Table 4

Multivariable logistic regression analysis of the effects of individual characteristics and maternal occupational exposure during pregnancy on time to pregnancy (>6 months), preterm birth (<37 weeks) and decreased birth weight (<3000 g) among women in a birth cohort study

VariablesProlonged time to pregnancy (n=3719), OR (95% CI)Preterm birth (n=6302), OR (95% CI)Decreased birth weight (n=6201), OR (95% CI)
Individual characteristics
 Age at enrolment in study
  <25 years1.001.001.00
  25–30 years1.33 (0.99 to 1.78)**1.27 (0.88 to 1.84)1.04 (0.85 to 1.29)
  30–35 years1.97 (1.47 to 2.65)*1.39 (0.95 to 2.04)1.17 (0.94 to 1.46)
  ≥35 years3.90 (2.79 to 5.44)*1.51 (0.96 to 2.38)1.37 (1.06 to 1.78)*
 Educational level
  Low1.001.001.00
  Mid-low0.75 (0.60 to 0.94)*0.68 (0.50 to 0.93)*0.78 (0.65 to 0.93)*
  Mid-high0.47 (0.36 to 0.61)*0.60 (0.41 to 0.88)*0.62 (0.50 to 0.78)*
  High0.47 (0.36 to 0.60)*0.68 (0.47 to 0.99)*0.60 (0.48 to 0.75)*
 Country of origin
  Netherlands1.001.001.00
  Surinam and Dutch Antilles1.19 (0.87 to 1.61)1.38 (0.96 to 1.98)**2.60 (2.12 to 3.19)*
  Morocco and Turkey0.96 (0.73 to 1.27)0.93 (0.62 to 1.40)0.93 (0.73 to 1.19)
  Other1.00 (0.82 to 1.23)1.12 (0.84 to 1.51)1.26 (1.06 to 1.49)*
 Parity
  First child1.001.001.00
  Second child and higher0.50 (0.42 to 0.60)*0.56 (0.43 to 0.72)*0.48 (0.41 to 0.55)*
 Smoker during mid-pregnancy1.49 (1.17 to 1.89)*1.02 (0.73 to 1.43)1.64 (1.37 to 1.98)*
 Alcohol use during mid-pregnancy0.77 (0.64 to 0.92)*0.93 (0.71 to 1.21)0.90 (0.77 to 1.05)
 Paid employment0.94 (0.76 to 1.17)0.82 (0.61 to 1.10)**0.99 (0.83 to 1.18)
 Occupational exposure
 Manual materials handling ≥5 kg (self-report)0.82 (0.61 to 1.09)0.55 (0.32 to 0.95)*0.75 (0.58 to 0.98)*
 Pesticides (strict JEM definition)1.75 (0.59 to 5.18)2.10 (0.61 to 7.24)2.42 (1.10 to 5.34)*
 Phthalates (strict JEM definition)2.16 (1.02 to 4.57)*1.28 (0.39 to 4.20)2.42 (1.10 to 5.34)
 Solvents (strict JEM definition)1.09 (0.43 to 2.78)1.28 (0.51 to 3.23)0.93 (0.51 to 1.69)
  • * p<0.05;

  • ** p<0.10.

  • Included in final multivariable model for comparison.

  • JEM, job–exposure matrix.