Basically it's A monthly cleansing of your euterus in preparation for pregnancy. The cramps are actually contractions of the euterine muscles much like you experience in labor. I'm not sure why it has to happen monthly and for so long. I hated my period for the first half of my life because I didn't understand it. It makes more sense now. The more you learn the intricacies of your cycle the more you appreciate it.
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