Clip 'n' save 'n' quote frequently.
This is the relevant portion of the abstract of a peer-reviewed paper (meaning here: actual science) from the American Journal of Obstetric Gynecology that was designed to evaluate the familiar claim of the anti-contraception camp that oral contraceptives prevent the implantation of the fertilized egg in the uterus, and thus are nothing more than little abortion 21-packs. This is the "reasoning" behind the new Health and Human Services proposal that all healthcare workers receiving federal monies be allowed to refuse to administer said contraception under an expanded and even more insidious conscience clause than we've already had to deal with regarding pharmacies.
The one little problem with the "pills kills babies" argument is that it's patently false. As Christina Page explains over at HuffPo, the pill works by preventing ovulation, and on the very small chance that an egg manages to wriggle out of the ovary despite a hormonal bombardment that will keep it lodged in there 'til the cows come home, secondary hormonal safeguards are in place to make it very difficult for sperm to slog their way to the egg through thickened mucous on the vaginal walls, and then, if an exhausted sperm or two stagger up to the egg more exhausted than salmon whose ladders up the falls have been removed for painting, the lining of the egg itself will refuse to cooperate with them. In other words, if you use the pill there will almost certainly be no egg, and if there is an egg it won't get fertilized.
But, the anti-contraceptioneers will whinge, what if three individually statistically unlikely events all happen, even more statistically unlikely, all at the same time and there is an egg and there is a sperm and they hook up and create a zygote? Well, if all that happens, it's probably going to implant at the same rate as any other fertilized egg, which is roughly 50% of the time. Progestin acts to maintain the endometrium, which is the exact opposite of a hostile environment for the egg, so if those three unlikely events all occur (four if you count the even odds of a fertilized egg burrowing into the uterine wall and sticking), there's no evidence to suggest that implantation will be hindered at all.
Plan B, the morning-after pill, works exactly the same way because it's exactly the same hormone, simply at a higher dosage. PZ Myers explains in detail here. Plan B is a wing and a prayer because it only works if you haven't already ovulated. If an egg is lurking in the vicinity of your fallopian tubes when a load of semen gets dumped into your vagina, Plan B will not keep the egg from getting fertilized, and will not keep it from implanting in your uterine wall and setting you off on the exciting adventure of deciding what next.
In neither case does the oral contraceptive in question come close to creating an abortion. The anti-choice camp's refusal to let go of their cherished folk belief that fertilized egg = fully formed human being ==> birth control = abortion is now threatening to corrupt public health policy at the highest level. Don't let people continue to cling to fears that have no basis in science.