<prompt> The progestogenic emergency contraceptive pills act by:Altered cervical secretionInhibition of ovulationAnti-implantation effectInhibition of LH secretion  <response>: The postcoital pill may dislodge a just implanted blastocyst or may interfere with implantation because endometrium is made either hyperproliferative or hypersecretory or atrophic. If it is not the case of emergency contraception, then progesterone could act by increasing the cervical mucus viscosity Ref.Essentials of medical pharmacology TD Tripathi 7th edition page no.324 