Do modern contraceptive pills include an abortifacient effect in their mechanism of action?
Gonzalo Herranz, 1994.
1. The main question asked is whether the mechanisms of action of modern oral contraceptives ('contraceptive' pills) involve an early abortifacient effect.
2. The most common modern oral contraceptives are characterised by a very low content of synthetic oestrogens, in order to avoid the range of undesirable effects, due to their high oestrogen content, typical of oral contraceptives used in the early years of oral contraception. (In contrast, morning-after pills contain very high amounts of hormones).
3. The review of the medical bibliography , published in the last decade, does not provide much data on topic. In contrast to other aspects of the pharmacodynamics of oral contraceptives, on which there is an abundance of very detailed and precise work by research (e.g. on the contraceptive efficacy rate or on the intensity of certain undesirable effects - such as the metabolic impact on lipids and carbohydrates, blood coagulability disorders, clinical course of diabetes, cardiovascular disorders, endocrine changes, neurological disorders, sexually transmitted diseases - and on the beneficial non-contraceptive effects (reduced incidence of breast and ovarian cancer),1 very little work has seriously addressed the study of the mechanisms by which modern preparations exert their contraceptive effect.
4. One can suspect that this lack of interest is based on ideological and economic policy reasons. It is not in the interest of the pharmaceutical industry and the major agencies promoting hormonal contraception to clarify precisely to what extent the different components of the total contraceptive effect of the various types of modern pills (inhibition of ovulation, modification of the molecular texture of the cervical mucus which becomes impenetrable to sperm, uptake and transport of the oocyte by the tube, deficient training of the sperm, inhibition of blastocyst nidation by alteration of the endometrium) are to be treated. It is preferred to leave them in the shadows and deal only with the full effect2. Informing the public about, for example, the anti-inflammatory effect of the various contraceptive formulations could create an aversion to the use of these preparations in a very large section of society, which would have a negative impact on sales or on population policies.
5. To the deliberate purpose of not researching and not informing about this dark side of contraception, there has been associated the will of manufacturers and many doctors to ignore the biological and ethical significance of the human embryo in the days between fertilisation and the end of nidation. This has had two consequences: one is to eliminate the pre-natal embryo from the diary of the scientific research on contraceptives; the other is to spread the feeling that its existence is ethically irrelevant3 .
6. There are few, and in some cases contradictory, data available on the contribution to the total contraceptive effect of the various elements mentioned above.
Some authors consider that the anti-implantation, or early abortion, component of oral contraceptives is negligible from both a biological and a moral perspective4. Other authors, on the other hand, tend to underline that, since the changes that the endometrium undergoes are incompatible with nidation, although in fact they only act as a determinant of contraception on a small number of occasions ( issue ), they imply a desired early abortive effect which, if known, would imply a moral decision, always and in any case significant5.
7. What is actually known about this frequency? The existence and intensity of the nidation inhibitory effect (early abortifacient effect) has recently been reviewed in general terms by K.M. Severyn6, and in a more detailed study by W. Rella7. The latter author's monograph should be read for an accurate overview of topic, especially the section dealing with endometrial and tubal factor alterations under steroid contraceptive ingestion (pp. 45-54).
A review of the biochemical and regulatory mechanisms triggered by modern oral contraceptives suggests that the antinidatory action contributes to the contraceptive effect to different extents, depending on the compounds used, the dosage and duration of use, the individual response of the users, and other circumstances.
Rella concludes that, in the course of continuous contraception, under real conditions of employment of the oral contraceptives currently used by unselected groups of women, the rate of ovulatory leakage is as high as 10%. There are, therefore, strong reasons to conclude that, as a result of such a leakage, at least one case of pregnancy termination due to nidation inhibition would occur in the course of a woman's active sexual life as a result of the anti-nidation effect of the combined pill. In contrast, when the mini-pill is used, and as a result of the higher frequency of ovulation that is inherent to it, a five times more intense antinidating effect is to be reckoned with. The proportionally stronger antinidating action is the one that occurs in the weeks following the discontinuation of prolonged contraceptive treatment, as there is then a dissociation between the rapid recovery of ovulatory function and the slow restoration of endometrial function. In 20% of cases, this dissociation leads to an ovulatory/endometrial discrepancy in the cycle following discontinuation of contraception: if fertilisation then occurs, it is followed by rejection of the blastocyst by the arreceptive endometrium7.
bibliography and notes
(1) This can be seen in the contents of the most recent supplements to the American Journal of Obstetrics and Gynecology (DeCherney AH, Speroff L., eds. Next generation of contraception: oral contraceptives in the 1990s. Am J Obst Gynecol 1992;167:1159-1202. Burkman RT, ed. Desogestrel: a progestin for the 1990s. Am J Obst Gynecol 1993;168:1009-1052.
Grimes DA, Mishell DR, jr, Speroff L., eds. Contraceptive choices for women with medical problems. Am J Obst Gynecol 1993;168:1979-2048. Bialy G, Haseltine F, Alexander NJ, Burnhill M. Preventing unintended pregnancy: The role of hormonal contraceptives. Am J Obst Gynecol 1994;170:1483-1590).
In none of these monographs is there any allusion to the possible abortifacient effect, except in the article of Lobo RA and Stanczyk FZ: New knowledge in the physiology of hormonal contraceptives (Am J Obst Gynecol 1994;170:1499-1507), in which, however, it is concealed thanks to the tactical handling of scientific language: "Low doses of progestins produce an antifertility effect but not an antiovulatory effect. Progestins cause turbidity of cervical mucus, inhibit spinnbarkeit, prevent sperm penetration, and blunt the karyopycnotic index. Effects on the endometrium include suppression of glands, resulting in a decidualized reaction with atrophic changes and an almost denuded endometrium". No mention is made of the obvious consequence that such a modified endometrium becomes refractory to embryo nidation: the anti-implantation, early abortifacient effect of these contraceptives is concealed.
(2) This can be seen in a kind of programmatic statement, made more than 25 years ago: "Concerning the myriad steps and interdependent actions which must take place for conception it is almost unbelievable that the species has been able to reproduce itself at a rate which threatens world safety. It is generally accepted that the more complex an operation, the more readily its ultimate function can be frustrated by trivial manipulation of the balanced interaction of its components. Similarly, in the comparably intricate process of human reproduction in the female [...] the exact stage of the reproductive process which is being influenced is immaterial to the acceptance of this idea as a working hypothesis. [...] in the solution to the problem of population control, the concept of ovulation suppression should be replaced by this broader concept: creating an estrogen-progestogen imbalance". Rudel HW, Martinez-Manautou J. Hormonal fertility control: A working hypothesis for population control. Fertil Steril 1967;18:219-221.
(3) One story, concerning intrauterine devices, accurately illustrates the tactic of volatilising ethical issues through the manipulation of language. In a review article (Tatum HJ, Connell EB. A decade of intrauterine contraception: 1976 to 1986. Fertil Steril 1986;46:173-192) the authors report how IUDs were cleared of the accusation of abortifacients. But the accusation is not rejected in a scientific way, providing evidence that the different types of IUDs act preconceptionally or invalidating the data that support the anti-conception action: the refutation is based on an accommodating redefinition of the words: "As long as IUDs have been used for contraceptive purposes, there have been allegations that they act primarily as abortifacients. This concept has been publicized widely by certain religious groups who have therefore proscribed the IUD as an acceptable means of controlling fertility. However, accurate definitions of the terms 'pregnancy' and 'abortion' and recent scientific data should help to dispel this misconceptions and misinformation which have, in the past, clouded the entire issue of the contraceptive mechanism(s) of action of the IUD.
The American College of Obstetrics and Gynecology (ACOG) in 1972 published its book Obstetric-Gynecologic Terminology. In this text, 'conception' is defined as 'the implantation of the blastocyst.' It is not synonymous with fertilization. Pregnancy' is defined as the 'state of a female after conception and until termination of the gestation. [...] The same issues were addressed in September 1985 at the meeting of the International federation of Gynecology and Obstetrics (FIGO) in West Berlin. At that time, the Committee of Medical Aspects of Human Reproduction, chaired by M.F. Fathalla, M.D., of Egypt, was charged by the FIGO Board, in response to a request from the World Health Organization (WHO), to develop an accurate definition of pregnancy. The Committee agreed the following: 'Pregnancy is oly established with the implantation of the fertilized ovum.' Based upon the above definitions of 'conception' and 'pregnancy,' an abortifacient acts to interrupt a pregnancy only following implantation.
On the scientific side, a recent publication by Segal et al. reported on sequential serum levels of human chorionic gonadotropin in IUD wearers. He and his co-workers reported: 'The study demonstrates that IUD users do not retain their natural fertility, and that IUDs do not exert their antifertility effect as abortifacient agents.' They conclude: 'If a confirmed pregnancy is detected in a IUD user, it must be assumed to represent and isolated case of contraceptive failure.'
It is to be hoped that these official definitions and the new scientific data will provide a realistic and scientific foundation for a clearer understanding of the mechanism(s) of action of IUD among the lay public, theologians, politicians, and health care providers in general".
The argumentative manipulation is obvious: the redefinition of words allows the biological reality and its moral significance to be ignored. Something fundamental has been left out: the decisive first days of the floating but incredibly active existence of the pre-implanted embryo. Nothing is said about what happens to the embryo between fertilisation and nesting: neither its biological entity nor its ethical status. It seems to be enough that experts and official authorities have decided to ignore its existence. This is an unscientific, manipulative attitude, because it is not based on observation of the facts, but on their partial, capricious and voluntarist suppression.
(4) This is the case, for example, in the report requested to a Commission of the Katholische Ärztearbeit Deutschlands by the German Episcopal lecture on the antinidatory or early abortifacient action of modern contraceptives and intrauterine devices Anonymous. In their reply (Gutachten der Katholischen Ärztearbeit Deutschlands zu Wirkweisen ovulationshemmender Präparate und der Intra-uterin-pessare. Renovatio 1986;42:56-60), the Commission absolves the different types of modern oral hormonal contraceptives of any abortifacient action. In the two foundations of report , the possibility of an early abortifacient effect is categorically and a priori denied. The first one states: "However, the changes in the pregnancy test are, in the case of sequential contraceptives, especially in the case of normophasis, which are naturally present in normal pregnancies, so that the implantation process in these cases must at least be carried out as a matter of course. Im übrigen muß aber bemerkt werden, daß diese hypotetische zuzätzliche Mechanismus nicht zum Tragen kommen kann, da praktisch wegen des Ausbleibens der Ovulation keine befruchtungsfähige Eizelle vorhanden ist". The second says: 'The gynaecological test is changed, however, because the synthesised hormone is no longer used in the normal cycle, but because it is not possible for an oocyte to enter the body and grow. However, this means that, above all, the changes to the 'peripheral mechanisms of action' in the bloodstream are unable to detect its hypothetical effect, as it does not reach its peak due to the safe and reliable ovulation and the blood flow to the sperm cell.
And it adds in the final answers to some questions raised by report: "Auf Veröffentlichungen über mehr oder weniger hohe raten von Nidationshemmung in Wirkung der oralen Kontrazeption ist festzustellen: [....] The new, lower-dosed ovulation hormones - and this also applies to the pregnant women - are undesirable for this purpose (the nidation has a right to be effective). Es ist richtig. daß es zwar es verschiedene Untersuchungen gibt, in denen die Mainung vertreten ist, daß -jenach Präparat- bei einem gewissen Prozentsatz an Frauen die Ovulation nicht gehemmt ist (ca. 5%). [...However, this means that in these cases, however, there is no risk of ovulation because the nidation has not taken place; vielmehr ist es ist es so, daß die Spermatozozoenascension durch die bereits oben erwähnte und durch die Hormone (Gestagene) der "Pille" bedingte Verfestigung des Schleimpfropfes im Halskanal der Gebärmutter verhindert wird. Es bedarf also keiner Nidationshemmung, weil keine Befruchtung stattgefunden hat".
This interpretation, absolving of any anti-inflammatory effect, does not seem to be supported by the data available at bibliography which, even if only indirectly, tries to quantify the components of the total contraceptive action.
(5) See, for example, William E. May (Reverencing Human Life in Its Generation, in The Pope John Center. The New Technologies of Birth and Death. Medical, Legal and Moral Dimensions. The Pope John Center, St. Louis, 1980: 56-79), especially under the heading Contraception and Reverence for Human Life in Its Generation , when he states: "Since users of these pills cannot know how they will 'work', they manifest a willingness to accept abortion, provided they know that the pills work in this way. At present most people are ignorant of this, but such ignorance is vincible" (p. 72).
(6) Severyn KM. Abortifacient Drugs and Devices: Medical and Moral Dilemmas. Linacre Quart 1990;57(3):50-69.
(7) Rella W. Die Wirkungsweise oraler Kontrazeptiva und die Bedeutung ihres Nidationhemmenden Effekts. Wien, IMABE, 1994. ISBN 3-900538-48-4. The author says in his essay of a conclusive judgement (pp 60-61): "In Zusammenschau aller vorgebrachten Daten, Argumente und Hinweise kann in Hinblick auf die mögliche nidationshemmende Wirkung steroider Kontrazeptiva folgendes Urteil abgeben werden:
Die Rate an Durchbruchsovulationen unter Alltagsbedingungen in einem unselektierten Kollektiv von Probandinnen beträgt bei Anwendung der heute gebräuchlichen Kontrazeptiva rund 10%. Die Wahrscheinlichkeit, daß zum Zeitpunkt der Durchbruchsovulation infolge vorübergehenden Wirkungsverlustes des Kontrazeptivums auch die Zervixschleimbarriere durchlässig ist, kann in Ansehung des Dosis-Wirkungsunterschiedes zwischen zentralem und periphererem Zielorgan mit rund 20% angenommen werden. Weiters beträgt die Fecunditätsrate pro Ziklus unter Normalbedingungen, unter Einbezug des natürlichen Abgangs von Embryonen, altersabhängig pro Zyklus 20-25%. Infolgedessen wäre ohne Berücksichtigung einer nidationshemmenden Wirkung unter Einmahme sog. Ovulation of oocytes with a fertility rate of 0.4% to be rejected, e.g. 1 pregnancy in 250 cycles or in 18 years. Das entspricht, berechnet auf 100 Frauenjahre, einem Pearl-Index von 5-6. Dieser Wert liegt um mindestens das Zehnfache höher als der für Kontrazeptionspillen üblicherweise angegebene Index. This means that only one of the 10 children who will be born at the beginning of an epidemic of over-ovulation will be born into the world, while the remaining nine will be born as a result of nidation. In other words, every woman, whose contracting party, from which she has always, in total, over 18 years old, has to refuse to accept the fact that, in the event of an unequal distribution of wealth, she has been able to achieve a certain degree of freedom of movement. Der Beitrag der Nidationshemmung zur schwangerschafts-verhindernden Wirkung der Kombinationspille beträgt daher rund 2%, während 98% ihrer Wirkung auf anderen Ebenen stattfindet. Für die bei uns (nur in ca. 1% der Fälle) verwendete Minipille muß eine höhere Nidationshemmungsquote angesetz werden, entsprechend den rund 5fach häufigeren Ovulationsereignissen. Der Beitrag der Nidationshemmung dürfte in diesen Fällen 10% betragen. A more 'numerical' significance is that the nidation rate after the start of a longer hormonal phase of contraception. For about 20% of women, during a period of 3-6 weeks, starting 2-3 weeks after the start of the pill period, a "100%" nidation rate is to be rejected, so that other protection mechanisms, in particular the cervix-barriers, can also be eliminated as well".