Why do women have menstrual pains? What causes them?

Answer:
When a woman goes through her menstrual cycle different hormones help to prepare the egg for implantation in the woman's uterus (endometrium lining). The egg is implanted and waits to be fertilized by a sperm cell, if it is not the woman at about midway through the cycle releases not only the egg but a layer of the uterus the matured with nutrients to sustain the egg. So I guess you can look at a period as giving birth to thelining and an unfertilized egg. The pain can be coming from the minor contractions necessary to release the layer of uteral lining.

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Not exactly sure, but its to do with the way the muscles contract and un-contract. Damn muscles!!

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Menstrual pain is due to contractions or spasms of the uterine muscles, triggered by the drop in hormones estrogen and progesterone. The uterus is triggered to shed the lining which has been built up during the previous 28 days or so, which is done by spasms that cause it to slough off. In some women these spasms or contractions are strong enough to cause discomfort and pain, sometimes severely enough to cause nausea and vomiting. Cramps, as they are called, are treated with ordinary muscle relaxants, which serve to calm the uterine muscles.

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Basically a woman cramps because her uterus is contracting to help shed the uterine lining.

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