Efficacy of medication abortion with concurrent initiation of progestin contraceptives: A retrospective cohort study

Objectives: To evaluate medication abortion (MAB) outcomes for participants receiving intramuscular depot medroxyprogesterone acetate (DMPA) injections or subdermal etonogestrel implants concurrently with mifepristone compared to those who did not in a real-world setting. Study design: This retrospective cohort study included MAB patients from one Planned Parenthood health center in St. Paul, MN, between 2017 and 2019. We abstracted electronic health records and compared sociodemographic variables, clinical information, and treatment failure rates (primary outcome) between study groups with logistic regression (generating odds ratios [OR] and 95% confidence intervals [CI]). Results: Among 7296 MAB participants, 224 (3.1%) received DMPA injections and 309 (4.2%) received etonogestrel implants concurrently with mifepristone; 141 (62.9%) and 200 (64.7%) completed follow-up respectively. From a random sample of 1000, 990 comparison participants met inclusion criteria; 704 (71.1%) completed follow-up. Fourteen (9.9%) DMPA participants (aOR 4.26, 95% CI 1.87–9.68, p < 0.001) and 6 (3.0%) etonogestrel implant participants (aOR 1.38, 95% CI 0.48–3.55, p = 0.522) required additional treatment to empty the uterus and/or had an ongoing pregnancy, each contrasted with 15 (2.1%) comparison patients (models adjusted for gestational duration, patient age, parity, and race). Conclusion: Although our study is limited by high rates of loss to follow-up, our analysis suggests that concurrent administration of DMPA with mifepristone may decrease MAB efficacy, while etonogestrel implant placement does not appear to alter MAB outcomes. These findings are overall consistent with prior literature and inform post-MAB contraception counseling. Implications: This retrospective cohort study reinforces prior randomized controlled trial findings that concurrent depot medroxyprogesterone acetate injection with mifepristone administration may decrease medication abortion efficacy. Conversely, concurrent etonogestrel contraceptive implant placement with mifepristone administration does not appear to decrease medication abortion efficacy. These findings inform post-abortion contraception counseling.