Abortion-related issues evoke strong emotions (Image: Chip Somodevilla/Getty)

Arizona has passed a law that requires doctors who provide drug-based abortions to tell women that the process may be reversed after taking the first dose. Some claim that the science is flawed and it’s just another way of putting pressure on women to change their mind about having an abortion.

How can an abortion possibly be reversed?

A drug-induced abortion, as opposed to a surgical one, is an option during the first nine weeks of pregnancy and involves taking two drugs 48 hours apart. It is between 87 and 98 per cent effective, depending on the stage of pregnancy. Obviously, it cannot be reversed once the process is complete but it can be interrupted before the second dose is taken.

How does interrupting an abortion work?

In drug-induced abortions, the first dose is mifepristone, which causes the embryo to separate from the lining of the womb. The second drug causes the womb to expel its contents. The new law is based on an experimental treatment that involves an injection of progesterone, the hormone that normally helps maintain pregnancy. If the woman changes her mind after the first drug, the extra progesterone could undo its effects, claims the regime’s developer, George Delgado of Culture of Life Family Services in San Diego.


How effective is the abortion-interruption process?

A case series published in 2012 suggests that four of six women who changed their minds remained pregnant and subsequently gave birth. Delgado has told New Scientist that since then the approach has halted 87 abortions, with roughly the same 60 per cent success rate, although these results are unpublished.

Could the baby be harmed by the first abortion drug?

Delgado says there have been no congenital malformations or other problems at his clinic. With the two-drug abortion procedure, most of the safety concerns if pregnancies unexpectedly continue are linked to the second drug, says Patricia Lohr of the British Pregnancy Advisory Service. And progesterone, the “reversal treatment”, is given to women undergoing IVF to help maintain the pregnancy, so is also unlikely to cause harm.

So what’s the problem?

Although Delgado cites animal research in support of reversing abortions in this way, most doctors dismiss the idea that progesterone could do this. Mifepristone, the first drug, works by displacing progesterone from its receptors on the surface of cells. It then binds extremely tightly to these receptors, so an injection of extra progesterone probably has no effect, says Lohr.

Then why have some abortions apparently been successfully halted?

It may be nothing to do with the progesterone. If a woman takes only the first abortion drug, it’s possible the pregnancy would continue anyway – hence the need for the second drug. There are no reliable figures for abortion rates with a single dose of the first drug, because before the two-drug regimen was developed, doctors generally used the first drug several times.

Even with such multiple dosing, the pregnancy continued about 40 per cent of the time of the time, without the addition of progesterone. “There’s no proof that progesterone works,” says Lohr. “The only way to tell if it’s effective is by doing a randomised trial.”

How often do women change their minds after the first dose?

Delgado says surveys show that about 10 per cent of women who have an abortion feel regret afterwards, and suggests that such women might opt for his reversal procedure if given information about it beforehand. But Lohr points to a study of more than 4000 British women, which showed only one changed her mind after taking the first drug.

“If a doctor told me the abortion they were about to carry out was reversible I would feel as though they weren’t listening when I said I was not prepared to continue the pregnancy,” says Lohr. “It’s corrosive to the doctor-patient relationship, which is built on trust and a belief that the doctor is always acting in the patient’s best interests.”

How has the ruling been received?

Critics say it is part of a broader attack on access to abortions in the US. “This is another example of anti-abortion pseudoscience, which unfortunately is becoming common practice in the US,” says Marge Berer of the International Campaign for Women’s Rights to Safe Abortion.

Some US states require women to see their embryo on an ultrasound scan before the abortion, even though before 12 weeks this may require the use of a vaginal ultrasound device. Others require doctors to tell women that the fetus can feel pain during the procedure, which is highly unlikely. Lohr says: “Whether this bill stays on the books in Arizona, I think it’s likely that we will see it pop up somewhere else.”