Mirena Intrauterine System Timing of Insertion: A Randomized Controlled Trial (MISTIC)

In order to determine the timing of LNG-IUS insertion that results in a greater proportion of women using the LNG-IUS at 6-months post-partum, we will perform a randomized control trial of interval versus immediate post-placenta insertion. Women will be enrolled at 36-weeks gestation and greater. At the time of vaginal delivery, women will be randomized to receive either immediate post-placenta insertion of the LNG-IUS or routine insertion at 4-8 weeks post-partum. All patients will return at 4-6 weeks post-insertion and 6 months post-partum to confirm correct position of the LNG-IUS. The primary outcome of this sub-study is the number of LNG-IUS in the correct position at 6-months. Secondary outcomes include assessing the safety of post-placental LNG-IUS insertion and difference in acceptability and symptoms experienced by participants. This is a sub-study of the Contraceptive Choice Project, a prospective cohort study that aims to improve the use of long-acting contraception by removing financial barriers which has already enrolled over 5,000 patients. Association of this study with CHOICE offers unique advantages including infrastructure to support subject recruitment, retention and completion of follow-up as well as covering the cost of LNG-IUS devices.

We hypothesize that, despite higher expulsion rates, women randomized to receive the LNG-IUS immediately after placenta delivery will have higher rates of LNG-IUS continuation due to poor rates of follow up in the interval insertion group. This is likely to be particularly noticeable in our patient population, which is largely uninsured with poor access to healthcare. Further, typical symptoms of LNG-IUS insertion include bleeding and cramping, which may be disguised by the post-partum period. Published reports of immediate post-placenta insertion focus on expulsion rates and do not report on symptoms and satisfaction rates.