PRINCETON, New Jersey, Feb. 22, 2013 (LifeSiteNews.com) – The same month that Germany’s bishops have backed the use of the morning-after pill for rape victims, one of the world’s leading authorities on the drug has said doctors have a duty to inform women that it could prevent a newly-conceived embryo from implanting in the womb, causing an abortion.

Dr. James Trussell, Director of Princeton’s Office of Population Research, makes the statement in an academic review on the drug dated February 2013 and co-authored with Dr. Elizabeth G. Raymond.

"To make an informed choice, women must know that [emergency contraceptive pills] … prevent pregnancy primarily by delaying or inhibiting ovulation and inhibiting fertilization, but may at times inhibit implantation of a fertilized egg in the endometrium,” they write.

A senior fellow at the Guttmacher Institute, a member of the Planned Parenthood Federation of America’s national medical committee, and a board member of the NARAL Pro-Choice America Foundation, Trussell has published over 50 academic articles on the morning-after pill and runs a popular website and hotline to promote its use.

For many years, pro-life activists have opposed the morning-after pill, even in cases of rape, because of studies showing the drug acts in some cases as an abortifacient by altering the woman’s endometrium to prevent the embryo from implanting.

But in recent years some studies have suggested there is no such “post-fertilization” effect and that the drug acts only by preventing conception, either by suppressing ovulation or impeding the sperm.

The question of the drug’s abortifacient effect is obviously crucial to pro-lifers who could never support abortion even in cases of rape.

But the question is also important to Catholics and others who oppose contraception, because it bears on the proper treatment of rape victims. While some Catholic theologians argue that contraception is intrinsically evil and therefore never able to be used, others argue that using contraception to prevent a pregnancy following rape is morally acceptable because the aim is to repel the attacker.

On this principle, Catholic hospitals in various dioceses in North America have administered the drug, with the support of the bishops, even though some dioceses have forbidden it.

Where the drug is used by Catholics, generally a test is administered first in the hope of ensuring that an existing pregnancy would not be endangered. But the use of the drug has been hotly contested, with opposition even from a former head of the Pontifical Academy for Life, because of the possibility that even after testing the drug could be abortive.

The controversy within the Church has been reignited in recent weeks after two Catholic hospitals in Cologne reportedly refused treatment to a rape victim because the law required them to administer the morning-after pill.

Cologne’s Cardinal Joachim Meisner issued a statement Jan. 31st supporting the use of drugs to prevent conception after rape and on Thursday the German bishops announced that they made the same determination at their plenary meeting this week.

The German bishops’ statement affirms that “medical-pharmacological methods that cause the death of an embryo still may not be used.”

The Cardinal reportedly issued his statement after reviewing a 2012 study in the journal Contraception showing that the drug is not an abortifacient.

But that study has been called into question because the lead author acknowledges acting as an advisor on the drug to pharmaceutical companies that produce it. The paper itself states that concerns about the abortifacient effect is “one of the main barriers” to a wider distribution of the drug.

In the new review by Trussell and Raymond they note that several studies have found the drug alters the endometrium, suggesting an abortifacient function, but they also indicate that more recent studies like the one in Contraception have found no alterations.

As a result of these more recent studies, they say, some have concluded that there is no post-fertilization effect, but, they add, “others may always feel that this question has not been unequivocally answered.”

While they insist that women be informed of the risk the drug poses to a newly-conceived embryo, Trussell and Raymond also say women should be informed that the “best available evidence” indicates the drug’s effectiveness “can be fully accounted for” by non-abortifacient effects.

The two also make the ludicrous claim that even with a post-fertilization effect the drug is “not abortifacient,” citing the fact that medical authorities define pregnancy to begin at implantation rather than conception.

The pro-life view would hold, however, that that definition is false because biological science affirms that life begins at fertilization.

The academic review by Dr. James Trussell and Dr. Elizabeth G. Raymond can be found here.