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Last week I talked about IUDs. But there are still a number of myths and misperceptions about them. I covered some of them in my last book, "Don't Put That in There, and 69 other sex myths debunked". But all of you didn't buy the book. Not that you shouldn't – you should! Go ahead! I'll wait.

Even if you don't, though, IUD myths are the topic of this week's Healthcare Triage.

Those of you who want to read more can go here:

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics

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Last week I talked about intrauterine devices, or IUDs.  There are still a lot of myths and misperceptions about them.  I covered some of them in my last book, Don't Put That in There and 69 other Sex Myths Debunked.  Not all of you bought it.  Go ahead; I'll wait.  Even if you don't, though, IUD myths are the topic of this week's Healthcare Triage.


Myth number one.  IUDs are abortion-causing contraption.  IUDs don't cause abortions.  Some people believe that all an IUD does is cause a fertilized egg to die, and that's not the case.  A study published in 1985 monitored daily blood samples in women over a 15-month period to see if they ever showed any signs of pregnancy.  
Three groups of women were followed.  The first was women with IUDs.  The second was women trying to get pregnant, and the third was women who had their tubes tied.  The only women who ever showed the hormonal surge consistent with fertilization were in the group trying to get pregnant.  

Another study published in the same year used an even more sensitive laboratory test to look for a hormonal surge consistent with pregnancy.  It found that in only one percent in one hundred cycles of IUD users did fertilization occur.  Pregnancies do occur with IUD users, as they are not perfect with use in real life.  The evidence is overwhelming, however, that they work by preventing fertilization, not by killing a fertilized egg.

Myth number two.  IUDs cause infections in your uterus.  This modern myth gained a lot of traction because it used to be true.  There's a long and rich history of studies showing that the insertion of an IUD is associated with a significantly increased risk of a pelvic infection.  

Almost all of these studies showed a really high rate of infection in the month following the placement of the device, and then a decrease in its incidence over time.  The concerns culminated in the United States with the furor over the Dalkon Shield.  These IUDs had a tail made of filaments encased in plastic that aided in its removal.  Unfortunately, this plastic was found to crack over time inside the woman's vagina or uterus, exposing the filaments to the rest of the world.  Bacteria could colonize in the filaments, which then climbed up into the pelvic area, causing an infection.

They don't make them like that anymore.  When it comes to new IUDs, we don't have the same worries.  More modern devices and studies in more recent years don't appear to show these same rates of infection.  They are sometimes higher than we'd like to see sometimes, but not nearly as high as in the past, but even those slight differences have been called into question.  

This is partly a fault with how some of the studies themselves were designed and conducted.  Many of them were done in other countries, in ways which make them difficult to generalize to the United States and some other developed nations.  

But a larger concern is what the IUD is being compared to.  You see, some contraceptives, like condoms or ointments, can actively work to reduce the rates of pelvic infections.  So when you compare the IUD, which does not prevent infections, to those things, the IUD looks much worse.  

But this doesn't mean that the IUD is causing infections, it's just that the IUD doesn't prevent them.  A better designed study would compare the IUD to no contraception at all.  When you put all this together, it appears that the rates of infection in IUD users today don't seem to be much different from those of sexually active women who don't use them.  In other words, they don't cause infections. 

Myth number three.  You are not going to be able to have children later if you use an IUD.  Almost no debate about the use of IUDs is as heated as this one, and it stems from two papers that appeared in the New England Journal of Medicine in the mid 1980s.  Both of them concerned women who had never been pregnant before.  

The first found that compared to women who had never used an IUD, a woman who had ever used one had a 260 percent chance of developing primary tubal infertility.  The second study found similar results, especially for the Dalkon Shield, which increased the risk 330% over having never used an IUD.  However, even in those studies, women who had used the IUD with only a single partner saw no increased risk of infertility.  

After these studies were published, IUD use fell off sharply in young women who had never been pregnant.  But research that followed, began to contradict the earlier findings.  A study out of Norway in 1988, showed that 100% of the women in the study were able to get pregnant within thirty-nine months of stopping IUD use.  

Some people theorize that perhaps women who had their IUDs removed because of complications would be more likely to develop infertility.  The Norway study didn't include such women, so a study came out of New Zealand, following up data on more than 1050 women who had used and then had IUDs removed for any reason, and then looked at this question.  They found that there were no significant reductions in fertility comparing women who had complications compared to those who didn't.  

These days the overwhelming evidence shows that the risk of significant pelvic infection from having multiple partners is the true cause of increased rates of infertility.  Monogomous women who use IUDs have no real risk for infertility at all.  This was made explicit in a 2001 study in Mexico, that proved that it's pelvic infections, and not IUD use, that is associated with infertility.  If you want to stay fertile, it's not the IUD you've got to worry about.  It's multiple sexual partners and not practicing safe sex.

Myth number four.  IUDs cause significant bleeding or pain.  One of the reasons women cite for not wanting to use IUDs is that they can cause significant bleeding or pain.  One study showed that about one in five women who used copper IUDs report heavy bleeding for the first three months.  But that seems to go away over time.  Another larger study found that menstrual flow increases in about 30% of copper IUD users, but that hemoglobin levels stabilized before a year of use. 

It's true that these complaints are cited by some women who choose to have their IUDs removed, but it's important to put this concern in context by comparing it to other forms of birth control.  It turns out that women that use IUDs are much more likely to continue using them than other forms of birth control.  A study in France found that women who use an IUD do so continuously for an average of 55 months.  Women who use the pill, though, do so continuously for only 43 months.  They use condoms continuously for 19 months, and spermicides continuously for 13 months.

So women who use IUDs use them for a relatively long time.  If these bleeding concerns were really so overwhelming, it's likely that more women would abandon the IUD as a method of birth control.  That doesn't happen.  Besides, some women who use the hormonal IUDs find that bleeding sometimes slows and even sometimes stops.  A number of the women I know consider that to be a feature, not a bug.

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