OBJECTIVES: To evaluate the association of postpartum timing of intrauterine device (IUD) insertion with risk of uterine perforation.
METHODS: APEX IUD was a retrospective cohort study conducted within four health care systems with access to electronic health records--three Kaiser Permanente sites (Northern California, Southern California, Washington) and Regenstrief Institute (Indiana). The study included data from 326,658 women (aged ≤50 years) with an IUD inserted during the study period. Date of delivery, IUD insertion, perforation diagnosis, and potential confounders were identified using structured and unstructured data. Perforation was defined as complete (IUD in pelvis or abdomen) or partial (embedded in myometrium). We calculated postpartum timing of IUD insertion and categorized it into discrete time periods: (1) 0-3 days, (2) 4 days to ≤6 weeks, (3) >6 to ≤14 weeks, (4) >14 to ≤52 weeks, and (5) >52 weeks or with no evidence of delivery. We estimated incidence rates and adjusted hazard ratios, using propensity scores to adjust for confounding.
RESULTS: Incidence [95% confidence interval (CI)] of uterine perforation per 1,000 person-years of follow-up by time period were: (1) 2.37 [1.18-4.24], (2) 5.53 [4.75-6.40], (3) 3.77 [3.42-4.15], (4) 2.24 [1.80-2.75], and (5) 0.68 [0.61-0.76]. Adjusted hazard ratios [95% CI], comparing groups 1 through 4 with group 5 were: (1) 2.73 [1.33-5.63], (2) 6.71 [4.80-9.38], (3) 4.64 [3.48-6.18], and (4) 2.93 [2.15-4.00].
CONCLUSIONS: Risk of uterine perforation is low overall. Postpartum IUD insertion risk varies by timing, with immediate and beyond 14 weeks appearing to have the lowest risk.
