Does the Levonorgestrel Content of an IUD Affect Risk for Ectopic Pregnancy?

Levonorgestrel-containing intrauterine devices (IUDs) are some of the most effective contraceptive options, with failure rates of <1% per year (U.S. Selected Practice Recommendations for Contraceptive Use; 2016). If pregnancy does occur with an IUD, risk for ectopic pregnancy is considerable. However, whether this risk varies based on an IUD's levonorgestrel content is uncertain.

Researchers evaluated risk for ectopic pregnancy among 1 million women in a Danish population-based registry. During 20 years, nearly 3000 ectopic pregnancies occurred. Risks for ectopic pregnancy were 7.7, 7.1, and 15.7 per 10,000 person-years with the 52-mg, 19.5-mg, and 13.5-mg levonorgestrel IUDs, respectively. Rates of ectopic pregnancy increased with duration …