why do we get period cramps

Period cramps, also known as dysmenorrhea, happen primarily because of a chemical called prostaglandin that is released by the uterus before and during menstruation. Prostaglandins cause the muscles of the uterus to contract tightly; these contractions help shed the uterine lining, which is the bleeding during the period. However, when these contractions are very strong, they can temporarily reduce blood flow and oxygen to the uterus, causing pain and cramping sensations that are felt in the lower abdomen and sometimes in the back or thighs. The levels of prostaglandins rise just before menstruation starts, which is why cramps usually begin 24 to 48 hours before the period and then ease after a few days once the period starts. Some people experience more painful cramps than others, possibly due to higher levels of prostaglandins or differences in individual bodies. Additionally, certain conditions like endometriosis, fibroids, or pelvic inflammatory disease can cause secondary dysmenorrhea, which leads to more severe or prolonged cramps. Other factors that may increase the risk of painful cramps include early puberty, heavy menstrual bleeding, smoking, and being under age 30. In summary, the core reason for period cramps is the action of prostaglandins inducing uterine muscle contractions to shed the lining, with pain resulting from the strength of these contractions and temporary lack of oxygen supply to uterine muscles.