The Abortion Pill is not always ‘effective’.

Medical Abortion (MA), aka the abortion pill, doesn’t always work; it is well-established that MA has an expected and commonly occurring treatment failure rate of about 5%. Meaning that as many as 1-in-20 pregnant women using abortion pills will subsequently need additional medical treatment for complications arising from an incomplete abortion.

Medical abortion treatment failure means either a continuing pregnancy or, more likely, retained products of conception (RPOC), fragments of the embryo/fetus and/or placenta remaining in their uterus after taking both sets of the tablets, mifepristone and misoprostol. Women for whom the abortion fails, will need to seek further medical treatment to prevent ongoing bleeding and the risk of infection.

There are three main treatments for retained products of conception: expectant management in which the medical team will adopt a wait-and-see approach; administration of an additional dose of misoprostol; or surgical evacuation (ERPC).

Abortion advocates promote medical abortion as being ‘effective’, usually without qualifying the level of efficacy. In the past this didn’t matter so much because the abortion procedure was performed in a clinical setting, the abortion provider’s own facility. The protocol then, was to only discharge a woman after ensuring that the abortion was complete. For those cases in which the medical abortion was not complete, a surgical procedure would normally be performed. These cases would subsequently be reported as having been a complete abortion, hence the use of the word ‘effective’.

Times have changed, most abortions in the UK are now self-managed by women at home, remote from the prior watchful attention of the abortion clinician. That responsibility now falls on the woman herself, she is the one that needs to determine if her abortion is complete and if not to then seek medical attention.

It is very important to note that the rate of medical abortion treatment failure is intrinsic to that treatment; it is what it is, and it doesn’t depend upon location or on who is administering the tablets. It will sometimes fail, failure will require further medical attention, and we cannot predict for which woman it will fail. The rate of failure increases with each increasing week of gestation – worth noting because advocates are now pressing for self-managed medical abortion to be permitted beyond the current limit of 9 weeks 6 days (in England and Wales).

Stated rates of treatment failure.

The following is a quick summary of how this known failure rate is noted by the NHS, by abortion providers, and those who manufacture the abortion pill.

BPAS notes on its website the following “significant unavoidable or frequently occurring risks”:

  • Continuing pregnancy (less than 1 in 100)
  • Retained products of conception – where the pregnancy is no longer growing but some of the pregnancy tissue is left behind in the womb (2 in 100)

MSI Reproductive Choices says the possible complications and risks of medical abortion include:

  • Treatment failure (continuing pregnancy) – uncommon (affects 1 in 100 people)
  • Incomplete abortion – uncommon (affects 3 in 100 people)

(Note the incorrect use of ‘uncommon’, NICE denotes rates of 1 in 100 to 1 in 10 as ‘common’)

Marie Stopes Australia reported the following outcomes for medical abortions performed in its centres in 2020:

  • 0.53% continuing pregnancy
  • 4.95% incomplete abortion

Ranbaxy (UK) Limited, the manufacturer of Medabon, the mifepristone/misoprostol combination treatment used by BPAS, states in its SmPC (summaries of product characteristics) that there is a non-negligible risk of treatment failure:

  • The non-negligible risk of failure, which occurs in 4.5 to 7.8% of the cases, makes the follow-up visit mandatory in order to check that abortion is complete. The patient should be informed that surgical treatment may be required to achieve complete abortion.

Linepharma, the manufacture of the mifepristone used by MSI Reproductive Choices, includes a similar warning in its SmPC:

  • The non-negligible risk of failure, which occurs in up to 7.6% of the cases, makes the control visit mandatory in order to check that the expulsion is completed.

The NHS states that before 14 weeks of pregnancy the main risks of medical abortion include:

  • needing another procedure to remove parts of the pregnancy that have stayed in the womb: this happens to about 70 out of 1,000 women.

The New York Times recently published a piece summarising the findings from 101 studies covering 124,000 first trimester abortions performed in 26 countries over the last 30 years. The reporters state:

  • “And while the pills are about 95 percent effective, about 3 to 5 percent of patients need an additional procedure to remove remaining tissue or terminate the pregnancy.”

Freedom of Information responses from NHS Trusts in England show that 5.9% of women using medical abortion are subsequently treated in hospital for complications arising from an incomplete abortion, including retained products of conception, haemorrhage, and infection.

A research paper by Niinimäki et al., stated that the complication rate after a medical abortion was 20%, and some still cite this, often using the headline ‘one-in-five women will suffer a complication’. This rate was contested at the time of publication, and it remains a significant outlier when compared with all other sources, e.g., those above. It is for this reason that we do not include this in our analysis.

In summary the above noted rates of failure are:

OrganisationStated rate of failure (medical abortion)
BPAS3 in 100
MSI RC4 in 100
Marie Stopes Australia5 in 100
Ranbaxy4 to 7 in 100
Linepharmaup to 7 in 100
NHS7 in 100
New York Times5 in 100
FOI investigation6 in 100

Why does this matter?

It matters because women are self-managing their abortions at home and as many as 1-in-20 of these women will experience an incomplete abortion. Since January 2019, across England and Wales, 500,000 women have self-managed their abortion at home. As many as 25,000 women have by now suffered the complication of an incomplete or ineffective medical abortion and needed to seek medical intervention.

A woman can only really give her informed consent to a self-managed medical abortion at home if she is told that abortion treatment failure is common, occurring in at least 1-in-20 cases, and that such failure will require her to seek medical attention at her local hospital or to return to the abortion provider’s facility.

2 thoughts on “The Abortion Pill is not always ‘effective’.

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  1. Very clear and informative with really well judged tone if I may say so. 



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