Table 2

Maternal background characteristics by socioeconomic group and by time period, Finland, 1991–1999 (n=557293)*

Total1991–19931994–19961997–1999p†
*All differences between the socioeconomic groups are statistically significant, p<0.001.
†p Value for trend over time.
Births (n)557293196570187906172817
Maternal age, mean and SD, years
    Upper white collar workersI32.04.531.74.232.05.132.34.20.026
    Lower white collar workersII30.14.829.54.830.24.730.65.00.094
    Blue collar workersIII28.65.228.15.128.75.129.15.20.169
    OthersO27.75.827.85.827.55.727.85.80.987
Total29.65.029.35.029.65.129.95.10.080
Number of previous pregnancies, mean and SD
    Upper white collar workersI1.31.41.21.41.31.41.31.50.058
    Lower white collar workersII1.41.61.41.51.41.51.51.70.070
    Blue collar workersIII1.51.51.41.41.51.51.61.60.305
    OthersO1.82.21.92.21.82.21.72.20.126
Total1.51.71.51.61.51.71.51.70.005
Number of previous births, mean and SD
    Upper white collar workersI0.91.10.91.10.91.10.91.10.899
    Lower white collar workersII1.01.21.01.21.01.21.11.3<0.001
    Blue collar workersIII1.01.11.01.11.01.11.01.20.346
    OthersO1.31.91.41.91.31.91.21.80.012
Total1.11.31.01.31.11.31.11.40.306
Single mother, %
    Upper white collar workersI5.03.36.35.50.118
    Lower white collar workersII7.95.19.79.1<0.001
    Blue collar workersIII12.99.115.614.20.004
    OthersO10.37.312.211.80.002
Total8.96.010.810.10.529
Smoked during pregnancy, %
    Upper white collar workersI4.65.54.24.1<0.001
    Lower white collar workersII13.014.212.612.10.475
    Blue collar workersIII26.028.225.224.5<0.001
    OthersO18.018.118.017.9<0.001
Total15.216.314.714.40.314
Multiple birth, %
    Upper white collar workersI1.81.51.82.10.158
    Lower white collar workersII1.61.41.61.80.063
    Blue collar workersIII1.41.41.41.50.058
    OthersO1.31.21.21.40.080
Total1.51.41.51.70.076