ObjectivesTo estimate the hazard of incident idiopathic intracranial hypertension, a potentially blinding condition, among women using levonorgestrel intrauterine devices (LNG-IUD) compared to copper IUD, as conflicting associations have been reported. Study designThis retrospective, longitudinal cohort study identified women ages 18–45 years in a large care network (January 1, 2001, to December 31, 2015) using LNG-IUD, subcutaneous etonogestrel implant, copper IUD, tubal device/surgery, or hysterectomy. Incident idiopathic intracranial hypertension was defined as the first diagnosis code for after 1 year without any codes and following brain imaging or lumbar puncture. Kaplan-Meier analysis estimated time-dependent probabilities of idiopathic intracranial hypertension at 1 and 5 years after incident contraception use, stratified by type. Cox regression estimated the hazard of idiopathic intracranial hypertension associated with LNG-IUD use compared to copper IUD (primary comparison) after adjusting for sociodemographics and factors associated with idiopathic intracranial hypertension (e.g., obesity) or contraception selection. A sensitivity analysis with propensity score-adjusted models was performed. ResultsOf 268,280 women, 78,175 (29%) used LNG-IUD, 8715 (3%) etonogestrel implant, 20,275 (8%) copper IUD, 108,216 (40%) hysterectomy, 52,899 (20%) tubal device/surgery, and 208 (0.08%) developed idiopathic intracranial hypertension over a mean follow-up of 2.4 ± 2.4 years. Also, 1-/5-year Kaplan-Meier idiopathic intracranial hypertension probabilities were 0.0004/0.0021 for LNG-IUD and 0.0005/0.0006 for copper IUD users. LNG-IUD use did not show significantly different hazard of idiopathic intracranial hypertension compared to copper IUD (adjusted hazard ratio 1.84 [95% CI 0.88, 3.85]). Sensitivity analyses were similar. ConclusionsWe did not observe a significantly increased hazard of idiopathic intracranial hypertension among women using LNG-IUD compared to copper IUDs. ImplicationsThe lack of an association between LNG-IUD use and idiopathic intracranial hypertension in this large observational study provides reassurance to women considering initiation or continued use of this highly effective contraceptive method.