Why do you sometimes have cramps when you have your period?

Answer

The cramps you may experience during your period are caused by contractions of the uterus. When a uterus (which is just a muscle) contracts, the surrounding organs such as bladder and bowel may contract as well. The substances that the uterus produces when it contracts (prostaglandins) can stimulate those organs and can also cause headaches, for example.

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