What are the different types of progesterone Intrauterine Devices (IUDs)?

Types of Progesterone Intrauterine Devices (IUDs)

There are three main types of progesterone-releasing IUDs available in the United States: the 52-mg levonorgestrel IUD (Mirena), the 13.5-mg levonorgestrel IUD (Skyla), and the 52-mg levonorgestrel IUD (Liletta), each with different durations of effectiveness and specific characteristics. 1

Available Progesterone IUD Options

52-mg Levonorgestrel IUD (Mirena)

• Initially FDA-approved for 5 years of use
• Research now supports effectiveness for up to 7-8 years 1, 2
• Releases approximately 20 mcg of levonorgestrel daily
• Highest hormone dose among available progesterone IUDs
• Most effective at reducing menstrual bleeding 3
• Ideal for women with heavy menstrual bleeding

13.5-mg Levonorgestrel IUD (Skyla)

• FDA-approved for 3 years of use 1, 4
• Lower hormone dose than Mirena
• Slightly smaller in size than Mirena
• May be preferred for nulliparous women or those with smaller uterine cavities

52-mg Levonorgestrel IUD (Liletta)

• Initially FDA-approved for 3 years of use 1
• Similar hormone dose to Mirena
• Comparable effectiveness to Mirena

Mechanism of Action

All progesterone IUDs work through multiple mechanisms:

• Thickening of cervical mucus to prevent sperm entry
• Inhibiting sperm motility
• Creating an unfavorable endometrial environment for implantation
• Primary mechanism is preventing fertilization 4

Effectiveness and Benefits

• All progesterone IUDs have failure rates less than 1%, making them highly effective contraceptives 4, 1
• Rapid return to fertility after removal 4, 1
• Significant reduction in menstrual bleeding (up to 90% reduction with Mirena) 5, 3
• Improvement in dysmenorrhea (menstrual pain) 5
• Can be used for non-contraceptive benefits such as treatment of heavy menstrual bleeding 6, 3
• Can provide endometrial protection for perimenopausal and postmenopausal women on estrogen replacement therapy 6

Side Effects and Considerations

• Most common side effect is irregular bleeding or spotting during the first few months after insertion 4
• After initial adjustment period, many women experience lighter periods or amenorrhea 2
• Expulsion rates may be slightly higher in younger, nulliparous women (up to 5%) 4
• Insertion may cause moderate to severe pain, particularly in nulliparous women 4
• Contraindications include current purulent cervicitis, active gonorrhea or chlamydia infection, current PID, pregnancy, and uterine anomalies that distort the cavity 4, 1

Comparison with Copper IUD

While not a progesterone IUD, it's important to note that the Copper T380-A (ParaGard) is another long-acting IUD option:

• Contains no hormones
• FDA-approved for 10 years (effective for up to 12 years) 1
• May increase menstrual bleeding (unlike progesterone IUDs which decrease it) 1
• Can be used as emergency contraception within 5 days of unprotected intercourse 4

Clinical Decision Making

When selecting a progesterone IUD, consider:

1. Desired duration of use (3 years for Skyla vs. 5+ years for Mirena/Liletta)
2. Need for menstrual blood loss reduction (Mirena offers greatest reduction)
3. Uterine size (Skyla may be better for smaller uterine cavities)
4. History of heavy menstrual bleeding (Mirena preferred)
5. Need for non-contraceptive benefits (Mirena has more approved non-contraceptive indications)

The progesterone IUD selection should be based on these factors, with Mirena generally offering the most versatile option with the longest duration and strongest evidence for both contraceptive and non-contraceptive benefits.