UC Davis

Objective

Assess the relationship between parity and prior route of delivery to levonorgestrel 52 mg intrauterine system (IUS) expulsion during the first 72 months of use.

Study design

We evaluated women enrolled in the ACCESS IUS multicenter, Phase 3, open-label clinical trial of the Liletta levonorgestrel 52 mg IUS. Investigators evaluated IUS presence at 3 and 6 months after placement and then every 6 months and during unscheduled visits. We included women with successful placement and at least one follow-up assessment. We evaluated expulsion rates based on obstetric history; for prior delivery method subanalyses, we excluded 12 participants with missing delivery data. We determined predictors of expulsion using multivariable regression analyses.

Results

Of 1714 women with IUS placement, 1710 had at least one follow-up assessment. The total population included 986 (57.7%) nulliparous women. Sixty-five (3.8%) women experienced expulsion within 72 months, 50 (76.9%) within the first 12 months. Expulsion rates among nulliparous women (22/986 [2.2%]) or parous women with any pregnancy ending with a Cesarean delivery (6/195 [3.1%]) differed from parous women who only experienced vaginal deliveries (37/517 [7.2%]) (p < 0.001). In multivariable regression, obesity (adjusted odds ratio [aOR] 2.2, 95% confidence interval [CI] 1.3-3.7), parity (aOR 2.2, 95% CI 1.2-4.1), and non-white race (aOR 1.8, 95% CI 1.1-3.2) predicted expulsion. Among parous women, obesity (aOR 2.2, 95% CI 1.2-4.2) increased the odds and having ever had a cesarean delivery (aOR 0.4, 95% CI 0.1-0.9) decreased the odds of expulsion.

Conclusion

IUS expulsion occurs in less than 4% of users over the first 6 years of use and occurs mostly during the first year. Expulsion is more likely among obese and parous women.

Implications

Levonorgestrel 52 mg intrauterine system expulsion occured more commonly in parous than nulliparous women; the increase in parous women is primarily in women who had vaginal deliveries only. The association between obesity, delivery route, and IUS expulsion needs further elucidation.