0.001 |
| Maternal BMI before pregnancy¶ | 0.96 (0.89 to 1.03) | 0.2 | 0.94 (0.89 to 1.00) | 0.04 | 0.98 (0.94 to 1.02) | 0.3 | 0.99 (0.95 to 1.03) | 0.7 |
*For each outcome, all risk factors were examined in a single logistic regression model, and odds ratios are therefore mutually adjusted.
†Maternal age was analysed as a continuous variable. Risk estimates are for a 1-year increase in age.
‡Not applicable because outcome was adjusted for the sex of the baby.
§Educational level was analysed as an ordinal variable with six levels defined as in table 1. Risk estimates are for an increase of one level.
¶Maternal BMI was analysed as a continuous variable. Risk estimates are for an increase of 1 kg/m2.
BMI, bodymass index.