Hello and thank you for the question! There are a lot of reasons why women do feel pain during periods,but the most important reason is:prostaglandins,which are chemicals produced by womens body.Women who have high level of prostaglandins,may have more pain and discomfort,beacuse prostaglandins stimulate the uterine muscles to contract.Other causes of pain are:ovarian cyst,Infections in the reproductive organs,endometriosis,fibroids etc.Also,a woman that has never been pregnant,is more likely to experience pain.I would advice you to avoid alcohol and smoking and to lose weight if you are overweight,because it may help to reduce pain!If you realise that your menstrual periods are heavy and the pain is getting stronger,you can consult your doctor and have an abdominal echo! Best regards!