Mirror of Justice

A blog dedicated to the development of Catholic legal theory.
Affiliated with the Program on Church, State & Society at Notre Dame Law School.

Monday, February 27, 2006

Elizabeth Brown (St. Thomas Law School) on Plan B

I received several helpful e-mails providing more information on the distinction between contraception and abortifacients.  They generally agreed on the following information, which I received from Elizabeth Brown, and thought I'd post here (thanks also to Denise Hunnell, MD, who sent along very similar information):

While everyone agrees that an abortion is the termination of a pregnancy, the problem is that everyone does not define when pregnancy begins in the same way.  The American Medical Association defines pregnancy as beginning when a fertilized egg implants in the uterus.  Other groups, like the Catholic Church, define life and pregnancy as beginning when the sperm fertilizes the egg.    

Plan B or the morning after pill is like taking two or three regular birth control pills at once.   Generally, Plan B is taken in two doses within 12 hours of each other.  Like regular birth control pills, it can prevent ovulation, or it can prevent the fertilization of the egg, or it can prevent a fertilized egg from implanting in the uterus.  Plan B cannot disrupt or end an established pregnancy, i.e., it doesn’t have any effect if the fertilized egg has implanted in the uterus.  Plan B only works if it is administered 72 hours after having unprotected sex.  If taken within 24 hours, Plan B has a 95% success rate at preventing pregnancy.  The later in that period that a woman begins taking it, the less effective it is.  If begun within 48-72 hours, it only has a 58% success rate at preventing pregnancy. 

As noted above, the American Medical Association defines pregnancy as beginning when a fertilized egg implants in the uterus.  As a result, the AMA does not view Plan B as an abortifacient because it is not terminating an established pregnancy (as the AMA defines pregnancy).  See AMA House of Delegates resolution opposing the FDA’s decision not to allow Plan B without a prescription.


Many groups opposing Plan B view any fertilized egg as a human being and thus, any chemical that prevents a fertilized egg from implanting is, in their definition, an abortifacient.

Plan B is different from RU-486, or the abortion pill, which is administered 4-7 weeks into a pregnancy and is designed to terminate the pregnancy.  In the case of RU-486, everyone agrees that a viable pregnancy exists and will end if RU-486 is administered.

Not every woman, who has unprotected sex and does not use contraceptives, will become pregnant.  In addition, about 40-60% of fertilized eggs naturally fail to implant on their own.

At this point in time, there is no way for anyone to know whether unprotected sex has resulted in a fertilized egg or not because pregnancy tests can only detect an implanted fertilized egg.  So neither the woman taking Plan B nor the doctor prescribing Plan B nor the pharmacist dispensing Plan B can know for certain that the medication will, in fact, terminate a fertilized egg, instead of merely preventing ovulation, preventing fertilization, or doing nothing.

For more information on Plan B, see http://www.uspharmacist.com/index.asp?show=article&page=8_1567.htm

In general, Plan B may be viewed as being a bit like Russian Roulette.  There is a very small chance that it will, in fact, terminate a fertilized egg compared to the chance that it will prevent ovulation or fertilization or do nothing.  If it prevents ovulation or fertilization then it is no different that any other contraceptive. 


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