Access to appropriate facilities for menstrual hygiene and management (MHM) is recognized as a neglected need within the sanitation sector globally. However, little is known about the magnitude or trajectory of this need. Further, the particular services and facilities required to meet MHM needs depend on the practices and products employed by women and girls. We use nationally representative data from 58 low and lower-middle income countries to estimate that 800 million women in such countries menstruate regularly. Positive correlations between menstruation and nutritional status, as well as menstruation and household wealth, imply a growing need for menstrual management solutions as poverty declines, but both effects are dwarfed by the impact of declining fertility rates. Data on imports of disposable menstrual products reveal exponential growth in their use in low and especially lower-middle income countries. This trend is likely to continue as incomes grow and markets develop, making ever greater the need for provision of appropriate disposal facilities.