BackgroundTo estimate Population Attributable Fractions (PAFs) and Generalized Impact Fractions (GIFs) for LBW following scenarios to remove or decrease prenatal use of caffeine or water pipe.MethodsUsing data of 861 pregnant women from a population-based prospective cohort study in suburbs of Bandar Abbas city (2016-2018), PAFs and GIFs were calculated based on the relative risk scale. Practical interventional scenarios to reduce the exposure prevalence were developed for calculation of GIFs. ResultsThe cumulative incidence of LBW was 16.1%. An estimated 19% (95%CI: 6, 30%) of LBW neonates was attributed to dietary caffeine intake of >100 mg/day and 11% (95%CI: 8,14%) to water pipe smoking. Action plans to reduce caffeine intake and water pipe smoking suggested an avoidable burden of LBW cases of approximately 10.7% (95% CI: 6.6, 25.3%) and 5.7% (95%CI: 5.0, 6.8%), respectively.ConclusionsWater pipe smoking and excessive consumption of caffeine during pregnancy decreased birth weight. Practical action plans to control water pipe smoking and to prevent excessive intake of caffeine among pregnant women would substantially reduce LBW burden in the south of Iran.