Fig. 1

Flowchart showing the number of included and excluded subjects. The discrepancy in the number of the smokers in different boxes is explained by the definition of the final Smokers group (≥ 5 cigarettes/day). Control mothers having increased risk ratio were excluded. Every 8th mother was selected randomly out of all the criteria fulfilling non-smoking mothers to obtain an appropriate number of controls. Thirty-three (42.3%) out of the 71 Abusers were smoking (≥ 5 cigarettes/day) during the pregnancy