Question: why do girls have periods pains???!

Laurence Perreault Levasseur answered on 14 Jun 2014:

That is a really good question. I’ve been wondering that many times (about once a month, to be precise), but I never actually looked for an answer. I never took a lot of biology, so I didn’t know, but then I just went on wikipedia and started to read about it. Apparently (except for serious cases where it comes from a more serious condition), it comes from the fact that when the uterus contracts to push the uterine lining and the menstrual fluids out (that’s just the blood girls loose during the periods), the contractions are so strong that some parts of the tissues of the uterus don’t get enough oxygen because the blood can’t pass through (something called ischemia), and that’s what causes the pain. There is an hormone called prostaglandins that tells the uterus how much to contract, and some girls have too much of it, so they get loads of pain because of that.