EXPULSION RISK FACTORS FOR A LOW-DOSE COPPER IUD

Abstract

Objectives

This analysis evaluates expulsion rates among participants in a phase 3 study of a novel, low-dose copper (Cu 175mm²) intrauterine device (IUD) with a flexible nitinol frame.

Methods

In this prospective, single-arm, open-label study, participants at risk for pregnancy aged 17-45 received a Cu 175mm² IUD and were followed for three years. This secondary analysis evaluates expulsion rates for all enrolled participants with successful device placement and used logistic regression to assess expulsion risk by parity, menstrual cup use (any time during study), BMI category, breastfeeding status, postpartum status (birth within one year prior to enrollment), and age.

Results

Of 1,601 participants who had the device successfully placed, 960 (60.0%) were nulliparous; 151 (9.4%) used menstrual cups; 510 (31.9%) had a BMI ≥30.0 kg/m²; 33 (2.1%) reported breastfeeding at the time of placement; and 127 (7.9%) were within one year postpartum. Participants’ mean (SD) age was 27.6 (5.8) years. Overall, 36 (2.2%) participants experienced device expulsion in year 1 and 63 (3.9%) over three years. Over three years, the Kaplan-Meier cumulative incidence of expulsion for menstrual cup users vs. non-menstrual-cup users was 0.11 (95% CI, 0.07-0.17) vs. 0.05 (95% CI, 0.03-0.06). Cumulative expulsion did not vary significantly based on parity, BMI category, breastfeeding status, or postpartum status. Logistic regression only associated menstrual cup use with IUD expulsion over three years (OR, 4.0; p<0.0001).

Conclusions

After three years of follow-up, novel Cu 175mm² IUD users experienced a low rate of expulsion with only menstrual cup use associated with a significantly increased risk for IUD expulsion.