The Effect of Age, Parity and Body Mass Index on the Efficacy, Safety, Placement and User Satisfaction Associated With Two Low-Dose Levonorgestrel Intrauterine Contraceptive Systems: Subgroup Analyses of Data From a Phase III Trial

PLoS One. 2015 Sep 17;10(9):e0135309. doi: 10.1371/journal.pone.0135309. eCollection 2015.


Objective: Two low-dose levonorgestrel intrauterine contraceptive systems (LNG-IUSs; total content 13.5 mg [average approx. 8 μg/24 hours over the first year; LNG-IUS 8] and total content 19.5 mg [average approx. 13 μg/24 hours over the first year; LNG-IUS 13]) have previously been shown to be highly effective (3-year Pearl Indices: 0.33 and 0.31, respectively), safe and well tolerated. The present subgroup analyses evaluated whether or not outcomes were affected by parity, age (18-25 vs 26-35 years), or body mass index (BMI, <30 vs ≥30 kg/m2).

Methods: Nulliparous and parous women aged 18‒35 years with regular menstrual cycles (21‒35 days) requesting contraception were randomized to 3 years of LNG-IUS 8 or LNG-IUS 13 use.

Results: In the LNG-IUS 8 and LNG-IUS 13 groups, 1432 and 1452 women, respectively, had a placement attempted and were included in the full analysis set; 39.2%, 39.2% and 17.1% were 18-25 years old, nulliparous and had a BMI ≥30 kg/m2, respectively. Both systems were similarly effective regardless of age, parity or BMI; the subgroup Pearl Indices had widely overlapping 95% confidence intervals. Placement of LNG-IUS 8 and LNG-IUS 13 was easier (p < 0.0001) and less painful (p < 0.0001) in women who had delivered vaginally than in women who had not. The complete/partial expulsion rate was 2.2-4.2% across all age and parity subgroups and higher in parous than in nulliparous women (p = 0.004). The incidence of pelvic inflammatory disease was 0.1-0.6% across all age and parity subgroups: nulliparous and younger women were not at higher risk than parous and older women, respectively. The ectopic pregnancy rate was 0.3-0.4% across all age and parity subgroups. Across all age and parity subgroups, the 3-year completion rate was 50.9-61.3% for LNG-IUS 8 and 57.9-61.1% for LNG-IUS 13, and was higher (p = 0.0001) among older than younger women in the LNG-IUS 8 group only.

Conclusions: LNG-IUS 8 and LNG-IUS 13 were highly effective, safe and well tolerated regardless of age or parity.

Trial registration: Clinical NCT00528112.

Publication types

  • Clinical Trial, Phase III
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Body Mass Index*
  • Consumer Behavior / statistics & numerical data*
  • Contraceptive Agents, Female / administration & dosage
  • Contraceptive Agents, Female / adverse effects
  • Contraceptive Agents, Female / pharmacology
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Intrauterine Devices, Medicated / adverse effects*
  • Intrauterine Devices, Medicated / statistics & numerical data
  • Levonorgestrel / administration & dosage
  • Levonorgestrel / adverse effects*
  • Levonorgestrel / pharmacology*
  • Pain / etiology
  • Parity*
  • Pregnancy
  • Safety*
  • Young Adult


  • Contraceptive Agents, Female
  • Levonorgestrel

Associated data


Grant support

The study was funded by Bayer HealthCare Pharmaceuticals. The authors also acknowledge medical writing support in the development of the manuscript, provided by Chameleon Communications, with the financial support of Bayer HealthCare. The authors Thomas Schmelter, Sarah Rybowski and Kimberly Rosen are employees of Bayer HealthCare. Kimberly Rosen was involved in the design of the study and verified the data included in the manuscript, Thomas Schmelter was the study statistician and Sarah Rybowski verified the data included in the manuscript. In addition, they all contributed to the writing of the manuscript.