Effectiveness of IUDs: a review

Area of Science:

• Reproductive Health
• Contraception Research
• Medical Device Efficacy

Background:

• Intrauterine devices (IUDs) are a common form of long-acting reversible contraception.
• Historical data from large trials provide insights into IUD performance over time.

Purpose of the Study:

• To analyze the efficacy of various Intrauterine Devices (IUDs) based on large-scale, multicenter randomized trials.
• To identify factors influencing IUD failure rates, such as device type and participant demographics.

Main Methods:

• Analysis of data from over 50,000 woman-years of experience in randomized trials of IUDs conducted between 1970 and 1986.
• Comparison of pregnancy rates across different IUD types, including non-medicated, early copper, newer copper, and hormone-releasing devices.
• Evaluation of long-term (4-year) cumulative failure rates.

Main Results:

• Non-medicated IUDs and early copper IUDs (Copper 7, TCu 200) showed pregnancy rates above 2 per 100 woman-years.
• Five newer copper IUDs demonstrated significantly lower failure rates (<2 per 100 woman-years), with some below 1.
• Levonorgestrel-releasing IUDs (20 mcg/day) showed comparable effectiveness to the best copper IUDs, while higher doses (25 mcg/day) were less effective.
• Four-year cumulative pregnancy rates for advanced copper IUDs (TCu 220C, Nova T, TCu 380A, MLCu 375) were below 5 per 100 users.

Conclusions:

• The effectiveness of IUDs is significantly influenced by the specific device type and the age of the user, particularly the proportion of women under 25.
• Modern copper IUDs represent a substantial improvement in efficacy over older IUD models and some hormone-releasing systems.
• Specific advanced copper IUDs and a 20 mcg/day levonorgestrel IUD offer highly effective, long-term contraception with low pregnancy rates.