Effects of maternal smokeless tobacco use on selected pregnancy outcomes in Alaska Native women: a case-control study.

OBJECTIVE: To examine the potential effects of prenatal smokeless tobacco use on selected birth outcomes. DESIGN: A population-based, case-control study using a retrospective medical record review. POPULATION: Singleton deliveries 1997-2005 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 0.97-2.15). 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 0.56-1.51) or placental abruption (adjusted OR 1.11, 95% CI 0.53-2.33). 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.

Maternal smokeless tobacco use in Alaska Native women and singleton infant birth size.

OBJECTIVE: To examine the effects of maternal prenatal smokeless tobacco use on infant birth size. DESIGN: A retrospective medical record review of 502 randomly selected deliveries. POPULATION AND SETTING: Singleton deliveries to Alaska Native women residing in a defined geographical region in western Alaska, 1997-2005. METHODS: A regional medical center's electronic records were used to identify singleton deliveries. Data on maternal tobacco exposure and pregnancy outcomes were abstracted from medical records. Logistic models were used to estimate adjusted mean birthweight, length and head circumference for deliveries to women who used no tobacco (n=121), used smokeless tobacco (n=237) or smoked cigarettes (n=59). Differences in mean birthweight, length and head circumference, 95% confidence intervals and p-values were calculated using non-users as the reference group. MAIN OUTCOME MEASURES: Infant birthweight, crown-heel length and head circumference. RESULTS: After adjustment for gestational age and other potential confounders, the mean birthweight of infants of smokeless tobacco users was reduced by 78 g compared with that of infants of non-users (p=0.18) and by 331 g in infants of smokers (p<0.01). No association was found between maternal smokeless tobacco use and infant length or infant head circumference. CONCLUSIONS: We found a modest but non-significant reduction in the birthweight of infants of smokeless tobacco users compared with infants of tobacco non-users. Because smokeless tobacco contains many toxic compounds that could affect other pregnancy outcomes, results of this study should not be construed to mean that smokeless tobacco use is safe during pregnancy.