Table 2

Prevalence of PTB according to employment status and working condition: Amsterdam Born Children and their Development study, Amsterdam, the Netherlands, 2003–2004 (N=7561)

Total NPTBPTBPTB
Total (%)Spontaneous (%)Iatrogenic (%)
Weekly working hours
 Unemployed26965.74.31.4
 8–31 (ref)18894.94.01.0
 32–4026765.54.41.0
 >403005.84.31.3
Weekly standing/walking hours
 Unemployed26965.74.31.4
 <10 (ref)27644.73.90.8
 10–1910115.34.50.9
 20–305745.64.51.0
 >303568.45.92.5
Physical work load
 Unemployed26965.74.31.4
 Low (ref)26064.84.10.7
 Moderate16925.94.51.4
 High5025.84.01.8
Job strain
 Unemployed26965.74.31.4
 Low (ref)21704.74.00.7
 Moderate21525.74.41.3
 High3165.44.11.3
  • Sample sizes differ slightly because of missing values.

  • PTB, preterm birth.