Background: Pregnancy is a physiological process associated with an excessive oxidative stress for both the mother and the neonate. Oxidative stress was extensively studied and is still in focus as a factor of maternal pathologies during pregnancy, with consequences on the outcome of the neonate. Aim: The aim of our study was to determine whether oxidative stress-related factors can influence the outcome of pregnancy, delivery, and the neonate’s wellbeing. Material and methods: The study was conducted using a questionnaire among pregnant women with voluntary enrollment. Exclusion criteria were preeclampsia or other cardiovascular diseases, gestational diabetes, and hypothyroidism at admission. Patients were enrolled in a control group of 60 pregnant women without preexisting pathology and pregnancy with physiological course, a premature group of 21 pregnant women with premature delivery, and a cardiac group of 8 pregnant women with fetal heart disease known before birth. The study population was separated into subgroups based on dietary supplement use within the three main groups, and other subgroups for smoking/non-smoking mothers in the control group and one for smoking/non-smoking mothers in the premature and cardiac groups together. Results: The mean Apgar score at 1 minute was significantly higher in the control group compared to the cardiac group (p = 0.0023). The 1-minute Apgar score was significantly lower in infants that were born premature, from smoking mothers, compared to babies that were delivered at term (p = 0.0191). Although we did not obtain significant differences in birth weight corrected by gestational age between the control (mature) group and premature group, there was a good correlation in gestational age and birth weight of the preterm born infants (r = 0.8517, p <0.0001). Conclusions: Smoking can aggravate oxidative stress in pregnancy, which will contribute to a difficult postnatal adaptation of newborns from smoking mothers and will increase the risk of premature delivery.