Table 3

Relative pregnancy risks estimated from hazard regression models. Respondents to the 1987–1997 surveys

Baseline models: Age+VariableMultivariate model*
Variable CategoryRelative risk95% confidence intervalsRelative risk95% confidence intervals
*Multivariate model = Age + Year + Occupation + Education + Both parents + Mother tongue + Province.
†The relative risks presented for age in the baseline model (first column) are estimated from a model that contains only age. Those relative risks that differ significantly from the reference category at 95% confidence level are in bold type.
Age†
    14 0.05 0.03 to 0.08 0.05 0.03 to 0.09
    15 0.14 0.11 to 0.18 0.15 0.12 to 0.19
    16 0.28 0.24 to 0.33 0.28 0.24 to 0.33
    17 0.43 0.38 to 0.48 0.44 0.39 to 0.49
    18 0.76 0.70 to 0.83 0.75 0.68 to 0.82
    191 (ref)1 (ref)
Year
    19871 (ref)1 (ref)
    19880.900.72 to 1.110.930.74 to 1.16
    19891.040.85 to 1.271.080.88 to 1.34
    19900.920.74 to 1.130.980.78 to 1.22
    19910.970.80 to 1.170.980.80 to 1.19
    1992 0.73 0.59 to 0.89 0.73 0.59 to 0.90
    1993 0.67 0.55 to 0.81 0.69 0.56 to 0.84
    1994 0.78 0.64 to 0.93 0.82 0.67 to 1.00
    1995 0.81 0.67 to 0.960.850.71 to 1.03
    1996 0.73 0.60 to 0.88 0.77 0.63 to 0.94
    1997/1998 0.74 0.62 to 0.89 0.79 0.66 to 0.96
Father’s or guardian’s occupation
    Upper white collar1 (ref)1 (ref)
    Lower white collar 1.90 1.66 to 2.18 1.27 1.08 to 1.50
    Farmer 1.53 1.27 to 1.841.120.90 to 1.40
    Blue collar 2.46 2.16 to 2.79 1.61 1.35 to 1.90
Father’s or guardian’s level of education
    12 or more years1 (ref)1 (ref)
    9–11 years 1.39 1.16 to 1.651.150.94 to 1.40
    Not more than 8 years 2.21 1.92 to 2.54 1.63 1.36 to 1.95
Living with both parents
    Yes1 (ref)1 (ref)
    No 2.29 2.12 to 2.47 2.24 2.06 to 2.44
Mother tongue
    Finnish1 (ref)1 (ref)
    Swedish 0.61 0.46 to 0.80 0.68 0.50 to 0.93
Urbanisation
    Sparsely populated rural areas1 (ref)
    Towns and other settlements 1.19 1.06 to 1.33ns
    Larger towns 1.22 1.06 to 1.41
    Capital city area1.150.98 to 1.35
Region (province)
    Central and western:
        Central Finland1 (ref)1 (ref)
        Vaasa0.960.79 to 1.171.050.86 to 1.28
    South:
        Uusimaa0.960.81 to 1.141.050.88 to 1.25
        Kymi 0.79 0.64 to 0.97 0.75 0.61 to 0.93
    Southwest:
        Turku1.020.85 to 1.231.020.85 to 1.22
        Häme1.000.83 to 1.211.000.83 to 1.20
    East:
        Mikkeli0.890.72 to 1.100.870.71 to 1.08
        North Karelia1.110.90 to 1.371.090.89 to 1.35
        Kuopio1.110.92 to 1.351.090.90 to 1.32
    North:
        Oulu1.170.97 to 1.411.201.00 to 1.44
        Lapland 1.32 1.09 to 1.60 1.29 1.07 to 1.56