You snus you lose? The effect of Swedish snus on offspring birthweight: a quasi-experimental sibling analysis

The association between maternal smoking during pregnancy and offspring’s birthweight reduction is very well established. However, less is known about the effect of smokeless tobacco on birthweight and about the specific mechanism through which smoking reduces birthweight. This paper aimed at filling these knowledge gaps by studying the effect of maternal Swedish snuff use during pregnancy (SUDP) on offspring’s birthweight. Swedish snuff is grounded tobacco without any toxic substance added, which provides us with the opportunity to isolate the effect of nicotine on birthweight. With data from the Swedish Medical Birth Register (2002-2009), we applied a sibling analysis using multilevel linear regression model (50,497 siblings nested within 23,443 mothers). This design has potential to study causal associations since, it accounts for unknown genetic and environmental characteristics of the mother associated to both tobacco habits and offspring birthweight. Our results show that SUDP does not have an effect on birthweight reduction.