Placental Hypoxia and Oxidative Stress Responses to Smokeless Tobacco Use in Alaska Native Participants in the MAW Study

Cigarette smoking is associated with numerous adverse pregnancy outcomes, due in part to polycyclic aromatic hydrocarbons and free radicals produced by combustion. Less is known about the impact of smokeless tobacco (ST) use during pregnancy. Alaska Native women report higher rates of cigarette and ST use during pregnancy than non-Native women. We investigated oxidative stress and hypoxia pathways in term placentae from Alaska Native women who did (commercial or iqmik; n=10) or did not (n=18) use ST during pregnancy. Despite substantial maternal exposure to nicotine, placentae of women who used ST had similar mRNA levels of antioxidant enzymes and markers of hypoxia compared to those who did not use tobacco. Although mRNA levels of angiogenesis markers vegf and vegfr2 were similar between groups, vegfr1 mRNA levels are increased in placentae of women using ST compared to women who did not use tobacco. Together these results suggest that, while ST use may not have as significant an effect on oxidative stress pathways in the placenta as cigarette smoking, an effect is present. It is not clear what this limited effect may have on the developing fetus.