In this survey, socio-economic status of pregnant women smoking during pregnancy and influence of this status on birth weight of their newborn were assessed. The research was done on the group of 1328 pregnant women. Smoking habit was declared by 18.6% of women and passive exposure to tobacco smoke was stated by 30.6% of respondents. Significant association between active and passive smoking and socioeconomic status of respondents was observed. Cigarette smoking during pregnancy was the main cause of lower birth weight of newborns. The newborns of actively smoking mothers were lighter of about 357 g according to those ones of mothers who did not smoke and were not exposed to passive smoking, and were lighter than newborns of mothers who were not exposed to passive smoking of about 330 g. The passive exposure to the tobacco smoke was not significant considering effect on the birth weight.