Clearly, females have a higher incidence of anterior cruciate ligament (ACL) tears. The reasons for this may be multifactorial and not just one cause. For example, differences in male versus female anatomy may be a big part of the problem. The width of the pelvis and the angle at the knee are just a couple things to consider.
Training techniques and training schedules may also be a factor. As a coach, you may have more to say about this variable than things you can't change like body type or hormone levels.
Monthly fluctuations of hormones can affect ligaments. Exactly how the collagen fibers are affected hasn't been shown yet. It's possible the fibers relax more during certain times of the month, making them more vulnerable to injury. There is an actual hormone called relaxin designed to relax soft tissues during pregnancy and birth. It's possible that levels of relaxin rise and fall with the menstrual cycle.
There are no specific guidelines at this time to put into action. More research is needed because studies have not consistently shown the same results when hormone levels have been tested in athletes.