Abstract
OBJECTIVE: This study aimed to investigate whether the use of levonorgestrel intrauterine devices (LNG-IUD) is associated with an increased need for medically assisted reproductive (MAR) treatment compared to other contraceptive methods. METHODS: This register-based historical cohort study included 733 875 Danish women aged 18-42 years between 2000 and 2018. The primary outcome was initiation of MAR treatment in the public healthcare sector. The exposure was categorized as the use of either LNG-IUD, copper (Cu)-IUD, progesterone-only pills (POPs) or combined oral contraceptive pills (OCPs) during the study period. Cox proportional hazard regression was used to assess the risk of initiation of MAR treatment after LNG-IUD use relative to other contraceptive methods. RESULTS: Adjusted analysis revealed that POPs and OCPs were associated with increased hazards of MAR treatment relative to LNG-IUD with hazard ratios (HR) of 2.91 (95% confidence interval (CI): 1.81-4.68, P < 0.001) and 6.58 (95% CI: 4.32-10.02, P < 0.001), respectively, while no difference was observed for Cu-IUD relative to LNG-IUD (HR 1.17, 95% CI: 0.61-2.25, P = 0.644). CONCLUSION: Use of LNG-IUD was not associated with an increased need to undergo MAR treatment compared to Cu-IUD, POPs and OCPs. However, due to limitations of the current study more research is needed in order to determine whether the use of LNG-IUD has a negative effect on female fertility.