Statistics show a direct relation between smoking during pregnancy and spontaneous abortions, stillbirths, death among newborns, and sudden infant death syndrome (SIDS).  

The risk of SIDS triples for babies of mothers who smoke during pregnancy; two-thirds of SIDS deaths among babies of women who smoked during pregnancy can be attributed to smoking.(American Canter Society)  

In fact, the risk of SIDS increases with the number of cigarettes the mother smokes (Archives of Disease in Childhood)  

SIDS is the leading cause of death in infants between the ages of 1 month and 1 year.