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.
At present, there are two forms of IUS marketed in the United States. One is known as Mirena and the other is known as Skyla. They both contain the progestin (artificial progesterone) levonorgestrel although at different dosages. The former can be used for up to five years and the latter for up to three year. In other countries such as the UK, there is an additional IUS that is even smaller and releases a lower dose of levonorgestrel, known as Jaydess. This is also effective for three years. The efficacy of all the 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 different theories as to the mechanism of action and past health concerns have had implications for the halachic desirability of this form of contraception. If the IUD primarily prevents fertilization, then it presents few halachic problems in a situation where contraception itself is permissible. On the other hand, if the IUD prevents implantation of the fertilized ovum, then the more serious issue of abortion is raised. Furthermore, health risks are always a halachic concern. Currently, the IUD is considered by many rabbis to be the method of birth control second in line after hormonal contraception, although controversy does exist. There is no difference in halachic desirability between the hormonal and non hormonal IUD.