Levonorgestrel intrauterine contraceptive systems (13.5 mg and 52 mg) and risk of ectopic pregnancy.

The absolute risk of ectopic pregnancy during the use of LNG-IUS remains low. Our method may underestimate as well as overestimate the Pearl index for ectopic pregnancy. The findings underline the importance of identifying risk factors for ectopic pregnancy at insertion, and to rule out ectopic pregnancy for all women presenting with abdominal discomfort during the use of LNG-IUS. Longer observation periods and prospective studies in a general population are a priority for further research.