1 Who's sexual partner is infected. This is the main cause of PID. When the sexual partner is infected or is carring pathogen such as gonococcus or chlamydia, women would be infected. 80% women with PID have infected sexual partner. Men has no symptoms don't indicates that they are health.

2 The younger you are, the more easy it is for you to develop PID. Women between 15 - 19 get a two times higher morbidity than women between 25 - 29. Women between 20 - 24 get a one time higher morbidity than women between 25 - 29. That is probably because the younger women are, the more sex or sexual partner they have.

3 Women who have got a PID before risk for another attack of PID with a 19 times higher rate than health women. 20% - 25% PID sufferers' disease would recur. It is better to regard it as a reinfection rather than regard it as a recurrence. As for the reason, the epithelium of fallopian tubes are already damaged in previous attack of disease, they are more sensitive to pathogens.

4 Women who used to have a gonorrhoea often develop PID. One of the possibilities is that gonococci still exist in the uterine neck which develops no symptoms.

5 Sexual actions are closely associated with PID. Primary PID is commonly caused by sexual actions or sexual exposure. It is not proved that semen is carring pathogen. Homosexuality is not a risk factor of PID. Infection is not related with the frequency of sexual intercourses, but to the number of sexual partners.

6 Women who have IUDs risk for PID with a 3 times higher rate than other women.