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By Rebecca H. Allen, MD, MPH
Assistant Professor, Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Providence, RI
Dr. Allen reports no financial relationships relevant to this field of study.
Synopsis: In this prospective cohort study, women who used the copper IUD for emergency contraception had lower unintended pregnancy rates in the following 12 months compared to women who chose the oral levonorgestrel pill.
Source: Turok DK, et al. Emergency contraception with a copper IUD or oral levonorgestrel: An observational study of 1-year pregnancy rates. Contraception 2014;89:222-228.
The authors conducted a prospective cohort study comparing the copper T380A intrauterine device (IUD) and oral levonorgestrel (1.5 mg LNG) for emergency contraception (EC) among 542 women at two family planning clinics in Salt Lake City, Utah, between November 2009 and July 2010. Participants were aged 18-30 years, had unprotected intercourse within 120 hours of presenting, and chose the method they desired free of charge. Exclusion criteria were uterine infection within 3 months and gonorrhea or chlamydia infection in the past 60 days. IUDs were placed by nurse practitioners who were experienced providers. Women were followed with phone calls at 1, 3, 6, 9, and 12 months to determine pregnancy rates. The primary outcome was the rate of unplanned pregnancy in the 12 months after presenting for EC.
Of the 542 women studied, 215 (40%) chose the IUD and 327 (60%) chose oral LNG. Women in the IUD group were slightly older (23.1 years vs 22.0 years; P < 0.001) and more likely to have heard of the IUD for contraception (94% vs 73%; P = 0.014). In both groups, approximately one-third of women were not using any method of contraception at the time of presentation (IUD group 35%, oral LNG group 42%) and a little more than half were nulliparous (IUD group 59%, oral LNG group 53%). In the IUD group, there were 42 insertion failures; therefore, 173 women actually received the device. There were four pregnancies (1%) in the oral LNG group from EC failure and none in the copper IUD group. The 12-month follow-up rate was overall 82% with no significant differences in each arm. Ninety-five women continued the IUD with only one pregnancy, there were 17 IUD expulsions with one pregnancy, and 37 IUD removals with subsequently seven pregnancies. In the oral LNG group, there were 40 pregnancies over the following 12 months. The risk of pregnancy in the IUD group at 12 months was less than half that of the oral LNG group (hazard ratio, 0.42; 95% confidence interval [CI], 0.20-0.85).
In the United States, approximately half of pregnancies are unintended and 40% of these end in abortion.1 EC is intended to reduce the risk of pregnancy after unprotected intercourse or method failure and can play an important role in reducing unintended pregnancies. While this has been demonstrated on an individual level, the population effect of EC on the national unintended pregnancy rate has been disappointing.2 This is likely due to the fact that women underestimate their risk of pregnancy and do not take EC as often as they should. The effectiveness of EC depends on the mechanism of action of the method and when the method is used after unprotected intercourse. Ideally, EC should work at various points in the menstrual cycle and for 5 days after unprotected intercourse, the lifespan of the sperm in the female reproductive tract. In addition, given that many women have repeated acts of unprotected intercourse in the same cycle, a method that provides ongoing contraception would be beneficial.3
Oral LNG (1.5 mg, Plan B OneStep, Teva Pharmaceuticals) is available over-the-counter in the United States and is effective up to 72 hours after intercourse. Ulipristal acetate (30 mg, Ella, HRA Pharma) is available by prescription and is effective up to 120 hours after intercourse.4 In one study, among women who took EC within 72 hours of unprotected intercourse, the pregnancy rate was 1.8% for ulipristal acetate (UPA) and 2.6% for LNG. When taken between 72-120 hours after unprotected intercourse, UPA prevented pregnancy more effectively than LNG (P = 0.037).5 Overall, the risk of pregnancy was reduced by half among women using UPA compared to LNG. The reason that UPA is superior to LNG is its greater effect preventing ovulation.6 Of note, breastfeeding should be avoided for 36 hours after using UPA.4
Risk factors for failure of oral EC are body weight, intercourse during the fertile time of the cycle, and repeated acts of unprotected intercourse in the same cycle.7 Preliminary data are concerning regarding the efficacy of oral EC in overweight and obese women. One study found that obese women have a three times greater risk of pregnancy following use of oral EC compared to normal weight women (odds ratio, 3.60; 95% CI, 1.96-6.53; P < 0.001).7 LNG performs worse than UPA in overweight and obese women, losing efficacy when body mass index (BMI) exceeds 26 kg/m2, while UPA appears to retain effectiveness up to a BMI of 34 kg/m2.3 Of course, the most effective method of EC is the copper T 380A IUD, which has failure rates of < 1 per 1000 and is not affected by body weight.4 In addition, as a long-acting reversible contraceptive, it has few contraindications and high continuation and satisfaction rates.
This study, while not perfect, attempted to estimate the unintended pregnancy rates of women who chose the copper IUD or oral LNG for EC. They found that, when offered, a significant proportion of women were willing to use the copper IUD for EC. While the failed insertion rate was higher than normal, the authors speculate that the women, not having anticipated IUD insertion that day, may have experienced more anxiety and pain with the insertion process causing providers to abort the procedure. It is not surprising that women who received the copper IUD reported fewer pregnancies at 1 year than those receiving a one-time dose of LNG, given that 64% of those who received an IUD retained it at 12 months. In my opinion, the main benefit of this study is to show that the copper IUD for EC was well received by the participants. To date, the copper IUD has not been as popular for EC as the oral methods for obvious reasons: cost, logistics, and access. However, given the evidence, providers should strive to offer the copper IUD to their patients who request EC and have timely appointments available for insertion. Research is currently underway evaluating the LNG IUD for EC, given that most women prefer the bleeding profile of the LNG IUD to that of the copper IUD. Hopefully, the LNG IUD will also prove effective for EC and we will have more options to offer women.