I think many women around today know about , unlike the past times, but due to lack of research, many women still don't know about menstrual irregularities. So today, I am going to talk about PCOS and menstrual irregularities. Polycystic ovary syndrome (PCOS) is a hormonal disorder that causes enlargement of ovaries with small cysts on the outer edges. Even today, the exact cause of polycystic ovary syndrome is unknown, but includes a combination of genetic and environmental factors.