The aim of the present study is to evaluate whether PFMT can reverse and prevent further development of POP. The project comprises a RCT (main study). In addition we will conduct a case-control study to investigate risk factors, such as muscle strength and joint flexibility in women with and without POP. The project description below will focus on the RCT. The same measurements will be used in the case-control study, and women participating in the RCT will be cases of the case-control study.