In one of my previous proffesstions I did some time as an instructor at a program that taught survival. Several women who were training to become aircrew or flight nurses attended the couse (little bit of irony there). One of the things we always told them, I don't have first hand experiance obviously, was that they should expect to miss their monthly cycles. Aparently high stress environments combined with the expected weight loss can cause this to happen. It was a point we stessed for them to expect in the class because panic in a survival situation is a death sentance. Still during our 15 day practical exercise we would have a lot of students request sick call for a pregnancy test. Of course, that could have had something to do with the high number of male paratroopers who also attended the course.

Not trying to rule anything out. Just something to keep in mind.

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"Malinois... It's kinda like a bullet. Only it has four legs, teeth, goes around corners, jumps over obsticles, and never misses."

- The DogFather