<prompt> The progesterone component of oral contraceptive pills acts by :Preventing ovulationInhibiting implantationBringing about alterations in cervical mucusAll of the above  <response>: Action of OCPs: 1.The combined oral pill suppresses pituitary hormones,FSH and LH peak and through their suppression prevents ovulation. 2.Progestogen causes atrophic changes in the endometrium and prevents nidation. Progestogen also acts on the cervical mucus making it thick and tenacious and impenetrable by sperms. 3.It also increases the tubal motility, so the feilized egg reaches the uterine cavity before the endometrium is receptive for implantation. Ref: Shaw Gynecology 17 e pg 264. 