Table 3 Risk of preterm birth in the educational groups after adjustment for all relevant covariates
VariablesCategoriesRegression coefficients (95% CI)
Model 1 (BM)Model 2Model 3
Maternal educationHighReferenceReferenceReference
Mid–high0.81 (0.53 to 1.25)0.83 (0.54 to 1.27)0.81 (0.53 to 1.25)
Mid–low0.65 (0.41 to 1.04)0.67 (0.42 to 1.07)0.65 (0.41 to 1.04)
Low1.10 (0.66 to 1.84)1.28 (0.78 to 2.12)1.10 (0.66 to 1.84)
ParityPrimipara1.41 (0.99 to 2.00)1.61 (1.15 to 2.27)1.41 (0.99 to 2.00)
GenderGirl0.83 (0.61 to 1.13)0.89 (0.66 to 1.21)0.83 (0.61 to 1.13)
Maternal age0.93 (0.76 to 1.13)0.88 (0.72 to 1.08)
Maternal height0.71 (0.59 to 0.86)0.74 (0.61 to 0.90)
PreeclampsiaYes4.73 (2.49 to 9.00)
IUGRYes8.31 (4.32 to 15.99)
Financial concernsNo concernsReferenceReference
Some concerns1.38 (0.86 to 2.23)1.36 (0.79 to 2.33)
Great concerns1.43 (0.44 to 4.67)1.13 (0.31 to 4.16)
Long-lasting difficulties0.98 (0.80 to 1.20)0.95 (0.75 to 1.20)
Psychopathology1.04 (0.91 to 1.19)1.10 (0.96 to 1.26)
Smoking habitsNoReferenceReference
Until pregnancy known1.03 (0.60 to 1.76)1.05 (0.60 to 1.81)
Continued during pregnancy0.97 (0.62 to 1.50)1.01 (0.65 to 1.58)
Alcohol consumptionNoReferenceReference
<1 drink per week0.85 (0.60 to 1.22)0.86 (0.60 to 1.24)
⩾1 drink per week0.78 (0.47 to 1.30)0.80 (0.48 to 1.34)
BMI<181.43 (0.32 to 6.31)1.60 (0.36 to 7.05)
18–25ReferenceReference
>251.06 (0.77 to 1.47)1.05 (0.75 to 1.46)
  • BM, basic model; BMI, body mass index; IUGR, intrauterine growth restriction.