Smoking during pregnancy presents health risks for both the mother and her child. In this study we followed changes in the production of steroid hormones in pregnant smokers. We focused on changes in steroidogenesis in the blood of mothers in their 37(th) week of pregnancy and in mixed cord blood from their newborns. The study included 88 healthy women with physiological pregnancies (17 active smokers and 71 non-smokers). We separately analyzed hormonal changes associated with smoking according to the sex of newborns. In women with male fetuses, we found higher levels of serum cortisone, dehydroepiandrosterone (DHEA), 7alpha-OH-DHEA, 17-OH pregnenolone, testosterone, and androstenedione in smokers at the 37(th) week compared to non-smokers. In women with female fetuses, we found lower serum levels of 7beta-OH-DHEA and higher androstenedione in smokers at the 37(th) week. We found significantly higher levels of testosterone in newborn males of smokers and higher levels of 7alpha-OH-DHEA in female newborns of smokers. Smoking during pregnancy induces changes in the production of steroids in both the mother and her child. These changes are different for different fetal sexes, with more pronounced changes in mothers carrying male newborns as well as in the newborn males themselves.