Table 1

Working conditions and preterm birth: distributions and adjusted odds ratios

Term birthsPreterm birthsS1adj OR* (95% CI)
⩾37 weeks22–36 weeks
S1 is the p value comparing both distributions, χ2 test. *Adjusted for age, educational level, marital status, obstetrical history, and country. One model was calculated for each of the variables describing working conditions.
Number of employed women after the third month of pregnancy (4049) (2329)
Occupational groups (ILO code)
Professionals or managers (1+2)23.320.31
Associate professionals (3)19.316.90.99(0.8 to 1.2)
Clerks (4)21.020.10.93(0.8 to 1.1)
Services and sales workers (5+0)19.121.51.05(0.9 to 1.3)
Craft and related trades workers (7)7.16.60.96(0.7 to 1.2)
Other manual workers (6+8+9)10.214.60.0011.37(1.1 to 1.7)
(3984)(2308)
Daily commuting time (home to work)
less 60 minutes62.362.91
60–120 minutes30.029.50.94(0.8 to 1.1)
more than 120 minutes7.77.60.8830.97(0.8 to 1.2)
(3907)(2230)
Weekly working hours
less than 3016.617.51.06(0.9 to 1.3)
30–3926.224.81
40–4247.445.11.09(0.9 to 1.3)
43 or more9.812.60.0041.33(1.1 to 1.6)
(3871)(2221)
Night work
yes6.96.40.4460.92(0.7 to 1.1)
(4009)(2300)
Shift work
yes18.318.20.9130.97(0.8 to 1.1)
(4009)(2300)
Standing position
less than 2 h55.452.81
2–6 h24.623.71.06(0.9 to 1.2)
more than 6 h20.023.50.0041.26(1.1 to 1.5)
(4036)(2317)
Strenuous posture
never43.541.21
less than 25% time23.323.50.99(0.9 to 1.1)
more than 25% time33.235.30.1321.07(0.9 to 1.2)
(4034)(2316)
no64.763.91
more than 5 kg24.425.11.00(0.9 to 1.1)
more than 20 kg10.911.00.7921.02(0.8 to 1.2)
(4025)(2314)
Work with industrial machines
Yes12.013.10.1711.05(0.9 to 1.2)
(4013)(2306)
Work on assembly line
Yes3.73.90.7510.98(0.7 to 1.3)
(4023)(2305)
Work with a video display monitor
No66.871.21
less than 50% time12.811.50.93(0.8 to 1.1)
more than 50% time20.417.30.0010.85(0.7 to 1.0)
(4032)(2310)
Yes3.01.90.0120.76(0.5 to 1.1)
(4029)(2307)
Contact with biological substances
Yes11.210.40.3670.93(0.8 to 1.1)
(4028)(2309)
Contact with suspected mutagenic chemicals*
Yes18.218.00.8391.01(0.9 to 1.2)
(4030)(2310)
Contact with paints or heavy metals
Yes6.16.30.7581.08(0.9 to 1.3)
(4028)(2308)
Noise
Yes26.527.70.2960.99(0.9 to 1.1)
(4036)(2316)
Work at high speed
yes51.553.70.0841.02(0.9 to 1.1)
(4026)(2311)
Repetitive work
yes29.730.50.5101.04(0.9 to 1.2)
(4029)(2315)
Pause at convenience
no33.435.00.1981.00(0.9 to 1.1)
(4031)(2315)
Autonomy at work
no34.336.90.0341.11(1.0 to 1.2)
(4031)(2314)
Job satisfaction
very satisfied37.637.81
satisfied50.147.10.99(0.9 to 1.1)
not satisfied12.315.10.0041.27(1.1 to 1.5)
(4034)(2317)