Results of the combined exposure of weekly working hours and physical work load on iatrogenic PTB in employed women only (N=4865)
| N | Iatrogenic PTB | Adjusted* | ||
| OR (95% CI) | ||||
| Crude | ||||
| Physical work load | ||||
| Weekly working hours | Low (ref) | 824 | 1.0 | 1.0 |
| 8–31 | Moderate | 784 | 1.27 (0.25–3.59) | 1.16 (0.22–4.87) |
| High | 262 | 2.58 (0.90–7.35) | 2.24 (0.87–6.50) | |
| Weekly working hours | Low | 1790 | 1.29 (0.46–3.60) | 0.97 (0.34–2.76) |
| ≥32 | Moderate | 919 | 2.01 (0.69–5.80) | 1.25 (0.42–3.72) |
| High | 242 | 4.92 (1.55–13.96) | 3.42 (1.04–8.21) | |
Goodness of fit tests showed no evidence of lack of fit (p>0.40 for the adjusted logistic model).
Bold values indicate statistically significance at the level of p<0.05.
*Model adjusted for: parity, smoking, previous PTB, ethnicity, maternal educational level, maternal age and maternal pre-pregnancy BMI.
BMI, body mass index; PTB, preterm birth.