Socio-economic status, smoking during pregnancy and birth outcomes: an analysis of cross-sectional community studies in Liverpool (1993-2001)

Objective: To assess the influence of socio-economic status on pregnancy outcomes in smoking mothers. Study design: Retrospective analysis. Methods: Parent-completed questionnaires addressing pregnancy smoking patterns and birth outcomes. Were distributed via children aged 5-11 years attending 10 primary schools in Merseyside. Data from three communitybased cross-sectional surveys undertaken in 1993, 1998 and 2001 were analysed. Townsend score was used as an indicator of household socioeconomic status. Results: 82.2 percent (n = 3730) of respondents were classified as low (disadvantaged) socio-economic status. One-third of mothers smoked during pregnancy and this proportion was significantly higher among disadvantaged than advantaged categories (37.7% versus 14.6%; p < 0.001). The logistic regression analysis showed that only maternal smoking during preg-nancy was a significant risk factor for adverse birth outcomes when socioeconomic variables were controlled. Conclusion: Birth outcomes were worse in babies of smoking mothers during pregnancy independent of household's socio-economic status.