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What Are Intrauterine Devices for Birth Control?

An intrauterine device (IUD) is a method of contraception that requires the placement of a small, T-shaped device inside the uterus. Contraception refers to precautionary measures to prevent vaginal intercourse from resulting in pregnancy.

Intrauterine devices are one of the most effective methods of contraception. IUDs are useful for long term contraception because they last for several years, some even up to 12 years.

How do intrauterine devices work?

Intrauterine devices primarily work by preventing the fertilization of the egg and its implantation in the uterus. The presence of the foreign object makes the uterine environment hostile for sperm and fetal implantation.

Some IUDs also release measured doses of hormones which work by:

  • Thinning the uterus lining (endometrium) to prevent implantation
  • Thickening the cervical mucus to prevent sperm passage

What are the types of intrauterine devices?

Copper T380

Copper T380 is a T-shaped polyethylene device wrapped with fine copper wire around the vertical stem. Copper T380 contains 380 mg of copper in its stem and arms. The device elicits a foreign body reaction in the uterus, which makes it impossible for sperm to survive or fertilization to take place. A Copper T380 implant can remain effective for 12 years.

  • Copper T380 is also the most effective emergency contraception method for use after unprotected vaginal intercourse or known/suspected contraceptive failure.
  • Copper T380 can be inserted up to seven days after unprotected intercourse to reduce the risk of pregnancy by more than 99%.

Levonorgestrel intrauterine system (LNG-IUS)

The levonorgestrel intrauterine system is also a polyethylene T-shaped device which releases in measured doses the hormone levonorgestrel, a form of progesterone. Levonorgestrel thickens the consistency of the cervical mucus, inhibiting sperm mobility. Levonorgestrel also suppresses the endometrial growth and prevents implantation.

There are several LNG-IUS devices available, and each device releases a different volume of hormone per day. The dosage declines over a few years.

Following are the LNG-IUS devices approved by FDA:

  • Mirena: for seven years
  • Liletta: for five years
  • Skyla: for three years
  • Kyleena: for three years.

Efficacy: The failure rate is 0.6% with Copper T380 and 0.1% with LNG-IUS.



  • Risk of uterine perforation during insertion
  • Increase in blood loss and menstrual cramps in the first few cycles with Copper T380
  • No protection against sexually transmitted diseases (STDs)
  • Cannot be used in women with
    • Abnormal uterine cavity
    • Undiagnosed genital bleeding
    • Uterine or cervical malignancy
    • Wilson disease (excessive copper deposits in the body)
    • Known or suspected pregnancy
    • Cervical or endometrial infections

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