The unknown mechanism of action of the IUD

A fellow philosopher just sent me this very interesting quote from an article in a reputable medical journal:

[I]f it was conclusively shown that the sole or principal mode of action [of the IUD] was to prevent the embryo from implanting, then this method, as in the case with emergency contraception, would be considered by the Roman Catholic church as causing an early abortion. As a result many agencies involved in the research, development or delivery of contraception prefer to leave the mechanism of action issue unresolved, which may explain why research into the contraceptive mechanisms of IUDs has been sparse in the last 20 years.

The quote’s invocation of politics fits with vague suspicions I had.

But in any case, I wonder whether leaving the “the mechanism of action issue unresolved” helps all that much morally. Suppose that prevention of implantation is morally on par with paradigmatic cases of killing an adult human. Now consider this story. You are a doctor on board a spaceship marooned on an alien planet. All your drugs have been destroyed but one of your patients is suffering severe pain. The aliens have a callous attitude to human life, but in exchange for a piece of fine art they offer you a drug. The aliens always tell the truth and they guarantee that the drug “terminates the pain.” But when you ask them about the mechanism by which it does so, they say: “Trade secret. It terminates the pain.” You try asking more general questions like: “Does it suppress pain signals in the brain?” They just say: “That would terminate the pain. It terminates the pain. Why ask more?” Then someone else in your crew asks: “Does it terminate the patient?” And the aliens say: “That would terminate the pain. It terminates the pain. Why ask more?”

The end result is that you have no idea whether the drug terminates the pain by suppressing the pain as such or by killing the patient. It is clear that in that case we should not use the drug, except as a last-ditch hope for a patient who is already dying. (I am not saying it is acceptable to kill someone who is already dying. But if someone is already dying, then one can tolerate a greater risk of unintended death.)

I am not saying, of course, that we need to find evidence against every crazy hypothesis. There is, after all, the hypothesis that ibuprofen works by annihilating the patient and calling in aliens that replace the patient with a pain-free simulacrum. The tiny but non-zero probability of that hypothesis should not keep us from using ibuprofen. But when we do not know how some drug or procedure works, and one of the serious hypotheses is that it works by killing someone, then that’s a problem.

Given the callousness of the aliens, the hypothesis that they are offering a euthanasia drug is a serious hypothesis. Likewise, the hypothesis that the IUD works primarily by preventing implantation is a serious hypothesis (see the suggestive evidence in the above-quoted paper). In both cases, then, unless we can find significant evidence against this serious hypothesis, the use of the drug or method is wrong (except perhaps in exceptional cases).

We rightly have a guilty-until-proved-innocent approach to medical interventions. Apart perhaps from exceptional cases (e.g., terminal ones), a medical intervention must be tested for its effects on the directly affected parties. The manufacturer's failure to gather data on the effects of the IUD on some of the directly affected parties, namely the embryos, means that the IUD has not been tested up to the morally required standards of testing medical interventions, and hence cannot be licitly used (apart perhaps from some exceptional cases), even absent the data that we have that is suggestive of fatal effects on those parties.

The pill

I will use the phrase "using oral contraception" (and cognates) to abbreviate the complex state of affairs of being a woman of normal fertility and using standard contemporary (not the older higher dose pill) oral contraception as the only form of contraception for the period of at least a year while being sexually active at an average sexual frequency. The following argument is sound when implicitly conditionalized on the present state of medical knowledge and technology:

1. Someone who prevents the implantation of an embryo that he or she is a parent of causes the death of his or her innocent child. (Premise)
2. It is wrong to act in a way that carries a significant risk of one's causing the death of one's innocent child without very grave reason. (Premise)
3. Using oral contraception carries a significant risk of one's causing the death of an embryo that one is a parent of. (Premise)
4. It is wrong to use oral contraception without very grave reason. (By (1)-(3))
5. Very grave reason to use oral contraception is exceedingly rare if it ever occurs. (Premise)
6. It is wrong to use oral contraception except perhaps in exceedingly rare cases. (By (4) and (5))

The same goes for the IUD. I do not know if the argument holds for implantable or injectable hormonal contraception, but at least unless one has very good reason to think that it does not, one has good reason to avoid that, too. I should add that I think marital direct contraception is always wrong, but the present conclusions are is controversial enough.

The argument has a formal feature that complicates things. The terms "significant risk" and "grave reason" are not defined explicitly. Rather, they must be taken to be partially interdefined by (2).[note 1] Thus, in defending (5), one needs to argue that what is exceedingly rare is the sort of reason that would fit into the exception in (2), where "significant risk" is the risk we get from the medical literature supporting (1).

I will not argue for (1) and (2). I think (2) is uncontroversial, and (1) will generally be accepted by pro-life folks.

We do not know exactly how often the use of oral contraception causes a failure to implant. A survey of data is given by Larimore and Stanford (2000). Hormonal contraception has three main modes of operation according to references (including product inserts in at least some cases): (a) prevention of ovulation, (b) modification of uterine environment that makes it inhospitable, and (c) modification of cervical mucus to make it harder for sperm to reach the ovum. The data in Wildt, et al. (1998) strongly suggests that sperm can travel through thick mucus. So (c) isn't a very effective method. Studies show that ovulation still occurs in 1.7-65% of cycles (see Larimore and Stanford, 2000; unfortunately, I don't know if this is for perfect use or typical use). Assume, conservatively, a not unrealistic fertilization rate of about 10% per cycle in which ovulation occurs.[note 2] Assuming independence (which isn't exactly right, admittedly), this gives us an annual fertilization rate of 2%-55% (assuming 12 cycles per year). But the established pregnancy rate for oral contraception is significantly lower than most of this range (the perfect use pregnancy rate is 1% or lower; the typical use pregnancy rates are higher), where an established pregnancy is one where implantation has occurred. So there is good reason to think that there are probably significantly more fertilizations than established pregnancies, and hence there is good reason to think that using oral contraception carries approximately a 1% to 50% chance (this will be a combined epistemic and nomic probability) per year of preventing a fertilization, and thereby causing the death of the embryo.

This will yield (3), assuming 1% to 50% counts as "significant risk" in the sense used in (2). But I think it clearly does count. A quick way to see this is to imagine that the risk is not to one's child, but to the user. The FDA would not approve a form of contraception which had a 1% to 50% annualized chance of resulting in the death of the user, and medication with that fatality rate would only be approved if the condition it treated was very grave indeed. If such a risk to the user would be unacceptable absent a very grave reason, a fortiori it would be unacceptable when the risk was to another party.[note 3] In fact, I doubt that we would approve of life-saving medication that had a 1% to 50% chance of causing the death of a bystander (imagine that it gives off noxious fumes or something).

That leaves (5) to be argued for. But that's easy. Given that the "very grave reason" would have to be one that would justify taking an annualized 1% to 50% risk of being the cause of one's innocent child's death, it seems clearly that only extreme circumstances will yield such a reason. If using oral contraception is needed to save someone's life, a case might be made (though note the caution at the end of the previous paragraph). But remember that I defined "using oral contraception" as including sex at a normal sexual frequency and with no other contraception being used. So that would have to be a case where having sex at a normal sexual frequency was needed to save a life and no other contraception was possible. Maybe if a woman had to have sex with a dictator for a year or he else he would kill her (or someone else), and if pregnancy would result in the woman's death, and if the use of non-abortifacient contraception were impossible, this could be argued to be a case like that (in the end I deny it, because it is wrong to commit adultery even to save a life). But such cases are, indeed, exceedingly rare. Perhaps saving someone from serious disability would qualify. Could "saving a marriage" qualify? I doubt it. Would it be permissible for a couple to undergo a "marriage saving treatment" that had a 1% to 50% chance of killing one of their children? And the case would have to be such that the consequences of pregnancy would be very grave, and that no other contraception was possible. (And even then it would be wrong if, as I think, marital direct contraception is always wrong—but that requires a different argument.) So I think (5) is very plausible.