Intrauterine Devices (IUDs) for Birth Control)
An intrauterine device (IUD) is a small T-shaped plastic device that is placed in the uterus to prevent pregnancy. A plastic string is attached to the end to ensure correct placement and for removal. IUDs are an easily reversible form of birth control, and they can be easily removed. However, an IUD should only be removed by a medical professional.
Currently in the United States, 2 types of IUDs are available: copper and hormonal. Approximately 2% of women who use birth control in the United States currently use IUDs. The most recently introduced hormonal IUD is the levonorgestrel intrauterine system (LNG IUS or Mirena). Worldwide, IUDs are the most inexpensive long-term birth control method available.
How an IUD Works
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The precise mechanism of the contraceptive action of IUDs is not known. Hormonal and copper IUDs work in different ways. With a copper IUD, a small amount of copper is released into the uterus. Neither type of IUD affects ovulation or the menstrual cycle. Copper IUDs may prevent sperm from being able to go into the egg by immobilizing the sperm on the way to the fallopian tubes.
With hormonal IUDs, a small amount of progestin, a hormone similar to the natural hormone progesterone, is released into the uterine lining. This hormone thickens cervical mucus and make it difficult for sperm to enter the cervix. Hormonal IUDs also slow down the growth of the uterine lining, making it inhospitable for fertilized eggs.
Medically Reviewed by a Doctor on 5/20/2014
Omnia M Samra, MD
Bryan D Cowan, MD
Francisco Talavera, PharmD, PhD
Lee P Shulman, MD
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Patient Comments & Reviews
The eMedicineHealth doctors ask about Intrauterine Devices (IUDs) for Birth Control):
Birth Control Intrauterine Devices (IUDs) - Experience
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IUDS - Side Effects
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