The second mechanism is that of thickening the cervical mucus. This third mechanism is abortion. Birth control pills work in two ways. They are a product that contracepts and aborts. The section of each passage that is in bold is the abortive mechanism.
Endometrium is another word for the lining of the uterus.
Any time the word implantation is used this is referring to an already fertilized egg or a new human being. Page numbers are given. Combination oral contraceptives act by suppression of gonadotropins. Although the primary mechanism of this action is inhibition of ovulation, other alterations include changes in the cervical mucus, which increases the difficulty of sperm entry into the uterus, and changes in the endometrium which reduce the likelihood of implantation. These data suggest that the morphological changes observed in the endometrium of OC users have functional significance and provide evidence that reduced endometrial receptivity does indeed contribute to the contraceptive efficacy of Ocs.