Women at Altitude: Effect of Menstrual-Cycle Phase on Acute Mountain Sickness During Deployment to High Altitude Terrain

Abstract

Abstract : The physiologic responses to the cyclic fluctuations in ovarian steroid hormones associated with the menstrual cycle in women are well known to affect certain disease states and could alter responses to environmental stressors. Rapid deployment to high mountain terrain induces acute mountain sickness (AMS), which can be an important source of performance decrements and Disease and Non-Battle Injury loss of personnel in military units. To determine the effect of menstrual cycle phase on the occurrence of AMS, symptoms were assessed in 39 women aged 18 to 33 years with normal menstrual cycles who were expose to 4300 m altitude continuously on the summit of Pikes Peak, CO for 12 days or in a hypobaric chamber for 60 hours during the early follicular (follicular phase group) or luteal phase (luteal phase group) of their menstrual cycle. The clinical course of AMS in these women was similar to that reported previously in men. Overall, more than 60% of the women in this study experienced AMS during the first 24 hours of altitude exposure. There were no statistically significant differences between symptom scores of the follicular and luteal phase groups. However, the prevalence of AMS was slightly lower in the luteal phase compared to follicular phase volunteers. We conclude that effects of menstrual cycle phase are too small to be of practical significance for most women involved in military operations or civilian recreational pursuits at altitudes up to 4300 m.