Sixty thousand woman-years of experience on the levonorgestrel intrauterine system: an epidemiological survey in Finland.

Objective: An epidemiological survey was carried out in Finland to establish the performance of the levonorgestrel intrauterine system (LNG-IUS) in a large population of women regularly using the system for contraception.

Study Design: All women who had LNG-IUS inserted between 1990 and 1993 were sent a questionnaire with questions about general health status, reproductive and contraceptive history and gynecological problems and a set of questions about their experience on the LNG-IUS.

Results: The women who had a LNG-IUS inserted between April 1990 and December 1993 were asked to participate in an epidemiological survey. At the insertion visit, the women were asked to fill in a questionnaire, to consent to further use of the information by signing their initials and to return the questionnaire to the manufacturer. The number of returned forms was 23,885. The names and addresses of these women were acquired from the National Register and a questionnaire with 75 questions was sent to them. Of the questionnaires, 75% were returned. Experience covered 58,600 woman-years. The mean age of the users of the LNG-IUS was 40 years. Most of them (99.3%) were parous, most often with two or three children. The cumulative 5-year Pearl index was 0.18 and there were 108 pregnancies in the study population during the use of the LNG-IUS. The continuation rates for 1, 2, 3, 4 and 5 years were 0.94, 0.87, 0.82, 0.76 and 0.65, respectively. Removal before the full 5 years was most common among the youngest age group. Bleeding disorders, infections and pain during LNG-IUS use were associated with the highest risk for discontinuation. The risk of premature removal was markedly diminished among women with totally or occasionally missed periods.

Conclusions: The response rate to the survey was high and the sample studied was exceptionally large. The continuation rate of LNG-IUS was high up to 5 years. The symptoms associated with premature removal agreed with results from earlier randomized studies of the LNG-IUS.