Effects of maternal smokeless tobacco use on selected pregnancy outcomes in Alaska Native women: a casecontrol study

Objective To examine the potential effects of prenatal smokeless tobacco use on selected birth outcomes. Design A population-based, casecontrol study using a retrospective medical record review. Population Singleton deliveries 19972005 to Alaska Native women residing in western Alaska. Methods Hospital discharge codes were used to identify potential case deliveries and a random control sample. Data on tobacco use and confirmation of pregnancy outcomes were abstracted from medical records for 1123 deliveries. Logistic regression was used to examine associations between tobacco use and pregnancy outcomes. Adjusted odds ratios (OR), 95% confidence intervals (95% CI), and p-values were calculated. Main outcomes measures Preterm delivery, pregnancy-associated hypertension, and placental abruption. Results In unadjusted analysis, smokeless tobacco use was not significantly associated with preterm delivery (OR 1.44, 95% CI 0.972.15). After adjustment for parity, pre-pregnancy body mass index, and maternal age, the point estimate was attenuated and remained non-significant. No significant associations were observed between smokeless tobacco use and pregnancy-associated hypertension (adjusted OR 0.92, 95% CI 0.561.51) or placental abruption (adjusted OR 1.11, 95% CI 0.532.33). Conclusions Prenatal smokeless tobacco use does not appear to reduce risk of pregnancy-associated hypertension or to substantially increase risk of abruption. An association between smokeless tobacco and preterm delivery could not be ruled out. Components in tobacco other than nicotine likely play a major role in decreased pre-eclampsia risk in smokers. Nicotine adversely affects fetal neurodevelopment and our results should not be construed to mean that smokeless tobacco use is safe during pregnancy.