|Found here. IUDs are back in style.|
Neon sunglasses? Not so much.
The modern incarnation of the IUD is possibly safer and more effective than oral contraception. Chances of pregnancy on the IUD range from 0-1.1 per 100 woman-years of use, and they get lower with each year you use it (Prager and Darney 2007). That is far better than your chances on the pill.
The IUD suffers from a bad reputation, in part due to misinformation or misunderstanding on the part of medical providers. Harper et al (2008) surveyed 816 physicians, nurse practitioners and physician assistants who each serve more than 100 contraceptive patients per year in the California State family planning program. They found that 40% of medical providers didn’t offer IUDs to patients, 36% provided infrequent counseling. Further, 46% thought nulliparous women, and 39% thought postabortion women were good candidates for the IUDs. Younger physicians were more likely than older physicians to recommend the IUD (Harper et al. 2008), which suggests a generational gap due to the overinflated descriptions of the dangers of early IUDs.
So let’s go through the actual pros and cons of this form of contraception, so that over the course of the summer you can compare this information to what you’ll be learning about the pill.
Remember, I’m just an anthropologist who studies this stuff. I am not a medical doctor.
Danger danger! Or not
The biggest danger from an IUD is that it could perforate the uterus, or be expelled from it. And that can certainly be painful, reduce fertility, or get you pregnant when you think you are protected. So let’s look at how often this happens.
Prager and Darney (2007) wrote a review on the levonorgestrel IUD (hormone-releasing, like Mirena) in nulliparous (that means no parity, or no children) women. This is important because many still carry the misconception that nulliparous women shouldn’t use IUDs, because of an increased risk of perforation, infertility, pelvic inflammatory disease risk, and difficulty in placement.
There are notable differences between the parous (has had children) and nulliparous (no kids) uterus. The parous uterus is a little bigger, and the cervix dilates a bit more easily. However, it turns out that for the most part these differences are not great enough to produce any differences in side effects or danger to the woman using it.
Prager and Darney (2007) found six studies on perforation or expulsion rates for IUDs (some copper, some hormone-releasing, which are made of plastic and are flexible). They did not find enough data to support a link either way for nulliparity and perforation, because the studies they found had anywhere from zero to two nulliparous women in them. That said, the perforation rates for each study ranged from 0-1.3% in one study, and 2.6 out of 1000 in another (Prager and Darney 2007).
Expulsion rates do not seem to differ between parous and nulliparous women, and again, are very low for all women. The annual expulsion rate among cited studies was 0-4.2 per 100, 0-1.2% per year, and 0-0.2% per year (Prager and Darney 2007). The one important point they do make is that there is a very slightly increased risk of expulsion for lactating women – perhaps this is due to the oxytocin released during nipple stimulation, which could contract muscle?
The other concern sometimes mentioned is that of pelvic inflammatory disease. PID is an infection of the uterus and is usually associated with a sexually transmitted disease. PID can increase the risk of infertility. So for women who haven’t had a kid, but want to some day, the concern about getting PID can loom large.
However, Prager and Darney (2007) surveyed the literature and found that the only studies that support a link between PID and IUDs involves an IUD no longer on the market, or was associated with high-risk sexual behavior.
In some women, copper IUDs can increase menstruation. However, the hormone-releasing IUDs tend to decrease menstruation, and many women stop getting periods altogether. Hormone-releasing IUDs can be prescribed to women with menorrhagia, or pathologically heavy menstruation, too.
Prager and Darney (2007) describe a study in which hormone-releasing IUD users were compared to oral contraceptive users. These IUD users had less dysmenorrhea (painful periods), less spotting, fewer days of bleeding, fewer cycles. Further, 88% of the IUD users wanted to continue with that method of contraception after a year, compared to 68% of pill users, and this difference was statistically significant (p = 0.003).
Romer and Linsberger (2009) also looked at satisfaction with the hormone-releasing IUD in a sample of 8680 women across 18 countries: 95% were satisfied with their method of contraception.
The fine print
Insertion of the IUD can be a little more painful in a nulliparous woman, since her cervix has not dilated before. Also, a minority of women may spot for a while after insertion of the IUD... and by a while, I mean a few months. But once those few months of light spotting are over, they often don’t get a period again until removing the IUD. And of course, the IUD is not conducive to sudden desires to start the babymaking process: you will need to schedule its removal first.
However, with the number of women who are ambivalent at best about birth control pills, but do not want to use a barrier method, the IUD offers a lot in the way of safety, efficacy and ease of use.
Harper CC, Blum M, de Bocanegra HT, Darney PD, Speidel JJ, Policar M, & Drey EA (2008). Challenges in translating evidence to practice: the provision of intrauterine contraception. Obstetrics and gynecology, 111 (6), 1359-69 PMID: 18515520
Prager, S., & Darney, P. (2007). The levonorgestrel intrauterine system in nulliparous women Contraception, 75 (6) DOI: 10.1016/j.contraception.2007.01.018
Römer, T., & Linsberger, D. (2009). User satisfaction with a levonorgestrel-releasing intrauterine system (LNG-IUS): Data from an international survey The European Journal of Contraception and Reproductive Health Care, 14 (6), 391-398 DOI: 10.3109/13625180903203154