Relationship of menstrual history to altitude chamber decompression sickness.

Records at the USAF School of Aerospace Medicine, Division of Hyperbaric Medicine, were reviewed to determine the relationship between the incidence of altitude chamber decompression sickness (DCS) in females and menstrual history. The study period spans 11 years, from January 1978 to December 1988. There were 81 records suitable for study. A significant inverse linear correlation was noted between the number of days since the start of last menstrual period and the incidence of DCS. This relationship was noted with both Type I and Type II DCS. Lack of information on the population at risk precluded an analysis of the effects of birth control pills on this phenomenon. The underlying mechanism for the correlation between menstrual cycle and susceptibility to development of DCS is unknown. We conclude that women are at higher risk of developing altitude related decompression sickness during menses, with the risk decreasing linearly as the time since last menstrual period increases.