Over 50% of those engaging in high altitude activities are women.1 Nonetheless, women have historically been neglected in scientific literature regarding backcountry environments. Acute mountain sickness (AMS), a condition triggered by hypoxia, is common at altitudes >2500 m above sea level, and prior studies suggest that women are particularly vulnerable to it due to hormonal changes associated with menstruation.2–4 Therefore, this study assessed the association of menstruation and AMS incidence during a high-altitude expedition to Mount Kilimanjaro.

This retrospective study involved a review of records from the Equal Playing Field expedition, in which 48 female athletes trekked to the summit of Mount Kilimanjaro via the Shira route (5895 m) to set a world record for the highest altitude soccer match. One emergency medicine physician with altitude experience served as Chief Medical Officer along with two wilderness emergency medical technicians. The medical team conducted ‘rounds’ in the mountain camp …