The progestogenic emergency contraceptive pills act by:
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)
Altered cervical secretion
Inhibition of ovulation
Anti-implantation effect
Inhibition of LH secretion
Endocrinology