Tobacco use is a leading cause of death and of poor pregnancy outcome in many countries. While tobacco use is decreasing in many high-income countries, it is increasing in many low- and middle-income countries (LMICs), where by the year 2030, 80% of deaths caused by tobacco use are expected to occur. In many LMICs, few women smoke tobacco, but strong evidence indicates this is changing; increased tobacco smoking by pregnant women will worsen pregnancy outcomes, especially in resource-poor settings, and threatens to undermine or reverse hard-won gains in maternal and child health. To date, little research has focused on preventing pregnant women's tobacco use and secondhand smoke (SHS) exposure in LMICs. Research on social and cultural influences on pregnant women's tobacco use will greatly facilitate the design and implementation of effective prevention programs and policies, including the adaptation of successful strategies used in high-income countries. This paper describes pregnant women's tobacco use and SHS exposure and the social and cultural influences on pregnant women's tobacco exposure; it also presents a research agenda put forward by an international workgroup convened to make recommendations in this area.