Background: 91% of those who menstruate reported to experiencing associated pain. Despite the ubiquity of this phenomenon, the prevalence, extent and socio-demographic variation of menstrual pain remains understudied at national levels - whether due to a shortage of applicable data at national scales or other factors.Method: We assess the extent and variation of menstrual pain at a national level. To achieve this, we develop a novel proxy measure for menstrual pain, utilising behavioural data extracted from mass s…