Results of previous studies on smoking in pregnancy and infant death have been inconsistent (6–26), and it is possible that an apparent association between smoking and mortality can be explained by differences between smokers and non-
smokers in social class and in other lifestyle factors. Only if smoking is causally related to mortality is it possible to reduce the number of infant deaths by interventions directed at reducing the number of pregnant smokers.
The aim of this study was to evaluate the association between exposure to tobacco smoke in utero and the risk of stillbirth and increased mortality in the first year of life while taking into account a number of potential confounders and effect modifiers.