Higher dose levonorgestrel-releasing intrauterine systems lowers risk of ectopic pregnancy

Sweden: In a new study conducted by Karin Elgemark, it was found that when using levonorgestrel-releasing intrauterine systems (LNG-IUS) at any dosage, the risk of an ectopic pregnancy was minimal. The findings of this study were published in Obstetrics and Gynecology.

"A lower dose of hormones from LNG-IUS is associatied with a higher risk of ectopic pregnancy," and should be considered when counseling women with known risk factors" the researchers wrote in their study. 

With hormonal reservoirs of 13.5 mg, 19.5 mg, or 52 mg, this research sought to evaluate the Pearl Index for ectopic pregnancy risk in women using levonorgestrel-releasing intrauterine devices. The electronic medical record system was used to find women in Stockholm County, Sweden, who had been diagnosed with an ectopic pregnancy between January 1, 2014, and December 31, 2019. 2,252 ectopic pregnancy instances were included in the analysis's final results. Age, reproductive history, medical history, and current contraceptive usage were all collected.

The incidence rate of ectopic pregnancy during usage per 100 woman-years was calculated using the time of intrauterine device (IUD) installation prior to ectopic pregnancy and the quantity of LNG-IUS marketed throughout the research period (Pearl Index).

The key findings of this study were as follow:

1. There were 105 women with an ectopic pregnancy diagnosis who had a known kind of hormonal IUD in place; 94 of these women were taken into account in the Pearl Index calculations.

2. For the LNG-IUS 13.5-mg, the estimated Pearl Index for ectopic pregnancy was 0.136; for the LNG-IUS 19.5-mg, 0.037; and for the LNG-IUS 52-mg, 0.009.

3. The relative risk (RR) for ectopic pregnancy was greater for LNG 13.5 mg during the first year and for both 13.5 mg and 19.5 mg during the whole trial period, using the 52 mg LNG-IUS as the referent.

In conclusion, the findings indicate that the likelihood of an ectopic pregnancy increases with decreasing IUD dosage. When giving contraceptive advice to a woman with established risk factors for ectopic pregnancy who is thinking about a hormonal IUD, higher-dose LNG-IUS should be taken into account.

Reference:

Elgemark, K., Graner, S., McTaggart, J., Ramirez Löfström, J., Sörensen, D., Envall, N., & Kopp Kallner, H. (2022). The 13.5-mg, 19.5-mg, and 52-mg Levonorgestrel-Releasing Intrauterine Systems and Risk of Ectopic Pregnancy. In Obstetrics & Gynecology (Vol. 140, Issue 2, pp. 227–233). Ovid Technologies (Wolters Kluwer Health). https://doi.org/10.1097/aog.0000000000004846