Table 4

Associations of low birth weight (small for gestational age) with occupational activities

Occupational activity11 weeks of gestation19 weeks of gestation34 weeks of gestation
No exposed (%)No exposed casesOR* (95% CI)No exposed (%)No exposed casesOR* (95% CI)No exposed (%)No exposed casesOR* (95% CI)
Worked ⩾40 h/week242 (19)221.11 (0.66 to 1.88)233 (18)221.19 (0.70 to 2.01)127 (16)141.29 (0.67 to 2.47)
Standing or walking >4 h/day in total476 (36)310.93 (0.59 to 1.46)425 (33)301.06 (0.67 to 1.69)196 (24)130.86 (0.45 to 1.64)
Kneeling/squatting >1 h/day in total218 (17)161.21 (0.68 to 2.15)208 (16)141.10 (0.60 to 2.00)81 (10)61.06 (0.43 to 2.60)
Trunk bent forward for >1 h/day in total581 (44)370.88 (0.56 to 1.37)561 (44)350.85 (0.54 to 1.33)309 (39)251.16 (0.67 to 2.01)
Lifting weights of ⩾25 kg by hand121 (9)91.09 (0.53 to 2.27)83 (7)61.06 (0.44 to 2.55)24 (3)2
Night shifts130 (10)80.92 (0.43 to 1.97)114 (9)70.92 (0.41 to 2.06)32 (4)2
  • *Each risk factor was examined in a separate logistic regression model with adjustment for maternal age, primiparity and maternal BMI and smoking before pregnancy, all classified as in table 2. Risk estimates are for those exposed to the risk factor relative to those who were in work at the relevant stage of pregnancy but unexposed.