The Rhythm Method May Cause More Embryonic Deaths Than Some Other Contraceptives
Contraception poses an ethical dilemma for many people. Questions about when life begins, what defines a human being, the rights of parents, and the role of government and the church complicate the issue. There are several types of birth control including abstinence, methods that prevent fertilization from occurring, and methods that prevent a fertilized egg (called an embryo) from implanting in the wall of the uterus. The rhythm method is a timing technique that depends on abstinence from sexual intercourse on the days during a woman’s menstrual cycle when she is most fertile.
The rhythm method is believed to work by preventing fertilization from occurring. For this reason, pro-life advocates view the rhythm method as an acceptable form of contraception. The Catholic Church also condones this method because it doesn’t interfere with conception. However, in this week’s
Journal of Medical Ethics
, an author argues that the rhythm method could actually be responsible for many more embryonic deaths than some other contraceptive methods.
About the Study
Professor Luc Bovens, of the London School of Economics and Political Science, uses several plausible assumptions to detail his case regarding the rhythm method’s role in embryonic deaths. He suggests that the rhythm method works not because it prevents conception, but because the embryos conceived have limited ability to survive. These embryos, conceived during the few days before or after the period of abstinence are more fragile than those created in the middle of the fertile period. The uterus is less hospitable to these embryos during this time period as well.
Professor Bovens used mathematical calculations to show that for every rhythm method pregnancy, there are three or four embryonic deaths. If his assumptions are correct, millions of “successful” rhythm method cycles each year depend on the death of a great many embryos.
The major limitation of Boven’s argument is that it is based on number assumptions, rather than verified observations. It is not known whether the rhythm method is more often successful because it prevents conception or because an embryo dies. There is also a lack of evidence about the degree to which embryos are less viable when conceived on the fringes of a woman’s fertile period.
How Does This Affect You?
No contraception technique, with the exception of abstinence, is foolproof, but the rhythm method is less reliable than some other techniques. If it is followed perfectly (which is rarely the case), the rhythm method is about 90% effective; in other words, one woman out of ten will become pregnant in an average year. But typically, the technique is far less effective. The rhythm method may be natural, but it is not effortless, and is not appropriate for all women. It requires consistent monthly periods, a cooperative partner, a willingness to learn the method and practice it, and an acceptance of the risk of pregnancy.
If you wish to practice birth control, be sure to research and evaluate your options based on personal preference, religious beliefs, comfort and ease of use, reliability, and reversibility. Many factors must be considered when choosing a contraception method, and your doctor can help answer your questions and sort through your concerns before making a choice.
Merck Manual Home Edition
Planned Parenthood Federation of America, Inc.
US Food and Drug Association (FDA)
Birth Control Guide (updated December 2003)
Bovens L. Rhythm method and embryonic death.
J Med Ethics
. 2006; 32:355-356.