1. Re: The rhythm method and embryonic death

    Dear Editor,

    This is an interesting hypothesis, but the author has lost me in the second paragraph by saying that "rhythm" is the only method approved by the Catholic Church. Whether Bovins has confused rhythm with NFP or presumed the two methods are one and the same, it is an inexcusable error in a scientific report.

    Rhythm is using a calendar, assuming the "standard" 28-day cycle, to guesstimate when ovulation occurs. It is highly fallible, most obviously because very few women actually experience the "textbook" 28-day model for the menstrual cycle promoted as part of the rhythm method.

    Natural Family Planning, or NFP, on the other hand, depends on recognizing certain physical symptoms of fertility and approaching ovulation -- changes in quantity and quality of cervical mucus discharge, the shape, placement and consistency of the cervix itself, and a few more complicated techniques like basal body temperature. It can be used to try to achieve or avoid pregnancy.

    NFP is approved by the Church for use in extraordinary circumstances (couple abstain from intercourse during the time a woman is fertile) because it does not interfere with a woman's natural cycles, because it is consistent with a respect for life, and (this is very important!) because it shows respect for the nature of the marital sexual union as an analogy of the mystical union between Christ and His Church. (People think the Church is anti-sex.... ahhhh, if only they knew!)

    NFP is proven to be more than 98% effective, more effective than any other contraceptive measure. Of course, it involves the inconvenience of paying attention to fertility symptoms and of a degree of self-denial, but it is extremely effective. Moreover, every couple I know who have practiced NFP are enthusiastic advocates of it -- yes, that includes the men, who say that periods of abstinence enrich their elationships with their wives and make the times of intimacy more gratifying.

    Oh -- some studies indicate that NFP couples actually engage in sexual intercourse more times per month than non-NFP couples.

    Finally, I am not comfortable with the promotion of "assumptions" without a presentation of the basis from which said assumptions occur. One can easily dismiss the premise that rhythm leads to more deaths in consequence: embryonic deaths can occur from flaws resulting from unhealthy ovum or sperm (ostensibly because of "old" sperm left in the fallopian tube to fertilize the ovum), but they can also occur because of biochemical hostilities brought about by mechanical and/or chemical impositions of artificial birth control methods. However, the thing Catholic consider is that embryonic deaths due to lack of viability is not the result of a hostile act against life in general or the specific conception. This is of paramount importance.

    I recommend Bovens and anyone else interested in the subject read Kippley and Kippley, The Art of Natural Family Planning, and the Papal Encyclicals: Pope Paul VI's Humanae Vitae and John Paul II's Evangelium Vitae: John Paul II's work on Theology of the Body (synthesized for easier mental consumption by Christopher West) is also seminal.

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  2. Hogwash in the guise of research

    Dear Editor,

    Recently the Journal of Medical Ethics published an article by L Bovens, from the London School of Economics and Political Science, Department of Philosophy, Logic and Scientific Method. Under a banner REPRODUCTIVE ETHICS, the article was entitled The rhythm method and embryonic death. The gist of the article was that the pro-life movement, and particularly Catholics, are responsible for the deaths of “millions of unborn children” by advocating the Rhythm Method.

    The route which Bovens took to arrive at this conclusion offers a circuitous, dual lane and very bumpy ride. Circuitous because it went by way of three assumptions, dual lane because he argued from “science” and “philosophy” , and bumpy because even the basic premise was full of pot-holes.

    “The first assumption is that there are a great number of conceptions that never result in missed menses. There are estimates that only 50% of conceptions actually lead to pregnancies.” Bovens does not favour us with the source of these estimates, but we do know that a study conducted at the Royal Women’s Hospital in Melbourne in 1985/6, debunked this myth. Women who were hoping for a pregnancy were asked to submit to regular blood tests from ovulation to the onset of menstruation to establish how many pregnancies were ending in miscarriage before menses was even missed. The figure was zero.

    The second assumption is that the Rhythm Method fails when acts of intercourse close to either end of the “prescribed abstinence period” result in a pregnancy. Therefore, being at the limits of the window of fertility, these conceptions must be less viable and hence more likely to die. Bovens here demonstrates an appalling lack of knowledge of reproductive physiology. But more of that in a moment.

    His third assumption, which he says himself “is not backed by empirical evidence”, is that these conceptions, resulting from an “old” ovum or an “old” sperm, are then trying to “implant in a uterine wall that is not at its peak of receptivity”. This again denies the facts of the matter.

    Briefly – conception can only result from an act of intercourse which occurs when a woman’s body is receptive to sperm. This is for just a few days in each cycle when her cervix is open and is secreting mucus which can sustain sperm for more than the brief time that they otherwise live after ejaculation. This action of the cervix is triggered by rising oestrogen levels produced by the developing follicle in the ovary where the ovum is maturing.

    The combined fertility of the couple culminates with the rupture of the follicle and the release of the mature ovum at ovulation. The ovum, once released, lives for a maximum of 24 hours. It is only during this time that it is available to be fertilised. If conception does not occur the ovum dies and disintegrates, and the cervix becomes impenetrable to sperm.

    One function of the cervical mucus is to screen out defective sperm, or those that are “too old”, so that they never reach the waiting ovum. For verification of these scientific facts, see the published findings of Professor James Brown of Australia (hormones) and Professor Erik Odeblad of Sweden (cervical function).

    Once conception occurs, the zygote travels down the fallopian tube to arrive in the uterus approximately 6 days later. Implantation begins, and is completed by 12 days after conception. The endometrium (lining of the uterus), which was built up in response to the rising oestrogen levels (the proliferative phase of the endometrium) is then made ready for implantation by progesterone, which is secreted by the corpus luteum (the remains of the follicle) during the luteal phase of the cycle (the secretory phase of the endometrium). The zygote arrives in the uterus at just the right time for implantation, regardless of when the act of intercourse occurred which caused the conception, or even when in the woman’s cycle the ovulation occurred.

    Thus, Bovens’ detours via these three assumptions are all found to be dead ends. One lane of his dual-lane carriageway is found to be impassable – his “science” is flawed. The other lane – philosophy – goes by way of direct action (presumably as opposed to indirect action) and what he terms action/omission doctrine, though he says “this is not the place to turn to this discussion”.

    Sounds to me as though the carriage has ground to a halt – maybe the horse has run out of oats. And we must be travelling by horse and carriage, because the really glaring flaw in his argument, is that no-body now seriously advocates the Rhythm Method, nor has done for at least forty years. It was in the early 1950s that research began into a scientifically-based, clinical-proven alternative. The Billings Ovulation Method of natural fertility regulation, has a success rate, for avoiding pregnancy, equal to any chemical or surgical method, and a success rate for achieving pregnancy which is substantially better than any interventionist technique currently available.

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  3. We all have a finite lifespan

    Dear Editor,

    For simplicity, I will assume (as I actually believe) that all human embryos are persons, since Bovens is trying to argue that granting this assumption, the use of rhythm or Natural Family Planning (NFP) is if anything more morally problematic than the use of hormonal contraception, at least in respect of embryonic death. Let me grant Bovens' empirical assumptions, though they do not seem based on sufficient empirical data.

    Now, there is nothing morally problematic about conceiving someone who will die. Otherwise, every case of human conception would be morally problematic simply because human beings are mortal. When a conscientious couple deliberately conceives a child, they presumably believe that it is better to conceive a child who will live and die than not to conceive a child at all. Clearly nobody has been wronged.

    At the same time, it would be deeply morally problematic to conceive a child and to perform an additional act, before or after the conception, that causes the conceived human being's death. Consider a couple who to conceive a child and deliberately inject the embryo or ovum with a time-delay toxin that would cause the child to die at some specified future point. It does not matter whether the specified future point is in fourteen days, fourteen years, forty years or eighty years. The couple is directly responsible for the death of the human being, and as long as the death occurred at a time at which the law accounted the child a person, the couple would presumably be legally responsible at least for manslaughter. Someone is also clearly wronged here: Were the couple not to have injected the toxin, their child at least might have lived longer.

    Likewise in a case where use of hormonal contraception has made the uterus inhospitable to implantation, the use of the hormonal contraception is an act additional to conception by which the woman has brought it about that the child would be unable to survive more than about two weeks. Thus, the woman is directly responsible for the inhospitable conditions that would render implantation impossible or less likely.

    Moreover, it seems at least possible that someone is wronged by this act. It seems possible that the child who was conceived at time A might have been conceived at time A even had the contraception not been used, but would then have been better able to implant.

    Now in a case where uncontracepted sexual intercourse at a given time leads to a failure of implantation, a single act--intercourse--causes a human being to exist and to exist under conditions that make it impossible for the human being to survive more than about two weeks. But there is only one action here, and a fairly direct result of this action is conception. It is simply that the conceived child is, we assume, certain to die within about two weeks. The couple is not directly responsible for the death, since the couple did not create the conditions inhospitable to implantation.

    Furthermore, nobody is wronged by this act. For the child conceived at this point in time, call the time A, would not have come into existence had the couple abstained from the intercourse. Of course, if the couple engaged in intercourse at a different time, call it B, then perhaps the child conceived then would have lived longer. But that would have been a different child. By having intercourse at time A rather than at B, the couple is not wronging the child they are conceiving, since that child is not worse off for being conceived and living for two weeks than for not being conceived at all. Nor are they wronging the child they would have conceived at time B, since one cannot wrong someone who never exists. Moreover, there is no action the couple could have done to give the child who actually comes to exist a chance to live a longer life. No one has been wronged.

    A crucial assumption in my argument is that it is not worse to live for two weeks and die than not to live at all. A lot of pro-life people think that a human life, no matter its quality or length, is better than no life at all, and Bovens' argument was addressed to pro-life readers. But I can argue for my assumption even without regard for this controversial (though I think correct) pro-life position. For there are several things that are bad about the typical death of an adult human being. A typical list might be: (a) The human being is deprived of a future like ours, (b) various communities, friends and family are deprived of this human being's life, (c) the human being's plans and desires are interrupted, (d) the human being suffers pain in dying (spiritual, emotional and/or physical) and (e) friends, family and others suffer.

    Now, when the human being who dies is an embryo, the bads are like (a) and (b), as well as like (e), but not like (c) and (d), since the embryo does not seem to have plans, desires or pains. The bads in (a) and (b) are indeed serious. However, they are not bads relevant to the question whether it would be better to live for only two weeks or not to have lived at all. For (a) and (b) are deprivations of goods. And the goods in question, namely a future like ours and connection with various social networks, are lacking on both the scenario where the child lives for only two weeks after fertilization and on the scenario where no conception occurs. Thus the only relevant badness in the NFP scenario is that in (e). But that is suffering that at most happens to the couple, and an informed and competent individual is the best judge whether an instance of her suffering is worthwhile or not. Moreover, in practice, the couple does not know about the death of the embryo, and so the death does not cause specific pain, though knowing that deaths might occur could cause a moderate amount of psychological pain over time.

    Thus, there is nothing wrong with conceiving someone who will live for only two weeks after fertilization, as long as one had no way of conceiving her in such a way that she would have lived longer.

    The pro-life objection to hormonal contraception is not to embryonic death per se, but to the causing of conditions inhospitable to embryos, embryos that quite possibly (very difficult questions about identity are relevant here) could have lived longer were it not for these conditions.

    I am very grateful to Professor Bovens for a number of enlightening discussions.

    Sincerely yours,

    Alexander Pruss

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  4. Rhythm method as cause of embryonic death based on flawed assumptions

    Dear Editor,

    Luc Bovens’s assumption that intercourse on the fringes of the fertile phase of the menstrual cycle by users of rhythm will result in increased embryo loss is not based on convincing evidence (J Med Ethics, 2006;32:355-356). In fact, some scientific evidence points to the opposite conclusion. Researchers at the US National Institutes of Health Science reported they found no evidence for this association based on single acts of intercourse during the fertile window.(1) In a subsequent study they did find a significant increase in pregnancy loss from acts of intercourse on the estimated day of ovulation, but the study had severe limitations due to imprecise timing of intercourse and in estimating what acts of intercourse actually caused the pregnancy.(2) But neither of these studies involved couples using rhythm or what is commonly known as natural family planning (NFP).

    Researchers from Johns Hopkins and Georgetown University conducted a prospective study that included 373 unplanned and 367 planned pregnancies which occurred from women who were taught natural family planning (NFP) at 5 centers worldwide. The researchers found no significant differences in adverse pregnancy outcomes including spontaneous abortion rates between the two groups of women.(3) Although these same researchers found some evidence of poor pregnancy outcomes from unintended pregnancy compared to NFP couples who intended pregnancy, the poor pregnancy outcomes were only from couples who had a history of early pregnancy loss.(4) The largest study to test the hypothesis that users of NFP with unintended pregnancies have different pregnancy outcomes than couples that practice spontaneous intercourse resulted in no difference in pregnancy outcomes.(5)

    Bovens’s assertion about ageing gametes with use of rhythm and resulting spontaneous embryo wastage is not new. In fact moral theologians postulated this possibility in the 1970s.(6) Back then, their assertions were based on poorly designed research studies and circumstantial evidence. One of the studies was a thesis that involved a retrospective assessment of parents of mentally handicapped children from one Dutch village who were asked, up to 10 years later, to recall when the conception intercourse occurred. These couples practiced a calendar-based system of NFP, not the more modern methods that rely on biological markers of fertility. The same researcher also provided circumstantial evidence of an increase of Downs Syndrome by young Catholic mothers using NFP.(7) Guerrero and Rojas tested the ageing gamete theory and seemed to show an increase in the spontaneous abortion rate and possibly malformations based on the recordings of the basal body temperature thermal shift and timing of artificial insemination.(8) However, we now know that the thermal shift is a very imprecise method of estimating the fertile phase, and conclusions based on this biological marker are fraught with error. Poor scientific studies result in poor outcomes and false conclusions.

    Physiological mechanisms in the human being facilitate fresh gametes for the process of fertilization. During the fertile phase of the cycle, estrogen stimulated cervical mucus serves the purpose of filtering out defective sperm. Only the most robust succeed in reaching the ovum. Furthermore, the ovum is viable only about 12 – 24 hours. Approximately 50 -75% of spontaneous abortions are a result of chromosomal abnormalities of the embryo, and most of these occur by chance.(9) How much of this chromosomal damage is due to ageing gametes from intercourses on the fringes of the fertile phase has not been documented. Other factors contributing to early embryonic loss include uterine abnormalities, immunologic disorders, bleeding disorders, endocrine disorders, infections, and environmental factors such as smoking. The more troublesome ageing factor is oocytes from older women, especially when they have intercourse with older men. Women in modern developed countries tend to delay (largely by use of hormonal contraception) having children until later in life, often at an age when their fertility is in decline and their oocytes are diminished and genetically old.(9,10)

    In fact, it could be postulated that couples using hormonal contraception will contribute to higher spontaneous abortion rates and poorer pregnancy outcomes than couples using other forms of family planning. Many couples who are on hormonal contraception will eventually discontinue the contraceptive pill to achieve a pregnancy. (Please note that couples do not stop using NFP when they want to achieve a pregnancy – in fact, NFP helps couples to target the fertile phase). Couples who discontinue hormonal contraception often experience irregular menstrual cycles, delayed ovulation, longer follicular phases, and shortened luteal phases.(11) Longer follicular phases and shortened luteal phases have been cited as factors that could contribute to oocyte ageing and early spontaneous embryo loss.(12) Millions of women discontinue hormonal contraception each year to achieve a pregnancy. Should we ask them to avoid achieving a pregnancy until their cycles normalize?

    The highest probabilities of pregnancy from an act of intercourse during the fertile window are the two days before the day of ovulation.(13) We do know that there are factors that decrease this probability such as poor quality cervical mucus, the age of the woman and the man (not the age of the gametes), and smoking.(14,15) If you accept absolute numbers of natural preimplantation losses of 50%, then it is likely that these will occur much more (in absolute terms) with intercourse during the days of highest fertility. That is, if 50% of all zygotes fail to implant, since there are many more zygotes formed at days of peak fertility, there will be many more failed implantations during the high fertile time. This is true even if the percentage of failed implantations on the extreme margins of the fertile period were to be slightly higher (say 1% or 5% more) - a possibility that we can't entirely exclude.

    From an ethical standpoint, even if you hold to the assertion that fertilization on the margins of the fertile time results in embryos loss, that doesn’t mean NFP use is causing embryo deaths in any morally relevant sense. Thisis the case for at least two reasons, first, intercourse at these times is not unique to NFP users. Where is the evidence that NFP users have intercourse on the edges of the fertile phase significantly more than the general population? Research has indicated couples have intercourse more frequentl on the weekend when there is more time and less stress.(16) Weekend intercourse will result in intercourse anytime during the fertile phase, including the fringes. Second, having intercourse at these times does not equal doing anything (either “action” or "omission") to the woman or the embryo to cause the embryo’s death – as is the case when a woman uses an abortifacient drug or device. The parallel Bovens tries to draw between the two cases just doesn’t work. The point is basically the same as one would make in distinguishing between [non- abortifacient methods of] contraception and NFP. They both avoid fertilization, but contraception does so by doing something to the act of intercourse – either an "action" or [in the case of withdrawal] an "omission" – that takes away as much as possible of the fertility it would otherwise have. NFP does nothing of the sort.

    NFP helps couples to monitor, understand, and live with their fertility. Contraception works to block, suppress, or destroy fertility -- actions that are contra fertility and, at times contra life. Fertility for many couples is a precious and awesome gift. Human life is precious and at the most vulnerable during the passage from the fallopian tubes to the womb. The assumption that intercourse on the edges of the fertile phase leads to the utilization of aged gametes and increased embryonic destruction is plausible, but there is scant evidence of this among human beings. The assumption that practicing NFP results in the use of aged gametes and increased embryonic death has no good evidence and in fact some good evidence to the contrary. The use of NFP is not an action or omission against embryonic human life anymore than normal human living and loving. Taking Bovens’s notion to the extreme would mean that couples should not have intercourse at all – since, it might result in a spontaneous abortion. Perhaps the real absurdity is the thinking that what is natural is bad and what is destructive of fertility is good.

    Separating sexuality from fertility is a dualistic system counter to the natural intent of the sexual act. It only works in a fantasy world with a false sense of sexual freedom by use of condoms, hormonal contraception, emergency contraception, abortion as a backup, IVF when a perfect child is wanted, and sterilization when fertility is no longer desired. This dualism creates a false representation of human being, human relations, human boding, and the transmission of human life.


    1. Wilcox AJ, Weinberg CR, Baird DD. Timing of sexual intercourse in relation to ovulation, effects on the probability of conception, survival of the pregnancy, and sex of the baby. N Engl J Med, 1995;333:1517-1521.

    2. Wilcox AJ, Weinberg CR, Baird DD. Post-ovulatory aging of the human oocyte and loss of pregnancy. Hum Reprod, 1998;13:394-397.

    3. Bitto A, Gray RH, Simpson JL, Queenan JT, Kambic RT, Perez A, Mena P, Barbato M, Li C, Jennings V. Adverse outcomes of planned and unplanned pregnancies among users of natural family planning: a prospective study. Am J Public Health, 1997 Mar;87(3):338-43.

    4. Gray RH, Simpson JL, Kambic RT, Queenan JT, Mena P, Perez A, Barbato M. Timing of conception and the risk of spontaneous abortion among pregnancies occurring during the use of natural family planning. Am J Obstet Gynecol, 1995 May;172(5):1567-72.

    5. Barbato M, Bitto A, Gray RH, Simpson JL, Queenan JT, Kambic RT, Perez A, Mena P, Pardo F, Stevenson W, Tagliabue G, Jennings V, Li C. Effects of timing of conception on birth weight and preterm delivery of natural family planning users. Adv Contracept, 1997;13:215-28.

    6. Haring B. New dimension of responsible parenthood. Theological Studies, 1976:37:120-132.

    7. Jongbloet PH. The ageing gamete in relation to birth control failures and Down syndrome. Eur J Pediatr, 1985 Nov;144(4):343-7.

    8. Guerrero R, Rojas OI. Spontaneous abortion and aging of human ova and spermatozoa. N Engl J Med, 1975;293:573-575.

    9. Speroff L, Fritz MA. Recurrent early pregnancy loss. Chapter in Clinical Gynecology Endocrinology and Infertility. Phildelphia: Lippincott Williams & Wilkins, 2005:1069-1101.

    10. ESHRE Capri Workshop Group. Fertilty and ageing. Human Reprod Update, 2005;11:261-267

    11. Gnoth C, Frank-Hermann P, Schmoll A et al. Cycle characteristics after discontinuation of oral contraceptives. Gynecological Endocrinology, 2002;16:307-317.

    12. Tarin JJ, Pérez-Albala S, Cano A. Consequences on offspring of abnormal function in ageing gametes. Hum Reprod Updates, 2000;6:532-549.

    13. Wilcox AJ, Dunson D, Baird DD. The timing of the "fertile window" in the menstrual cycle: day specific estimates from a prospective study. BMJ, 2000 Nov 18;321(7271):1259-62.

    14. Dunson DB, Colombo B, Baird DD. Changes with age in the level and duration of fertility in the menstrual cycle. Hum Reprod, 2002 May;17(5):1399-403.

    15. Scarpa B, Dunson DB, Colombo B. Cervical mucus secretions on the day of intercourse: an accurate marker of highly fertile days. Eur J Obstet Gynecol Reprod Biol, 2006 Mar 1;125(1):72-8.

    16. Wilcox AJ, Barid DD, Dunson DB, McConnaughey DR, Desner JS, Weinberg DR. On the frequency of intercourse around ovulation: evidence for biological influences. Hum Reprod, 2004;19:1539-1543.

    Acknowledgements: I wish to thank Joseph Sanford, MD and Professor Kevin Miller for ideas included in my response.

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  5. Re: A reply to my critics

    Dear Editor,

    A response to Bovens' reply to his critics.

    Readers generally would have thought the original article to be about early embryo loss and NFP. The Response of 12th June seem to have moved on somewhat from this.

    Rather than keeping to early embryo loss, Bovens now provides figures giving overall observed and estimated embryo losses; and not so much in observational studies of healthy natural human conception, but in IVF studies, human studies giving sub-groups with medical problems, animal AI studies, and human and animal studies where ovulation or fertilisation were manipulated to varying extents, and from which there is 'extrapolation' and 'guess'. In healthy human populations conceiving naturally, the decreased survival rates related to delayed implantation rather than "ageing" gametes. Atypical cycles – a very vague term – deserve investigation rather than quotation as the norm, and cycle variations provide no problem to modern NFP. The opening section shoehorns modern NFP in with a calculation-based approach that no-one has advocated for 40 years, and later on Bovens equates or identifies NFP with contraception in any form.

    Whatever the disagreements about percentages and extrapolations, the ethics of natural conception cannot be decided on their basis. In his later paragraphs on ethics, Bovens seems effectively to equate early or late foetal loss with induced abortion. This is compounded by his suggesting that foetal loss be regarded as a side effect of intercourse, if this is in any way "targeted". "Fanciful thought experimentation" follows, in which particular conditions are imposed on any double-effect consideration. Conjecture is of use if it leads to clarification; but the only end result here is a construct whose practical meaning is to try to strip natural human conceiving, if in any way informed, of any innocence or presumption of good.

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  6. Are these results of a study or suggestions only?

    Comments to the paper of L Bovens “The rhythm method and embryonic death“, J. Med. Ethics 2006; 32:355-356

    Dear Editor,

    There is no evidence that a conceptus has reduced survival chances if conception occurred on the fringes of the fertile period looking into data concerning the first 6 weeks of pregnancy (see also (Raith, E, Frank, P. et al. 1999; Freundl, G, Gnoth, C. et al. 2001; Frank, P., Freundl, G. et al. 1985). Also no association was found between aged spermatozoa and early pregnancy loss (Wilcox, A. J., Weinberg, C. R. et al. 1998). In the late 1980s, the issue of aging gametes and pregnancy outcomes was thoroughly investigated, although the author does not seem to be aware of this literature (Simpson, J. L., Gray, R. H. et al. 1988;Simpson, J. L., Gray, R. H. et al. 1997). Bovens fails to make the necessary moral distinction between natural loss of an embryo and loss caused by deliberate human intervention. Natural Family Planning does not cause loss of the embryo, and is not intended to do so. On the other hand, the oral contraceptive pill, the morning-after pill, Norplant, and the IUD all may cause abortions because one of their mechanisms of action is to impede implantation of the embryo in the uterine endometrium. Alcom (in the reference listed cited as Alcorn!!), who was cited in the paper (Alcom, R 2005;Alcom, R and Larimore, WL 2006), stated that regardless of the likelihood of implantation failure under such circumstances, any such failure is spontaneous, not induced, and thus, for Alcorn, is a miscarriage, which he does not consider ethically problematic.

    It is only at the very end of his paper that Bovens admits to the possibility that his probabilistic arguments about the likelihood of implantation failure can potentially be addressed by making the distinction between artificially inducing an environment "in utero" inhospitable to implantation vs. its natural occurrence as part of the ovulatory cycle. But he fails to admit that Alcom makes this distinction all along.

    Boven’s first assumption that 50% of natural human conceptions are lost is an often-repeated figure based on problematic research in 1956 using histological analysis of hysterectomies where intercourse was encouraged prior to surgery. The higher figure of 78% often quoted rests on a 1975 analysis of a hypothesis based on a series of weak assumptions.

    In summary, we think that concerning the Natural Ethics of Harris (see references in the article) the article fails to acknowledge the distinction between natural loss and loss caused by deliberate human intervention; common sense and every criminal law system recognises the importance of knowledge and intent in human responsibility. In particular, the fact that accidental deaths happen does not justify causing similar deaths. Bovens adopts Harris’ perspective, that the knowledge that some embryos will not naturally survive, amounts to convicting any couple then continuing to conceive naturally of “destruction” of embryos. Philosophically however it is even more problematic to think that people cannot have a say by controlling their reproductive life. Technically we can spend our whole life in bed trying to have babies, since every moment that passes is an opportunity 'lost'. Indeed this in itself is a reductio ad absurdum of Boven's argument.

    Finally, I am concerned as such an article in a well known ethical journal obviously influences various publications (Catholic News Service, 6/2006 and catholic news, 7 Jun 2006) to statements as such “…using natural family planning to have only one or a maximum of two children is nothing other than a kind of series of brief parentheses within an entire conjugal life willingly made sterile". Bovens did not write it directly, but his article paves the way for rejecting NFP as a method of family planning for religious people as well. Is that what we want?

    Reference List

    1. Alcom,R. (2005) Does the birth control pill cause abortions? Gresham, OR: Eternal Perspective Ministries, 50-73.

    2. Alcom,R. and Larimore,W. (2006) Does the birth controll pill cause abortions? The growing debate about the abortifacient effect of the birth controll pill and the principle of the double effect. Ethics in Medicine, in review.

    3. Frank,P., Freundl,G., and Gray,R.H. (1985) [Natural family planning. Introduction and epidemiologic studies] Gynakologe., 18, 224- 230.

    4. Freundl,G., Gnoth,C., and Frank-Herrmann P. (2001) Freundl,G. (ed), Kinderwunsch - Neue Wege zum Wunschkind. Gräfe und Unzer, München, 1 -289.

    5. Raith,E., Frank,P., and Freundl,G. (1999) Raith-Paula,E., Frank- Herrmann P., and Freundl,G. (eds), Natürliche Familineplanung heute mit ausführlicher Darstellung der Zykluscomputer. Springer, Berlin, 1-273.

    6. Simpson,J.L., Gray,R.H., Perez,A. et al (1997) Pregnancy outcome in natural family planning users: cohort and case-control studies evaluating safety. Adv.Contracept., 13, 201-214.

    7. Simpson,J.L., Gray,R.H., Queenan,J.T. et al (1988) Pregnancy outcome associated with natural family planning (NFP): scientific basis and experimental design for an international cohort study. Adv.Contracept., 4, 247-264.

    8. Wilcox,A.J., Weinberg,C.R., and Baird,D.D. (1998) Post-ovulatory ageing of the human oocyte and embryo failure. Hum.Reprod., 13, 394-397.

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  7. A reply to my critics

    Dear Editor,

    Some of my critics draw a distinction between the rhythm method and natural family planning (NFP). I take the rhythm method to be any method that relies on abstinence around the time of ovulation. Of course there are various ways to determine when ovulation occurs, including the calendar method (Ogino Knauss), examining mucus (Billings) or checking basal temperature (STM). I do not take this method to cover the use of barrier methods during the fertile period, as some definitions of both ‘NFP’ and ‘the rhythm method’ seem to permit. I find reports on success rates for this method between 75% as the lowest number for typical use and 99.3% as the highest number for perfect use. Should one use numbers for perfect use or for typical use in moral arguments? On the one hand, one could say that a proponent of a method of contraception should not have to take responsibility for people failing to follow proper instructions. But on the other hand, recommendations are for real people and real people are not perfect users. To postulate a 90% success rate does not seem to be out of line with the available evidence. It is probably somewhat too low for perfect use and somewhat too high for typical use.

    If the method fails, then how does it fail? If the purpose is to avoid having sex around the time of ovulation, then the following seem to be reasonable answers. (1) The last time of having sex before the period of abstinence was too close to ovulation. (2) The first time of having sex after the period of abstinence was too close to ovulation. (3) Ovulation was atypically early or late during some cycle and though the users checked the markers for ovulation, they failed to determine its occurrence accurately. Or a combination of (1) and (3) or of (1) and (2) are also reasonable. Since we are talking about typical use, such failures could be due to self-deception and wishful thinking. (1) raises the problem of ageing sperm, (2) raises the problem of an ageing ovum and (3) raises the problem of an atypical cycle.

    Now comes the main empirical point of contention. For my argument to work, it must be the case that the probability of viability given that a conception occurs with ageing sperm or ovum or during an atypical cycle is lower than the probability of viability given that a conception occurs with fresh sperm and a fresh ovum and during a typical cycle. Both Mark Witty and Anne Williams phrase the objection to this assumption very well. "There is no evidence that there is any variability of viability of the conceptus with time of fertilisation within this narrow window," writes Williams. “Any conception is as viable as the next, barring a fatal genetic or developmental defect; there is no truth to the 'old sperm' or 'old ovum' speculation...," writes Witty. So let us turn to the relevant empirical literature.

    Tarin et al. (2000) review a fifty-year literature not only on the effect of ageing gametes on pre-menstruation embryonic loss, but also on fertilization, spontaneous abortions and the pathology of the offspring. A range of studies is reviewed of in vivo and in vitro fertilizations with ageing gametes, involving humans, non-human mammalians, and non-mammalians. These studies are not always univocal. Furthermore, we often have to extrapolate from non-human animal populations, in vitro contexts, and patients with a history of infertility to what might be happening in human populations of normal fertility in in vivo contexts. Sometimes the best we can do is to guess what would provide the best explanation for experimental results. Nonetheless, I do think that there is a trend present which supports the idea that viability given conception may vary with the age of the ovum, the age of the sperm and whether the cycle is or is not typical.

    As to ageing ova, I quote: "It appears that ... post-ovulatory ageing of oocytes is associated with: (i) decreased potential of oocytes for fertilization and pre- and / or post-implantation embryo/fetus development." (Tarin et al., 2000: 544) Table 1 (Tarin et al., 2000: 533) contains a range of studies documenting the effect of the ageing of the ovum on embryo/fetus development and mortality. To pick one example, Wilcox et al. (1998) study ovulation, hCG levels and intercourse patterns of a cohort of women attempting pregnancy and find an increase in post- implantation embryonic loss for intercourse on the day of ovulation in human populations. Considering the time-lag between intercourse and fertilisation, these data support the hypothesis that post-ovulatory ageing of ova compromises embryonic survival. (I should add that Wilcox et al. (1998) do not record any conceptions from intercourse after the day of ovulation.) Wilcox et al. (1999) compare late implantations and early implantations. Late implantations have levels of embryonic loss that are radically higher (82% after day 11) than early implantations (13% up to day 9) . However, it is not known what causes these late implantations.

    As to old spermatozoa, I quote from Tarin et al., 2000: 544: "Likewise the ageing of spermatozoa in ... the female reproductive tract ... is associated with decreased ... potential for fertilization and pre- and/or post-implantation embryo/fetus development." Table 2 contains entries with articles documenting the effect of in vivo ageing of spermatozoa in the female genital tract and increased embryo/fetal mortality with ageing spermatozoa. Tarin et al. (2000: 542) write: "This notion is supported by the high mortality rate observed in embryos/fetuses derived from sperm aged in stagnant environments, e.g in ... the] female reproductive tract." Parkening and Soderwall, in a study of golden hamsters, write that their data "indicate that inseminated spermatozoa are capable of penetrating the zona pellucida and fertilizing some ova after residing 14 to 16 h within the female reproductive tract, but that the viability of ova fertilized in this manner is greatly reduced." (1975: 627-8) There are supporting results about golden hamsters in Bell and Shaver (1982). Vishwanath and Shannon find that after storage, bull sperm may retain its "oocyte penetrating ability", yet "mitochondrial DNA damage and chromosomal abnormalities" could "compromise the viability of the resulting conceptus." (1997: 321-32)

    One might conjecture that if there is a higher rate of early embryonic loss in conceptions involving ageing gametes, then there would also be a higher rate of spontaneous abortions. Gray et al. (1995: 1568) cite a number of studies that confirm this finding. However, in his own study, he does not find a difference in the spontaneous abortion rate for conceptions resulting from intercourse on the day before or on the day of ovulation on the one hand and from intercourse outside this narrow window on the other hand within the total population. There is however a significant difference in the spontaneous abortion rate in the subpopulation of women who have had spontaneous abortions before. There is no conclusive interpretation of these results.

    Let us now turn to atypical cycles. There are many open questions here and much of my evidence comes from consulting with researchers in the field. Implantation rates are dependent on the nature of the embryo and the development of the endometrium. In IVF (in vitro fertilisation), ovulation is timed carefully by adjusting drug dosages so that it comes neither too early nor too late. This might indicate that the quality of the ovum could be a function of ovulation time and since we can control for fertilisation in IVF, the concern is a concern about the viability of the embryo. In IUI (in utero insemination), some doctors will refrain from inseminating in case of an early ovulation. This might indicate that the quality of the ovum is compromised when there is early ovulation or that a short follicular phase may compromise the development of the endometrium. Early ovulation is believed to correlate with higher rates of oocyte aneuploidy leading to more pre- and post-implantation embryonic loss due to chromosal abnormalities. About late ovulations, Tarin et al. (2000: 535) write that "...under particular circumstances, including long follicular phases ... fully grown GV oocytes may undergo pre-ovulatory ageing before the occurrence of the endogenous LH surge ..." (2000: 535) He also presents a list of studies documenting the effect of pre-ovulatory ageing on fertilization, the development of the embryo and the offspring. (2000: 534)

    Whitty objects to my use of the figure of 50% of embryonic loss, claims that such high figures are based on old and questionable studies (from 1956 and 1975), and that animal studies give single-digit percentages. A standard source for embryonic mortality is Edmonds (1982). Edmonds assesses embryonic loss by the appearance and disappearance of hCG in the urine at the time of implantation and presents a figure of 62%. This underestimates the actual percentage since it does not count pre-implantation loss. In Wilcox et al.'s study (1999) the pre-menstruation embryonic loss plus miscarriages is at 33%. Why is there this discrepancy? The only explanation that I can see is that Edmonds samples from a normal population, whereas Wilcox restricts his population to couples without previous fertility problems. In any case, considering that this does not measure pre-implantation loss, a figure of 50% for normal populations does not seem outlandish in the face of these data.

    So far I have tried to defend the assumptions that come into the model. But of course, it is another thing to check whether the predictions of the model hold true in the real world. Clearly we know too little to fill in the values of all the parameters. It may be the case that, say, the viability given conception is variable, but this variability is not sufficiently great to obtain meaningful differences between embryonic death rates for condom users and NFP users. Or there can be hidden variables that are not included in the model. In principle, it is possible to do the following empirical test. One could compare post -implantation embryonic loss rates between condom users and NFP users by checking for hCG in urine tests. However, in practice, this would require quite a large number of subjects, because in any given cycle, there would only be a relatively small number of conceptions. This would be one step forward, but it would still not yield information about pre-implantation embryonic loss, because hCG does not register in the woman’s blood or urine before implantation.

    Let us turn to the philosophical objections. My critics claim that even if I were right about the empirical data, there would still be a moral divide between NFP and contraceptive pills, because the embryonic deaths occurring on NFP would be "natural deaths" whereas the deaths occurring on contraceptive pills would be "induced deaths", in Ira Winter’s words. Justin and Sue Fryer talk about "letting nature take its way" versus "deliberately taking action by swallowing a pill, or other means, to end the life of an embryo". And Mark Whitty points to the relevance of the doctrine of double effect.

    These are difficult issues that require a much more careful analysis than what I can offer at this point. Let us clearly bracket the empirical issues from the philosophical issues. My critics say that even if I were right about the empirical details, then we could still invoke the action/omission doctrine or the doctrine of double effect to draw a distinction between NFP and contraceptive pills. So let us not quibble about empirical data from here on and suppose—to make things simple—that a particular implementation of NFP and a particular contraceptive pill, would lead to the same number n of conceptions, lead to the same number of embryonic deaths d, and lead to the same number of live births m. And let us suppose that condoms lead to the same number m of live births but with fewer conceptions and hence fewer embryonic deaths. A final alternative is abstinence with carefully targeted pregnancies, leading to m life births with even fewer conceptions and even fewer embryonic deaths.

    Let us do the following admittedly fanciful thought experiment. Suppose that conceptions always lead to live births. However, all these contraceptive techniques would have the same mechanisms and consequences as they now have, substituting neonatal death for embryonic death. So a contraceptive pill user would have n conceptions, n live births, but d deaths of newborns and hence only m children that survive for longer than, say, one week. Similarly for NFP, condom usage and abstinence with targeted pregnancies. Would there not be an outcry about any method that would have an excessive neonatal death rate? Could we defend NFP on grounds that the deaths of these newborns is just nature’s way or on grounds that these deaths are not intended? I don’t think so. If embryos have the same moral status as newborns, then why would we think that we can put up such defences for NFP involving embryonic death?

    Now I am a friend of the action/omission doctrine and the doctrine of double effect. For example, as to the action/omission doctrine, I do agree that one has to have better reasons—i.e. the prognosis has to be worse—before one is justified to withdraw treatment (action) rather than withhold treatment (omission). As to the doctrine of double effect, suppose that I can advance the war effort to the same extent by target bombing, say, by bombing a depot, while expecting to kill n innocent civilians living around the depot as collateral damage, as by terror bombing, say, by bombing a neighbourhood with the intention of killing n innocent civilians. I do agree that terror bombing is worse than target bombing. But just to say that bad effects did not come about due to direct agency or were not intended is not sufficient to make a practice permissible on the action/omission doctrine or on the doctrine of double effect. The bad effects also have to be outweighed by the good effects and furthermore, there must be no other practice (in which the bad effects do not come about due to direct agency or were not intended) that achieves the same good effects while incurring fewer bad effects.

    Further to the action/omission doctrine: There is a continuum between agency (say, a direct killing of an embryo) and an omission (say, not providing a drug that would prevent a miscarriage). Now one might argue that, on this continuum, "taking a pill so that fertilisation is unlikely to occur or so that the endometrium is inhospitable for incoming embryos" is more on the action side than "organizing your sex life so that fertilisation is unlikely to occur or so that embryos are either non-viable or come in at times when the endometrium is not hospitable". But is the distance on this continuum sufficiently great to make the former qualify as a grave sin and the latter as a morally permissible method of birth control? I am not convinced. Maybe it is worse to remove edible plants and animals from an island to make it inhospitable and then to drop off someone on it than to carefully pick a time of the year to drop off someone when you know the island not to be hospitable for human habitation. But really, is it that much worse? And furthermore, even if, given our assumptions about the numbers, contraceptive pills are worse than NFP on action/omission grounds, then would one not want to reverse this judgment if embryonic death rates for NFP would come to exceed embryonic death rates for contraceptive pills to a sufficient degree?

    Clearly we carry some responsibility for the consequences of our omissions. If embryonic deaths are a bad thing, then should we not try to minimize them? Indeed, we should take due care, also in our omissions. And, given my assumptions, there are alternatives available, viz. condoms and abstinence with targeted conceptions, that come at a lower embryonic death rate.

    I have two concerns with invoking the doctrine of double effect. Clearly it is not enough to say that an NFP user does not intend the embryonic death. This would get a pill user off the hook. She could just say that she only intends to block ovulation by taking this pill and furthermore she intends this as a means not to become pregnant. A proponent of the doctrine of double effect would just say to the pill user that if embryonic death were not to occur she would shoot short of her target – there would simply be more pregnancies. Embryonic death is integral to reaching her goal while, say, the deaths of innocent civilians in target bombing are not. But the same response holds for the NFP users. Without the embryonic deaths, there would be more pregnancies.

    Secondly, target bombing would be no longer permissible if there were another way to gain the same military advantages at a lower cost in the lives of innocent civilians. But is this not what we are facing in the case of NFP? There are alternative ways to gain the same advantages at a lower cost of embryonic deaths, e.g. by condom use. Now I realize that there may be independent grounds for opposing condom use as a malum in se, but then there is the possibility of abstinence with targeted conceptions. Granted, the gains of sex are lost in abstinence, but do they weigh up against embryonic deaths?

    Clearly there are many open questions in this area. And I have not even touched on questions about the status of the embryo. These are not only questions in the context of the pro-life versus pro-choice debate. For instance, some critics have pointed out that many of my embryonic deaths are deaths of defective embryos and defective embryos are not possible persons. Other critics have claimed that embryonic deaths as such are not a bad thing, but that killing an embryo is nonetheless a wrong action. Many such questions remain unexplored.

    My intention here was to point out that an appeal to the action/omission doctrine or the doctrine of double effect does not straightforwardly block the argument. Maybe it can be blocked. To make headway on this issue will require some serious thinking and constructive dialogue.

    Let me take this occasion to thank my critics in JME, e-mail correspondents and bloggers for their thoughtful comments. I am also grateful for helpful (e-)conversations with Roger Gosden, Kathy Hoeger, Kathy King, Michael Otsuka, Alexander Pruss, Danny Schust, Alan Thornhill, and Alex Voorhoeve.


    Bell, C.L. and Shaver E.L. (1982) Analysis of preimplantation golden hamster conceptuses resulting from spermatozoa aged in utero. Gamete Res., 6: 199-207.

    Edmonds, D.K., Lindsay, K.S., Miller, J.F. Williamson, E. and Wood, P.J. (1982) Early embryonic mortality in women. Fertil. Steril., 38, 447- 53.

    Gray, R.H., Simpson, J.L., Kambic, R.T., Queenan, J.T., Mena, P., Perez, A. and Barbato, M. (1995) Timing of conception and the risk of spontaneous abortions occurring during the use of natural family planning. Am. J. Obstet. Gynecol., 172, 1567-72.

    Parkening, T.A. and Soderwall, A.L. (1975) Delayed fertilization and preimplantation loss in senescent golden hamsters. Biol. Reprod., 12, 618- 31.

    Tarin, J.J., Perez-Albala, S. and Cano, A. (2000) Consequences on offspring of abnormal function in ageing gametes. Hum. Reprod. Update, 6, 532-49.

    Vishwanath, R. and Shannon, P. (1997) Do sperm cells age? A review of the physiological changes in sperm during storage at ambient temperature. Reproduction, Fertility and Development, 9, 321-32.

    Wilcox, A.J., Weinberg, C.R. and Baird, D.D. (1998) Post-ovulatory ageing of the human oocyte and embryo failure. Human. Reprod., 13, 394-7.

    Wilcox, A.J., Baird, D.D. and Weinberg C.R. (1999) Time of implantation of the conceptus and loss of pregnancy. N. Engl. J. Med., 340, 1796-99.

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  8. Alcorn misrepresented, argument misses mark

    Dear Editor,

    Bovens' argument is clever, but it misrepresents Alcorn, and pro-lifers in general, as being concerned about the absolute number of embryonic deaths without distinction as to the cause. But even a cursory reading of Alcorn (e.g. makes it clear that Alcorn's concern is not embryonic death in general, but induced embryonic death: Alcorn merely applies the customary ethical distinction between induced abortion and miscarriage to the situation of a fertilized embryo facing implantation.

    Alcorn argues that the use of forms of contraception that create an environment "in utero" inhospitable to implantation (IUD, pill) in so doing induces the death of the embryo (which cannot survive long without implantation), making it ethically comparable to induced abortion. In response, Bovens argues that implantation failures can also conceivably occur when periodic abstinence is being used to avoid pregnancy. However, the convoluted probabilistic arguments Bovens uses to estimate how likely implantation failure might occur, arguments that make up the bulk of the paper, are quite beside the point: regardless of the likelihood of implantation failure under such circumstances, any such failure is spontaneous, not induced, and thus, for Alcorn, is a miscarriage, which he does not consider ethically culpable.

    It is only at the very end of his paper that Bovens admits to the possibility that his probabilistic arguments about the likelihood of implantation failure can potentially be addressed by making the distinction between artificially inducing an environment "in utero" inhospitable to implantation, vs. its natural occurrence as part of the ovulatory cycle. But he fails to admit that Alcorn makes this distinction all along; Bovens merely states that he thinks the distinction asks "more from the action/omission doctrine than it can deliver", and leaves it at that. But if Bovens is serious about addressing Alcorn, it is here that his paper should start, not end.

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  9. Re: Rhythm method and embryonic death

    Dear Editor,

    I have two comments to make with regard to the article about the rhythm method. It is not true that the Catholic Church only approves the “rhythm” method of family planning. It approves all natural methods and especially the Billings Ovulation Method of natural fertility regulation that has a better than 99% effectiveness rate, as shown in numerous recent published studies. (

    On a philosophical level L. Bovens’ argument is flawed in trying to equate natural miscarriages with induced abortion of a healthy embryo. A ten year old child would be able to see the moral distinction between nature taking its course as in the case of a miscarriage and deliberately taking action by swallowing a pill, or other means, to end the life of an embryo.

    Justin and Sue Fryer

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  10. Comment on Bovens' article on embryo death

    Dear Editor,

    This article on Reproductive Ethics is unfortunate in a number of respects, and while I would not identify with the pro-life movement of the article, I feel it necessary to respond from the standpoint of a proponent of the modern Billings Ovulation Method of Natural Family Planning (NFP).

    NFP Methods
    Bovens seems to choose to reduce all NFP to one approach, the definitively obsolete Rhythm Method. This alone renders the basis of the article’s moral extrapolations to all NFP at best inappropriate, and signals that the “plausible empirical assumptions” on which much else in the article is based are inapplicable to current NFP use. Boven’s second assumption is correct only in the sense that the obsolete rhythm method was a statistical calculation, and intercourse on days adjacent to the required abstinence phase’s limits could in a minority of cases result in conception, because that method failed to recognise the natural variation of cycles, which almost all current NFP methods do. It is not correct, however, as a basis for what follows in the article.

    Boven’s first assumption that 50% of natural human conceptions are lost is an often-repeated figure based on problematic research in 1956 (1) using histological anaysis of hysterectomies where intercourse was encouraged prior to surgery. The higher figure of 78% often quoted rests on a 1975 analysis (2) of an hypothesis based on a series of weak assumptions. Animal studies commonly give percentages in single figures. Boven’s third assumption is wholly invalid in the light of current knowledge of human reproductive physiology. The ovum lasts for about 12 hours, 24 at most; sperm may last up to 3-5 days with the support of both the appropriate types of cervical mucus and of the activity of the cervical crypts. Any conception is as viable as the next, barring a fatal genetic or developmental defect; there is no truth to the old “old sperm” or “old ovum” speculation, or its “twice as likely to be viable”, “lack resilience” and “reduced survival chances” assumption. Neither is there any truth in the “heightened fertility (HF)” and ‘tail- end fertility” idea, with or without further speculative assumptions about extrapolated comparative embryonic viability based on this innacuracy. A luteal phase of less than 11 days may be insufficient to sustain a natural conception, but this is a case for medical intervention. So all that follows based on the HF and other assumptions is invalid. His fourth point of counter-argument depends on the idea that natural conception could be timed in NFP use for when the endometrium is inhospitable to an embryo; this is physiological nonsense. The symphony of ovulation-related events ensures that the endometrium is ready for implantation until when either the corpus lutem expires or ßHCG is produced. It is a complete fallacy to assert, even in regard to the obsolete rhythm method, that any NFP methods “depend for their successes on massive embryonic death”.

    Natural Ethics, Harris
    The article fails to acknowledge the distinction between natural loss and loss caused by deliberate human intervention; common sense and every criminal law system recognise the importance of knowledge and intent in human responsibility; in particular, the fact that accidental deaths happen does not justify causing similar deaths. Bovens adopts Harris’ perspective, that the knowledge that some embryos will not naturally survive, amounts to convicting any couple then continuing to conceive naturally of “destruction” (3) of embryos. This is a thesis open to redutio ad absurdum, and rests on Harris’ having dismissed to his satisfaction the double effect principle patently used universally in daily life and medical practice.

    Probability Calculus
    Any mathematical model’s results based on inaccuracies and guesses are misleading; the comparative scale of embyonic loss is baseless because the fundamental assumption in regard to NFP and embryo survival is unsupported by the evidence.

    The article’s use of Alcorn is open to question. He proposed an “infinitesmal” small proportion (0.01%) of pill-use cycles resulting in a conception lost due to pill use, to provide a minimum statistic for purposes of illustration and contrast. Bovens takes Alcorn’s minimal estimate and uses it as if it were fact in regard to embryo loss on the combined oral contraceptive pill, so that his supposed “loss” with use of the rhythm method seems huge by comparison. What is known is that older formulations of the pill allowed breakthrough ovulation in 2-10% , (4,5) or 4.7% (6) of cycles, and about 27 cycles per 100 women per year in later studies (7). Progesterone preparations have higher ovulation rates, and the IUD still higher. Recording or calculating a ‘conception and loss rate’ for these cycles is another matter.

    Condom use statistic
    Any manufacturer would be delighted to be able to claim a 95% use-effectiveness for his condom. 88% is more usually quoted as an average figure.

    “can this argument be blocked?”
    The first point is in fact valid; the article’s embyonic death proposition is untenable, being based on ignorance and error in physiology – sadly not unique to Bovens. The second point seems to call abortion an action but the use of an IUD a form of omission; ensuring that implantation will not occur (to put it graphically) is not “not providing the right environment for embryonic growth”. The third point conflates OCP use and NFP use from a moral standpoint in continuing the incorrect assumption that NFP is a “mixed” contraceptive approach involving the loss of embryos. The fourth point involves the physiological fallacy that a natural conception could be timed for when the endometrium would be unsupportive of its implantation, and a repetition of the mis-application of “the action/omission doctrine”.

    The conclusion
    This article is anything but a reductio ad absurdum of anybody’s cornerstone. In regard to factual accuracy (8) and undestanding of its bases in NFP and physiology, it is itself unfortunately based on the absurdum.

    Dr Mark Whitty, MSc; Dublin, Ireland.


    (1) Hertig AT, Rock J, et al: A description of 34 human ova within the first 17 days of development. AJAnat 98; 435-493, 1956.

    (2) Roberts CJ, Lowe CR: Where have all the conceptions gone? Lancet 1; 498-499, March 1 1975.

    (3) Harris J: Stem cells, sex and procreation. Camb Q Healthc Eth12, 353-371, 2003; (page 364).

    (4) Peel J, Potts M: Textbook of Contraceptive Practice, Cambridge UP 1969.

    (5) Weismiller, D: Emergency Contraception. JAAFP 70:4; 707-714, August 15 2004.

    (6) Van der Vange N: Ovarian activity during low dose oral contraceptives. In Chamberlain G ed: Contemporary Obstetrics and Gynaecology, Butterworths London 1988 pp 315-326.

    (7) Grimes DA, Goodwin AJ et al: Ovulation and follicular development associated with the low-dose oral contraceptive; a randomised controlled trial. Obstet Gynae 1994 83 1; 29-34.

    (8) For information on physiology and NFP, the best single source is the website . Articles such as “Correlating the Signs and Symptoms of Fertility at the Vulva and Vagina” and “The Continuum” provide good summaries of decades of collaborative research. There are several summaries of effectiveness studies on the site.

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  11. Kenosis and perichoresis

    Dear Editor,

    Whilst I am an advocate for dialogue and mutual understanding and indeed have written on the possible acceptance of emergency contraception in instances of rape, I find this article by L. Bovens rather disturbing and at most insulting to the general Catholic population. Although he uses the term pro-life, this can only be an emotive attempt, rather than rational argumentation, since 'pro-lifers' have been associated with hard- line fundamentalists - which indeed in itself is unfortunate.

    Catholics do sometimes complain that using the rhythm method is in a sense hypocritical and since the intent is the same, then why not use oral contraception. They do so however in a certain aptitude of ignorance of the pharmacodynamics and pharmacokinetics of the drug. Oral contraception is intent merely on stopping the reproductive function, period. It has also been known to be abortifacient, especially when women are given the advice to take two pills the next day after a day in which they would have missed out; and even three pills if they forget taking it for two days. Perhaps there is an omission of the informed consent process on the part of the prescribers in this process.

    The rhythm method is simply a method by which couples are careful when the woman is ovulating. This can be used both for the intent of having babies or for not having them. I will restrict myself to the Catholic perspective. Being Catholics means being united as a couple. This unity must be seen in the perspective of trinitarian theology which speaks of kenosis and perichoresis. The latter is the emptying of oneself; the former is the making oneself 'one' with the other. This does not translate that therefore the couple, being one, cannot have a say in God's plan on planning their family. Where would freedom be if this were not so?

    Philosophically however it is even more problematic to think that people cannot have a say by controlling their reproductive life. Technically we can spend our whole life in bed trying to have babies, since every moment that passes is an opportunity 'lost'. Indeed this in itself is a reductio ad absurdum of Boven's argumentation, I am afraid.

    One has also to consider the reasons chosen for family planning. Not all may be justified and therefore the morality of natural family planning lies in this non-manifest agenda rather than solely in the act. Besides this there is the whole concept of one being a natural method which is inherent in human nature and understanding of its own physiology. The other is based on a physical barrier, intent on altering one's physiology and nature. This may be fine for many; it does not translate into being a moral falsehood for those who believe in the unity and agape of marriage.

    Pierre Mallia

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  12. Surprised and disappointed

    Dear Editor,

    I'd like to respond to the article by L Bowens you printed in 2006, Vol. 32:355-56.

    1. The rhythm method has been out of date for decades.

    2. The rhythm method was not a form of contraceptive. It was based on abstinence during fertile periods. (Admittedly its method for calculating those was flawed, hence point 1). Nevertheless pregnancy does not result from abstinence.

    3. Users of NFP only differentiate between fertile and infertile days. There is nothing half way, such as less fertile days. Couples engaging in sex during fertile days know to expect a pregnancy. Assumptions that they hope for or expect embryonic death (by engaging in sex on so called less fertile days surrounding high fertile days) are absurd.

    4. The author does not differentiate between natural death and induced death.

    Surprised and disappointed.

    Yours faithfully,

    Ira Winter RN MSc FCP (intern).

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  13. Absurd science

    Dear Editor,

    This article ignores up to date knowledge of the physiology of reproduction in its fascination with a mathematical and statistical model and his illogical assumptions.

    The ovum lives for 12-24 hours, and it can only be fertilised within this short time(1). Outwith the fertile time, the sperm cannot reach the ovum as the cervical mucus dries and forms a plug(2). The sperm can be kept waiting in the cervical crypts for 4-5 days maximum prior to ovulation. If a sperm reaches the ovum and fertilises it, it has shown it has been healthy enough to win the race in the last sprint to the fallopian tubes!

    There is no evidence that there is any variability of viability of the conceptus with time of fertilisation within this narrow window. The viability of the new human being is dependent on his or her completely new and unique genetic make up, which may be defective because of genetic disease carried by the gametes. It also depends on the health of its environment rather than the tiredness of the now dispensed propelling mechanism of the sperm.

    Once conception has occurred the next phase kicks into action, progesterone rises up to about the 7th post-ovulatory day then Human chorionic gonadotrophin (HCG) produced by the implanting blastocyst, maintains the corpus luteum(3). Research has revealed variant forms of ovulation and defects in implantation(4), some due to hormonal problems, a short post-ovulatory phase or problems with the receptivity of the endometrium but this is not related to the times of intercourse.

    If implantation is faulty in some way, the couple may suffer recurrent early miscarriages. These couples would therefore be wise to use the Natural Family Planning in order to achieve, rather than avoid a pregnancy, in order to increase the probability of fertilisation and subsequent success. Nature allows wastage, it can be cruel, but as yet, we have little power over it. NaProTechnology(5), which uses the science from Natural Family Planning, aims to prevent early miscarriage with hormone support and to maintain pregnancy to full term.

    I was surprised at the out of date science used in this article. We can only develop our bio-ethics in accord with the best science available at any point in time, otherwise it would certainly, as in this case, be reductio ad absurdum.

    Dr A M H Williams
    GP and Medical Advisor Fertility Care

    p.s. I could also add that though many people may use NFP for pro- life reasons, the overwhelming reason is to not separate the procreative from the unitive functions of the sexual act, but that may take a bit longer to explain.



    (3) Duncan W.C., et al, Human Reproduction, Vol. 11, No. 10, pp. 2291-2297, 1996.



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