Most medical recommendations for
female scuba divers are based on data from
fit young men and animals, not from
menstruating, menopausal, or pregnant
women, and there is little documentation
about whether diving might disturb the menstrual cycle or whether diving poses
increased risks for menstruating women. Comparative studies between males
and females have attempted to assess the relative risk of DCS, but the results have
differed. On a recent examination of the Divers Alert Network (DAN) database,
however, researcher D. Doyle found that women taking oral contraceptives were
more likely to experience DCS if they dived while menstruating. (Doyle D, et al.,
Menstruation as a risk factor for DCI in female scuba divers taking oral contraceptives.
Undersea Hyperbaric Med 1997; 24 (Suppl): 33.)
The Diving Disease Research Centre in Britain is also conducting a
  major study on “Scuba Diving and the Menstrual Cycle” to determine
  whether there is a correlation between incidents of DCS and female divers’
  menstrual cycles. The study records information about each woman’s
  menstrual cycle along with depth/diving profiles and any dive incidents
  experienced. They are also investigating the impact hormone replacement
  therapies may have on diving.  
Preliminary data shows that 48% of women noticed that diving
  affected their cycle or that the cycle had an impact on their ability to
  dive safely. Fifteen percent felt exercise affected their cycle, 18% said
  diving affected the heaviness of their periods, and 20% reported that
  menstruation had an effect on the pain they experienced when diving.
  So far the study, which will continue for another two years, has collected
  data from 956 women ranging from 14-69 (mean age 35) who collectively
  recorded 199,861 dives.  
Female divers with HRT implants may participate in the study by
  contacting Jane Pimlott at Janep@ddrc.org.