Amidst an ongoing debate among prolife advocates about whether to classify the Pill as an abortifacient or a prophylactic, pro-abortion advocates have published an authoritative statement declaring that the Pill prevents implantation of embryos, thereby causing an abortion. 
More Information:
Life Site News is reporting that in a supplement to its November 2008 issue, top reproductive health journal Fertility and Sterility published the American Society for Reproductive Medicine (ASRM) statement, “Hormonal contraception: recent advances and controversies.” 
In a summary of the development of contraception in the United States the statement called oral contraceptives the “most widely used” reversible method.  In the “wide variety” of oral contraceptives that are available, the “mechanisms of action” are the same, said the statement: “inhibition of ovulation, alteration in the cervical mucus, and/or modification of the endometrium, thus preventing implantation.”  
Pro-life advocates who oppose abortion, but not contraception, have long considered the Pill as an ethical contraceptive option, as opposed to the IUD, which causes abortions by preventing implantation.  However, the statement by the ASRM clearly indicates that the pill is medically classified as a drug that acts by “preventing implantation,” thereby causing the death of a fertilized embryo – a unique and living human being.   
A large body of literature supports this statement, including articles from Fertility and Sterility.  The most significant of these is a 1996 study by a group of OB/GYNs from the University of North Carolina, Chapel Hill, that concluded that “impaired uterine receptivity” is “one mechanism by which OCs exert their contraceptive actions.”
This report basically repeats what Dr. Joe Stanford found in our systematic review on the topic: Postfertilization Effects of Oral Contraceptives and Their Relationship to Informed Consent (Arch Fam Med. 2000;9:126-133). You can read the article here. 
I’ve commented on how this information changed my beliefs and practice. You can read that commentary here. I’ve also written an article about the ethics of this issue, The Growing Debate About the Abortifacient Effect of the Birth Control Pill and the Principle of the Double Effect. You can read that article here.   
This report kinda makes pro-life organizations (especially those with physician input) who have supported the pill as NOT being an abortifacient look a bit silly (at least in my opinion). 
Worse yet, how many unborn children have been lost during this so-called debate?
The only folks in the whole world who seem to be holding to the fixed false belief (psychiatrists call a fixed-false belief a delusion) that the BCP does not, at times, cause the unrecognized death of an unborn child by preventing implantation are some Christian ob-gyns and family physicians. 
The secular community has almost with a 100% consensus said what this new report says, “In the ‘wide variety’ of oral contraceptives that are available, the ‘mechanisms of action’ are the same, said the statement: ‘inhibition of ovulation, alteration in the cervical mucus, and/or modification of the endometrium, thus preventing implantation’.”  
To me, until the BCP is shown NOT to have an abortifacient effect, it’s time for Christian physicians,  ethicists, and pro-life organizations to stand up and say “tie goes to the unborn baby.” 
We can no longer afford to risk the lives of the unborn for the supposed convenience of women or their Christian physicians – especially since modern, scientific natural family planning techniques are as or more effective than the BCP and do not have an abortifacient effect.
You can read more about this topic by looking at a reading list I’ve compiled, here.