Cigarette smoking during pregnancy in rural Nepal. Risk factors and effects of β-carotene and vitamin A supplemention

Objective: We examined risk factors of smoking and the association between smoking and pregnancy-related and 6-month infant mortality in rural Nepal, where 30% women reported smoking during pregnancy. Design: Cross-sectional analysis of risk factors associated with smoking status and health consequences of smoking, using prospective data collected as part of a randomized community trial to examine the effect of maternal vitamin A or β-carotene supplementation on maternal mortality. Setting: Rural, southeastern plains of Nepal. Subjects and methods: A total of 17 767 women contributed at least one pregnancy during 3.5y of the study. Data on cigarette or bidi (rolled tobacco) smoking were collected using a 7-day recall, twice during pregnancy. Associations between smoking status and maternal diet, morbidity profile, household socioeconomic status and serum concentration of retinol, carotenoids and tocopherols were examined. Further, relative risk (RR) and 95% confidence intervals (CI) were calculated to estimate supplement effects on pregnancy-related mortality, stratified by smoking status during pregnancy. Results: Smokers were more likely to be older, illiterate and poor compared to nonsmokers. Fruit and vegetable consumption among smokers and nonsmokers did not vary. However, smokers were more likely to consume meat/fish/eggs and less likely to consume milk than nonsmokers. They were also more likely to report symptoms of vaginal bleeding, edema, severe headache and convulsions during pregnancy relative to nonsmokers. Mortality per 100 000 pregnancies appeared to be higher among smokers than nonsmokers in the placebo group (915 vs 584, RR = 1.57, 95% CI: 0.80-3.08). β-Carotene supplementation reduced pregnancy-related mortality both among smokers (RR = 0.31 95% CI: 0.11-0.89) and nonsmokers (RR = 0.41, 95% CI: 0.19-0.89). Similar results obtained with vitamin A supplementation were not statistically significant. Infant mortality up to 6 months was ∼ 30% higher among smokers compared to nonsmokers in the placebo group both before and after adjusting for confounding factors. Neither supplement given to women reduced infant mortality. Conclusions: Cigarette smoking during pregnancy is associated with an increased risk of maternal and infant mortality in rural Nepal. β-Carotene and to some extent vitamin A may reduce the risk of pregnancy-related mortality, but not infant mortality, among both smokers and nonsmokers.