The Evidence that Plan B Does Not Cause Abortions in the Fertile Window: Symposium on Plan B: Part IV

Editor’s Note: The editors present this series (read part 1, part 2, part 3, part 5,  part 6) on the recent furor over Plan B as an opportunity for our fellow pro-lifers to slow down, step out of activist mode, and enter into the conversation in a prayerful and thoughtful way.

The Church encourages conversation among faithful scientists and theologians as new science comes to light and as we deepen ethical reflection. Typically such conversations occur in academic settings, but since the recent furor pushed the issue into the open, causing much confusion and scandal, we felt it important to present the latest science and moral reflection in a context of faithful discussion.

We offer this series in a spirit of obedience to the Magisterium, and as an opportunity for faithful Catholics and people of good will to come to a greater understanding of the nuances of the Church’s teaching and the complexities of the science and art of medicine in the difficult situations involving the treatment of women who have been raped. There has been no (and will be no) revision in the Church’s teaching concerning direct abortion or contraceptive sexual acts between spouses. Both are morally illicit without exception.

As with all Truth and Charity Forum articles, opinions belong to the author alone and do not necessarily represent the official position of Human Life International.


In my previous article in this series, I summarized the scientific evidence that suggests that not all morning after pills – in this specific case, levonorgestrel – are abortifacients. In response, my critics have proposed that the numerous studies I cited do not address their specific concerns that Plan B is an abortifacient in a particularly unique way, a proposal that I will call the preovulatory use-postovulatory abortifacient hypothesis.[i]

According to this hypothesis, levonorgestrel can act as interceptive when it is administered during a brief period prior to ovulation before what is called the LH surge (days LH -5 to LH -2). Here, the drug blunts the LH surge that is normally required for ovulation but the blunting of the LH surge is not enough to prevent ovulation. Thus, an egg is released.

However, and this is the crux of the hypothesis, its proponents propose that the blunting of the LH surge would lead to hormonal changes that would detrimentally alter the endometrium preventing, if the egg is fertilized, proper implantation of the embryo. They therefore conclude that LNG is an interceptive and an abortifacient.

There is indeed data that indicates that LNG, when administered after the onset of the LH surge, is often unable to prevent ovulation.[ii] Moreover, it is clear that when ovulation occurs, Plan B does in fact blunt the LH surge.[iii] However, as I have already noted in my published work in the National Catholic Bioethics Quarterly, there is also reliable data that indicates that the blunting of the LH surge by Plan B taken prior to the surge (LH -2), even when ovulation occurs, is NOT accompanied by the hormonal changes that would interfere with endometrial function.[iv]

As Durand et al. (2010) conclude in their study of the effects of LNG ingested two days prior to the LH surge (LH -2): “The apparently normal E2 and P4 production during the luteal phase suggested a normal luteinization and corpus luteum function in LNG-ov cycles [reproductive cycles when LNG administration still leads to ovulation], which agree with the lack of deleterious effects of this hormonal contraceptive regimen on the endometrium.”[v] This finding seriously undermines the tenability of the preovulatory use-postovulatory abortifacient hypothesis, which requires that the blunting of the LH surge leads to hormonal deficiencies that interfere with endometrial receptivity.

It is especially in light of these recent findings that I claim that it is very unlikely that Plan B is an abortifacient in the manner that some have hypothesized: It would be physiologically difficult, if not impossible, for Plan B to impair the endometrium, making it unfit for implantation of an embryo, if it does not alter the post-ovulation hormonal profile of a woman when it is taken prior to the LH surge.

How then do we explain the absence of pregnancies in women who have ovulated despite their ingestion of Plan B?[vi]

One real possibility emerges from the scientific observation that eggs that are released from the ovary when the LH surge is blunted are defective. They are hard to fertilize.[vii]

Whichever explanation we use to account for the absence of these pregnancies, in light of the findings described in the Durand et al. (2010) paper, we have to rule out explanations that involve hormonal disruptions that corrupt endometrial function. In other words, we have to rule out the preovulatory use-postovulatory abortifacient hypothesis.
Next page: Hard for Some to Accept the Science–>

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  • Juan Velez

    Also as a priest and a former physician I question Fr. Austriaco’s moral conclusion and his reading of the data. St. Thomas teaches that prudence necessary for right reason and action requires seeking adequate counsel. We need to understand this subject more and anyone advising on these matters should study the largest series of 388 treated women (Noe and Croxatto, 2011).

    First, various studies indicate a shortened luteal phase length and progesterone levels when women are treated with Levornorgestrol emergency contraception (LNG EC). Below see one example.

    Second, there is overwhelming data showing that expected pregnancies are prevented even when ovulations have not been prevented, in other words when there are many likely conceptions that occur but the embryos are prevented from implanting. In 2011, Noe and Croxatto write (where FR is synonymous with ovulation):

    Eighty-two of the 103 women treated before
    ovulation completed the 5 days of follow-up, and in 63 (80%) of them, FR was
    detected. In the group that had intercourse on day -2, FR
    was detected in 22 (92%) of the 24 women who completed follow-up days.

    This scientific evidence should lead informed persons to the moral certainty that in taking LNG EC there is a good or even high likelihood of causing a chemical abortion. This does not mean that every time someone takes LNG EC an abortion will occur, but that there exists a significant likelihood.

    In sum, emergency contraception with LNG will often produce abortions and it canot be morally justified.

    In 2001 Marta Durand and colleagues studied
    45 women, and used the older LNG-EC 0.75 mg x 2 regimen.[1] She devised four
    groups of patients (labeled Group A to Group D). She found that twelve
    patients in Group A were anovulatory (80%) when given LNG-EC on Day 10, and the
    remaining three patients had shortened luteal phase and lowered progesterone
    levels. In Groups B and C (which were administered LNG upon immediate
    detection upon urinary LH and 48 hours after LH respectively), no significant
    differences on either cycle length or luteal progesterone were noted. Group D
    consisted of LNG administration in the late follicular phase (LH-3 +/- 1) which
    means that the drug was given 3 days (+/- 1 day) before the LH surge
    (determined by urinary detection of LH). Ovulation was confirmed by FR in all
    Group D patients. In other words, LNG EC administered in the late follicular
    phase did not suppress ovulation. Most importantly, Group D had deficient P4
    (progesterone) production with a significantly shorter luteal phase length.

  • Dr Peck

    In our previous article, we summarized that 80% of women ovulated despite receiving Plan B in their fertile window. We also updated the reader of the recent research that shows that Plan B has no effects on cervical or mucus and that this would not account for any of Plan B’s efficacy. Fr Austracio concludes that if Plan B does effect LH surge, it would make the ovum “unfertilizable”. He relies on data taken from a small, totally uncomparable study of infertile women by Verpoest. This research assessed LH levels in a totally different manner compared to Plan B studies (using LH found in follicular fluid) but more importantly, we can not extrapolate results on infertile women between fertility injections and compare them with “overly” fertile women taking Plan B for EC! Moreover,he asserts that one study, Durand 2010, did not show lowered progesterone levels, which provides evidence for his point that Plan B does not exert a post-fertilization effect. Although Durand 2010 did not show lowered progesterone levels, other studies did – such as Okewole, Durand 2001, and Croxatto 2004. Moreover, other corrobating factors, such as shortened luteal phase, increased vaginal bleeding, and altered LH levels were found in a variety of studies and may also be used as evidence of this post-fertilization effect.

  • Steve Mosher

    As a sometime biologist, I must agree with Father Velez here. I believe that the recently published work of Noe and Croxatto, referenced by Father Velez, elegantly–if inadvertently–demonstrates the abortifacient effect of Plan B (EC).

    [1] G. Noé, H. B. Croxatto, et al, “Contraceptive efficacy of emergency contraception with levonorgestrel given before or after ovulation” Contraception 84 (2011) 486–492.

    To summarize: Plan B given in the critical pre-ovulatory phase did not prevent ovulation. Nor does it inhibit sperm motility or capacitation. Nor is there evidence that it caused defects in the eggs released. Some conceptions should have resulted. Yet there were no successful implantations.

    The German Bishops, in approving the use of Plan B for rape victims on the assumption that it is not abortifacient, m, but only if it does not cause abortions, are approving a pill that does not exist.

    Steve Mosher

    President, PRI

  • Dominic M. Pedulla MD

    The fundamental purpose of moral certainty is frustrated when the premise one claims to be certain of — that Plan B is strictly contraceptive and not abortifacient — is itself not true. Newer data reveals Plan B is not a contraceptive at all, much less not so only some of the time. Selectively identifying only Durand’s 2010 progesterone levels as proof of no implantation defect is a bit like finding one piece of ground under a tree without any snow in a snowstorm, and claiming it is not snowing! But here even the little ice crystals on the bare ground were missed. It takes some back-round in reproductive physiology to see that not only are there numerous data — selectively ignored by Austriaco — showing progesterone deficiency around implantation, but even the one he cited had shorter luteal phases which most certainly DO REPRESENT a hormonal defect jeopardizing the embryo. Nearly all ovulate, sperm are not hindered in reaching the egg, and luteal phase defects at the crucial moment of implantation…..yet no abortifacient effects? And moral certainty too? Really?

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  • http://www.facebook.com/erika.vandiver Erika M Vandiver

    It’s hard for some to accept what passes as science, but is really lies or distractions. If Plan B is really non-abortifacient, & only anti-ovulatory why do some women ovulate anyway? What effect does Plan B have between conception and implantation: a phase lasting anywhere from 5-12 days? Is a conceived embryo, not yet implanted, less worthy of protection and respect simply due to its method of conception? How can ER doctors know whether a woman was raped or just saying so in order to get emergency contraceptives? Until these questions can be answered sufficiently, then Plan B is NOT a plan that should be endorsed by the Church or pro-lifers.

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