Table 1

 Background characteristics of 12 002 women of the Northern Finland 1966 Birth Cohort according to parity

Final parity
1 (n = 746)2–4 (n = 7913)5–9 (n = 2825)⩾10 (n = 518)p Value*
BMI, body mass index.
*Student t test for continuous variables, χ2 test for categorical variables.
†Age represented in years, as mean (SD).
Age at menarche†13.6 (1.6)13.9 (1.4)14.4 (1.4)14.2 (1.5)<0.001
Age at first birth†24.0 (5.3)22.8 (3.8)22.4 (3.4)22.2 (2.8)<0.001
Age in 1966†24.0 (5.3)26.1 (5.6)32.2 (6.5)35.2 (7.1)<0.001
Age at death†50.1 (12.0)53.9 (10.9)60.2 (11.2)65.6 (9.3)<0.001
Age in 2001†59.4 (5.0)61.4 (5.5)67.2 (6.3)69.6 (7.2)<0.001
Socioeconomic position in 1966 (%)<0.001
    White collar19.826.416.213.3
    Blue collar42.837.122.217.2
    Unskilled workers26.122.726.819.5
    Farmers8.212.233.949.0
    Missing3.11.60.81.0
Pre-pregnancy BMI in 1966 (%)<0.001
    <25.080.476.556.746.5
    25.0–29.99.414.123.528.4
    ⩾30.00.92.07.210.2
    Missing9.27.512.514.9
Smoking before pregnancy in 1966 (%)<0.001
    No63.874.581.487.8
    Yes33.823.115.910.8
    Missing2.42.42.71.4
Parity in 1966 (%)<0.001
    1100.036.77.16.6
    2–462.429.214.3
    5–9062.932.1
    ⩾100045.2
    Missing data in 19660.80.81.9