Table 3

Univariate and multivariate effects of working conditions on PTB and its subtypes: ABCD study, Amsterdam, the Netherlands, 2003–2004 (N=7561)

Total PTBSpontaneous PTBIatrogenic PTB
CrudeAdjusted*CrudeAdjusted*CrudeAdjusted†*
Or (95% CI)Or (95% CI)Or (95% CI)Or (95% CI)Or (95% CI)Or (95% CI
Employed
 Yes1.01.01.01.01.01.0
 No1.07 (0.87–1.32)1.06 (0.83–1.36)1.01 (0.80–1.27)0.98 (0.74–1.30)1.32 (0.86–2.03)1.39 (0.89–2.31)
Weekly working hours†
 8–31 (ref)1.01.01.01.01.01.0
 32–401.09 (0.83–1.42)1.79 (0.42–1.47)1.12 (0.83–1.51)0.97 (0.71–1.33)1.01 (0.56–1.81)0.79 (0.42–1.47)
 >401.15 (0.67–3.95)1.3 (0.8–2.3)1.11 (0.61–2.02)0.95 (0.51–1.78)1.33 (0.45–3.93)1.15 (0.37–3.55)
Weekly standing/walking hours†
 <10 (ref)1.01.01.01.01.01.0
 10–191.14 (0.82–1.58)1.10 (0.79–1.53)1.16 (0.81–1.65)1.11 (0.77–1.59)1.08 (0.50–2.33)1.07 (0.49–2.34)
 20–301.21 (0.81–1.79)1.08 (0.72–1.62)1.19 (0.77–1.84)1.08 (0.69–1.69)1.28 (0.52–3.15)1.12 (0.45–2.81)
 >301.80 (1.19–2.74)1.44 (1.01–2.24)1.58 (1.00–2.56)1.30 (0.78–2.16)2.81 (1.25–6.33)2.09 (1.00–4.97)
Physical work load†
 Low (ref)1.01.01.01.01.01.0
 Moderate1.23 (0.93–1.61)1.11 (0.84–1.48)1.11 (0.82–1.50)1.01 (0.74–1.39)1.89 (1.03–3.48)1.66 (0.88–3.13)
 High1.18 (0.78–1.81)0.95 (0.60–1.50)1.00 (0.61–1.63)0.81 (0.48–1.37)2.23 (1.01–5.11)1.68 (0.67–4.22)
Job strain†
 Low (ref)1.01.01.01.01.01.0
 Moderate1.20 (0.92–1.57)1.18 (0.90–1.55)1.11 (0.83–1.49)1.09 (0.81–1.47)1.70 (0.93–3.13)1.65 (0.89–3.05)
 High1.14 (0.68–1.93)1.02 (0.60–1.76)1.04 (0.57–1.88)0.96 (0.52–1.77)1.71 (0.57–5.11)1.37 (0.44–4.27)
  • Goodness of fit tests showed no evidence of lack of fit (p>0.0.07 for the three adjusted logistic models).

  • 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.

  • †Only employed women included (paid work for at least 8 hours/week, N=4865).

  • .ABCD, Amsterdam Born Children and their Development; BMI, body mass index; PTB, preterm birth.