<prompt> All of the following mechanisms might account for a reduce-risk of upper genital tract infection in users of progestin - releasing lUDs, except:Reduced retrograde menstruationDecreased ovulationThickened cervical mucusDecidual changes in the endometrium  <response>: Decreased ovulation does not protect from upper genital tract infection. Also it doesnt inhibit ovulation in all women. THE TEXTBOOK OF GYNAECOLOGY SHEILA BALAKRISHNAN SECOND EDITION PAGE NO 379 