Smokeless tobacco consumption and stillbirth: population-based case-control study in rural Bangladesh

Introduction and Aims: To investigate the association between smokeless tobacco consumption (STC) during pregnancy and risk of stillbirth. Design and Methods: We conducted a population-based case-control study of 253 cases and 759 randomly selected control women in Madaripur, Bangladesh. We conducted a survey of two rural local government areas, including 8082 women, and identified cases based on self-report of a stillbirth outcome of each participant's first pregnancy. All were asked about STC during their first pregnancy and a range of risk markers and known confounders. Demographic and maternal variables associated either with stillbirth or STC were included in logistic regression models. Results: Of the 241 cases and 757 controls with complete exposure data, 32 cases (13.2%) and 18 controls (2.4%) reported STC during pregnancy [odds ratio 6.28; 95% confidence interval (CI) 3.45, 11.4]. After adjustment for education, household income, age at first pregnancy, vaccination during pregnancy, complications, exposure to arsenic in drinking water, place of delivery and antenatal care, excess risk was attenuated but remained significant [adjusted odds ratio (aOR) 2.87; 95% CI 1.36, 6.08] . There was a dose-effect association, with women who used smokeless tobacco > 5 times daily during their first pregnancy at greater risk of having a stillbirth (aOR 5.89; 95% CI 1.70, 20.3) than less frequent users (aOR 1.67; 95% CI 0.65, 4.29). Estimates were robust to extreme assumptions about missing exposure data. Discussion and Conclusions: STC during pregnancy was associated with an increased risk of stillbirth. This finding adds to the urgency of need for smokeless tobacco control strategies to be implemented in South Asia.