Exposure to ETS (environmental tobacco smoke) is one of the most toxic environmental exposures. To investigate the association of ETS with physiological, biochemical, and psychological indicators, as well as with urine antioxidant capacity (AC) and oxidative damage to lipids in a pilot sample of healthy pregnant women. Exposure to ETS was investigated via a validated questionnaire, and urine cotinine and the marker of oxidative damage to lipids via 8-isoprostane concentrations using an ELISA kit. Urine AC was determined by the spectrophotometric Trolox-equivalent antioxidant capacity (TEAC) method. From a sample of pregnant women ( = 319, average age 30.84 ± 5.09 years) in 80, the levels of cotinine and oxidative stress markers were analyzed. Among the 80 pregnant women, 5% (7.4% confirmed by cotinine) reported being current smokers and 25% reported passive smoking in the household (18.8% confirmed by cotinine). The Kappa was 0.78 for smokers and 0.22 for ETS-exposed nonsmokers. Pregnant women in the ETS-exposed group had significantly reduced AC compared to both the nonsmoker (ETS-) and the smoker groups ( < 0.05). Nonsmokers had significantly lower levels of 8-isoprostane than smokers ( < 0.01) and ETS-exposed nonsmokers ( < 0.05). Correlations between urine levels of cotinine and AC were positive in ETS-exposed nonsmokers. A harmful association of active and passive smoking and oxidative stress parameters among pregnant women has been indicated.