The intrauterine device (IUD) is a small plastic device that is fitted within the uterus in order to prevent pregnancy. There are now IUDs that release hormones and thus provide a form of double protection – the effect of a foreign substance in the uterus and the effects on the uterine lining of the hormones. The hormonal IUD is often referred to as the intrauterine system (IUS), as it combines two contraceptive methods, the intrauterine device and the hormone.
Various forms of IUS are available in different countries. All contain the progestin (artificial progesterone) levonorgestrel, although at different dosages. Depending on the formulation, they can be used for 3-5 years. The efficacy of hormonal IUDs in prevention of pregnancy is approximately 99%.
The hormonal IUD is inserted via the cervix in a compressed manner and opens to its full shape (similar to the letter T) inside the uterus. When open, the IUD is wider than the opening of the uterus and thus should remain in place until medically removed. Two small strings are left protruding from the cervix to allow confirmation that the device has not spontaneously slipped out. These strings also facilitate removal when desired.
The IUS works like other progesterone-only contraceptives by suppressing ovulation and altering the cervical mucus, thus preventing fertilization. In addition, the presence of a foreign body in the uterus seems to interfere with both fertilization and implantation.
Bleeding and Staining
Many women experience irregular bleeding or spotting during first three to 6 months with an IUS. Women who use this method need to be prepared for a difficult beginning, and should take precautions to avoid becoming niddah unnecessarily due to staining (see Ketamim).
Over time, however, IUS reduces the amount of bleeding experienced during menstruation by around 80% on average, and may eliminate menstruation altogether.
The IUD is reversible, presents no physical barriers to intercourse, and works primarily by preventing fertilization. Thus, it presents few halachic problems in a situation where contraception itself is permitted. Currently, most halachic authorities consider the IUD a fully permissible method.
However, in about 1% of cases, the IUD prevents implantation of the fertilized ovum, raising more serious halachic issues. Therefore, some controversy still exists.