The copper IUD is NOT an abortifacient

Getting the facts straight

Multiple Republican state officials, emboldened by the leaked Supreme Court Ruling on Roe, are participating in cancelling contraception one-upmanship. Some states, like Missouri, have already done their homework in advance, with a law on the books that could ban post-coital contraception (the morning after pill) and IUDs if Roe falls under the mistaken belief that they are abortifacients. Even though there is no evidence these methods of contraception cause an abortion, the Supreme Court decision in Burwell v. Hobby Lobby stated that if you believe something is an abortifacient, then it is an abortifacient.

By that logic malpractice shouldn’t exist. “Well, your honor, I believed that ice cream would treat appendicitis.” 

But this is about power and punishment, not about medical care. 

There is a lot of propaganda here, and that is the point. Propaganda doesn’t have to change minds to be effective, it just has to make people uncertain, leading them to adopt a neutral stance.

When I originally thought about writing a primer on IUDs, I wondered if there was really any value in it? I knew it wouldn’t change the minds of the forced birther chorus in the courts or in Federal and State governments, but then a few people on Twitter said they would appreciate it. And I thought about it some more, and I realized that if you are a reader of mine, then like me, facts matter to you even if they don’t matter to our highest court and many of our politicians. Also, many well-meaning people are going on podcasts and tweeting and getting it wrong, so this may at least arm you to hold them accountable. And finally, maybe you have a family member or friend affected by the propaganda, and maybe what you learn here might help with come conversations. 

Here I am just going to address the copper IUD, because different methods of contraception have different methods of action. If people find this interesting enough (you can let me know by liking the post, sharing it, and if you are a subscriber, by telling me in in the comments), then I will do another one for the Mirena IUD and for each method of post-coital contraception. 

The History of the Copper IUD

The first IUD was described in the early 1900s, and over the years a variety of devices were used, but in 1969 a Chilean physician, Dr. Zipper discovered that copper was toxic to sperm. I don’t know why, but I love that his name is Dr. Zipper. Maybe because zippers are usually metal or that a zipper isn’t a bad analogy for long acting reversible contraception. 

Before the copper connection was identified, IUDs were made of metal or plastic, and there were issues with both. Plastic IUDs were more popular in the United States, in part I’m guessing because plastics were the cool new tech (I’m sure there is a joke from The Graduate in here), but one issue is the plastic devices basically had to fill the inside of the uterus to be effective, and larger devices caused more cramping and bleeding and were more painful to insert. Adding copper to the IUD meant the size of the IUD could be decreased, improving user experience. The first copper device was the Copper 7 with 200 mm2 of copper, with a failure rate of 2-3%. In the mid 1970s, researchers found that by increasing the amount of copper, they could further reduce the pregnancy rate, leading to the Copper T 380A (with 380 mm2 of copper). The Copper T380A is the Paragard on the market today in the United States. The failure rate of the Paragard is 0.8%, meaning if 1000 people us it for 1 year, 8 will get pregnant. 

The Definition of Pregnancy

Medicine defines pregnancy at implantation. There are two reasons for this. One, there are no reliable tests that can tell us if fertilization has happened until implantation occurs, and the other is the fact that on average approximately 50% of fertilized ovum are so genetically unstable that they can’t implant, so they aren’t even potential pregnancies.

But I know that a minority of people define pregnancy as fertilization, so here we’ll address the effect of the copper IUD in implantation. 

Why Do So Many People Believe that Copper IUDs (and all IUDs) Affect Implantation?

Well…someone said it did in the 1960s and it became canon. 

This is a dirty little not-so-secret of medicine. Someone writes something once in a textbook…and it sticks! Whether it was true at the time or not doesn’t really matter, because undoing incorrect canon, no matter its origin, is hard. 

The original research that suggested IUDs were abortifacients came from a rat study that showed silk thread in the uterus (as a proxy for an IUD) prevented implantation. However, it turns out that when it comes to a foreign body in the uterus, rats behave very differently than humans. In fact, many animals respond to IUDs in markedly different ways. With rats, an IUD prevents implantation of a fertilized embryo, but with cows it’s an impact on the corpus luteum, and with sheep the IUD creates an inflammatory response that blocks sperm. The more you know.

Unfortunately, getting everyone to take a step back and realize the original data wasn’t fit for a human comparison was hard. People don’t like when science changes because of new data, and doctors and researchers are sadly not always an exception here.  

So How Does a Copper IUD Work?

The IUD itself is a foreign body, triggering the uterus to create an inflammatory response that damages sperm and ovum (an unfertilized egg). Because the inflammatory response in the lining of the uterus is profound, many people make what seems like a logical conclusion that the inflammation could be so severe that it would prevent implantation of a fertilized embryo. The other mechanisms of action for copper IUDs are believed to be the copper affecting the cervical mucus to prevent the sperm from getting to the uterus as well as copper being directly toxic to sperm and ovum.

Multiple studies have looked at whether or not sperm makes it to the oviducts (Fallopian tubes) for people with copper IUDs and if it does, is it damaged? This is done with studies involving insemination or timed sex and then flushing the uterine cavity to retrieve sperm. Some studies have also been done when surgery was planned so the oviducts could be removed and evaluated directly for sperm. The data shows that in some cases no sperm was recovered at all, or if it was, it was often severely damaged. As you can imagine, these studies are hard to do because they require people using IUDs to participate in a procedure that might be uncomfortable, or finding people willing to do this right before a hysterectomy or having their oviducts removed. Consequently, there aren’t many studies and the numbers of people who enrolled in each one are relatively small. And not every study looked at whether the sperm that made it was damaged, just if there was sperm. But what we know from this data is that copper IUDs have a profound effect on the amount of sperm that makes it to the uterus and for the sperm that does run that gauntlet, a lot is damaged and not capable of fertilizing an ovum.

Since we can’t be definitive about the spermicidal effect being the ONLY method of contraception, we can look for studies that aim to find ovum and/or embryos floating in the uterus or oviducts. Two studies here show either no eggs recovered in the uterus or a significant reduction (30% versus an expected 57%) and in many cases the ovum were damaged. So copper IUDs also damage eggs and/ or prevent their passage to the uterus. 

As ectopic pregnancy rates are lower for people using IUDs, that also provides indirect evidence for an effect on sperm and/or the egg. Fewer fertilizations also mean fewer chances for an ectopic pregnancy. 

Among studies that look to recover embryos from the uterus in copper IUD users, no fertilized ovum (egg) been recovered. Admittedly, the numbers in these studies are low.

And finally we can look at studies that look for markers in the blood from a fertilized ovum, basically super early pre-implantation pregnancy tests. The problem here is that many of the studies use older technology or tests from the late 1970s or the early 1980s. And there is a concern the inflammation from the IUD could impact the results, so additional tests are needed to understand the potential impact of inflammation from the IUD. There are 19 studies and 5 show that fertilization could theoretically happen with a copper IUD, but at a much lower rate than without an IUD, and 14 that show no sign of fertilization or fertilization at the rate expected for the failure rate of the IUD. For example, in one study, 4% of tests showed evidence of fertilization with this not-sure-if-it’s-accurate early pregnancy test, but that was with a Nova-T device, which has a failure rate of 2-3%. Another study found a 0.9% positive early pregnancy test rate with two copper IUDs (failure rate of these copper IUDs is 0.8%). As 50%, but potentially up to 80%, of embryos don’t have the potential for  implantation, given the small numbers of positive tests it isn’t unusual a clinic pregnancy didn’t result. 

These blood tests are essentially unprovable, meaning we have there is no way know if this testing is truly a valid way to show an effect on implantation. The test that needs to be done is to use one of these hormone tests and then study people with a copper IUD and people with a  copper IUD and tubal ligation as a control. That way any effect of the copper on the hormone test can be controlled for. Ideally it would be paired with flushing the uterus to look for embryos. Those with a copper IUD and a tubal ligation would not be expected to have any pregnancies, so they are the perfect control group. 

Post-Coital Effect

The copper IUD is a highly effective post-coital contraceptive. The pregnancy rate if inserted within 5 days of the last act of unprotected sex is about as close to 0% as a method can be. A couple of recent studies show that it may be effective for even longer, up to 14 days since the last episode of sex. 

Does this mean that the copper IUD definitely affects a pre-implantation embryo if inserted as a post-coital contraceptive?

There isn’t enough data to support that claim, but these studies open the door to the possibility of an impact on a fertilized ovum with post-coital contraception. More data is definitely needed.

But the package insert says there could be a post-fertilization effect?

Yes it does, those are legal cover-your-ass documents and not scientific literature. It actually costs a money to change the package insert, and the drug companies have little incentive to do this even when it is incorrect. This information is not based on human studies that show a pre-implantation effect. 

The people making the claim need to offer proof

There is no robust data that proves a copper IUD has any effect post-fertilization, meaning it doesn’t affect pregnancy by any definition.

• No fertilized ovum has ever been recovered from studies looking at copper IUDs.

• There is of yet no blood test that can definitively prove fertilization has occurred when the embryo is still free floating in the uterine cavity and yet to implant, so the 5 out of 19 studies that show a potential effect on fertilization should be considered exploratory at best.

• The post-coital potential effect on a fertilized ovum is not definitive. 

• As failures happen, meaning pregnancies in the uterus, that speaks against a significant post-fertilization effect

• The most likely method of action is an intense effect on the sperm and ovum. 

If politicians wanted to be accurate and make an ethical claim about a post-fertilization effect, instead of cherry picking and torturing older data they’d fund a definitive study. Because wouldn’t it be great if you could prove the Copper IUD didn’t affect implantation? Then phew, people could have a highly effective contraceptive that didn’t affect implantation!!!!

Except it’s not about abortion, it’s about banning contraception and dismantling a lot of other rights. Abortion is just the trial balloon. The right wing doesn’t care to know the medical truth about a contraceptive, because the only truth that matters is that coming down hard on abortion raises money and gets out the Evangelical vote, or confuses enough people that they question IUDs or they get sick of hearing about abortion and they they think, often erroneously, “This doesn’t apply to me.” Or they just don’t even think about it because they have other things on their plate and the propaganda made them tune out. 

So that’s the summary of what we know. No study has ever proven an impact of the copper IUD on implantation. Is it possible there is an effect? Sure, anything is possible. It could also work by tiny fairies who are attracted to the copper and enter the uterus and kill the sperm. No one has proven that doesn’t happen. 

But until we have science that says otherwise, and if you can prove the fairies exist by God I will believe in them, we need to stick to the facts that all the data shows the copper IUD works by preventing fertilization either by preventing sperm from getting into the uterus, slowing or damaging sperm that makes it past the cervical mucus, and/or by damaging ovum. 

The people making disinformation about abortifacients into law are in the enviable position that they don’t have to prove they are right. But we should ask them to do just that. Instead of printing their lies or letting them go unchallenged on television, our politicians and journalists need to step the fuck up and get comfortable defending abortion and contraception with grown up words. 

There is nowhere else in medicine where we would accept this kind of scant data as acceptable. Imagine you have an abscess and all the textbooks and the World Health Organization said the treatment is surgery to drain the abscess. There are several good studies showing surgery is the best option. In fact, given the studies, your doctor would probably be sued successfully if they didn’t do surgery, because surgery is the standard of medical care. 

Now imagine your doctor says the following, “All the good studies teem me I should treat your abscess with surgery, and these are very good studies, no question. However, 5 studies out of 19 that used technology that we don’t even know is accurate suggests that maybe surgery is the wrong choice and that ibuprofen is the treatment. And another study, that wasn’t designed to show how effective ibuprofen is for an abscess, leaves the door open to maybe ibuprofen working for very few people, but we don’t really know.”

And your doctor continues, “So today is your lucky day. I am not going to follow the standard of medical care because the courts don’t give a rat’s ass. You just won the ibuprofen lottery.” 

Even if we raised enough  money for a study to prove the mechanism of action for the copper IUD once and for all, it wouldn’t matter, because those who seek to ban abortion and IUDs don’t care. Facts are as bothersome as a fly. Something to be waved off or squashed. 

The World Health Organization states the effect of a copper IUD is pre-fertilization, meaning effect on sperm and/or ovum. All the concrete data shows no post-fertilization effect. And until we have data that says otherwise, we should stick with the facts. 

References

Kristina Gemzell-Danielsson⁎, Cecilia Berger, P.G.L. Lalitkumar. Emergency contraception — mechanisms of action. Contraception 87 (2013) 300–308.

Irving Sivin and Istva´n Bata´r. State-of-the-art of non-hormonal methods of contraception: III. Intrauterine devices. The European Journal of Contraception and Reproductive Health Care, April 2010;15:96–112.

Marı´a Elena Ortiz, Horacio B. Croxatto4Copper-T intrauterine device and levonorgestrel intrauterine system: biological bases of their mechanism of action. Contraception 75 (2007) S16–S30.

Leopold Videla-Rivero, Juan Jo Etchepareborda, Esteban Kesseru. Easrly chorionic activity in women bearing insert IUD, copper IUD, and levonorgesrel-releasing IUD. Contraception  AUGUST 1987 VOL. 36 NO. 2.

Turok DK, Gero A, SImmon RG et al. Levonorgesrel vs. copper intrauterine devices for emergency contraception. NEJM 2021;;384:355-44.

Ivana Thompson, Jessica N Sanders, E Bimla Schwarz, et al. Copper intrauterine device placement 6–14 days after unprotected sex. Contraception. 2019 Sep; 100(3): 219–221.