All of the following mechanisms might account for a reduce-risk of upper genital tract infection in users of progestin - releasing lUDs, except:
Decreased ovulation does not protect from upper genital tract infection. Also it doesn't inhibit ovulation in all women. THE TEXTBOOK OF GYNAECOLOGY SHEILA BALAKRISHNAN SECOND EDITION PAGE NO 379
Reduced retrograde menstruation
Decreased ovulation
Thickened cervical mucus
Decidual changes in the endometrium
Contraception