To assess the contraceptive performance of the 52-mg 20 μg/day levonorgestrel-releasing
intrauterine system (LNG-IUS, Mirena; Bayer Oy, Turku, Finland) among women who maintain
the same device without changes after 60 months.
This is a chart review study in which we assessed the charts of 766 women who continue
the same LNG-IUS for contraception beyond 60 months. The women were evaluated at the
Family Planning clinic, University of Campinas Medical School, Campinas, SP, Brazil,
from November 1990 to March 2011. We obtained sociodemographic data, duration of use,
continuation and discontinuation rates and reasons, bleeding pattern at the recorded
last visit. The statistical analysis was performed using Kaplan–Meier analysis.
A total of 776 charts were identified of women who used the LNG-IUS beyond 60 months.
The mean age (±S.E.M.) at LNG-IUS placement was 32.0±0.2 years (ranged 15 to 44 years;
median was 32 years). The distribution of number of pregnancies was 0–1 (45%); 2–4
(54.1%) and≥5 (0.9%). The median length of the LNG-IUS' use was 73 months after placement
(ranged 61–184 months). Zero pregnancies were reported and the main reasons for discontinuation
were expiration of approved effective lifespan, menopause and planning pregnancy.
The cumulative women-years (W-Y) of exposure were 967 and 1403 up to seven and 15
years, respectively. The main bleeding pattern reported by the women was amenorrhea.
The 52-mg 20 μg/day LNG-IUD (Mirena) showed continue contraceptive efficacy beyond
5 years of use with no pregnancies detected over 967 and 1403 W-Y up to seven and
15 years after placement.
The 52-mg 20 μg/day LNG-IUD presented a very high contraceptive efficacy beyond the
first 5 years of lifetime labeled. Increasing data support that efficacy beyond 5
years of use, and new data suggested efficacy as long as 15 years. Healthcare professionals,
policy makers and stakeholders could take advantage of the present information to
decide to maintain the same device at least up to seven years. Furthermore, amenorrhea
could be a good indicator of contraceptive effect.