Nishmat's Women’s Health and HalachaIn memory of Chaya Mirel bat R' Avraham

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Medical Background

The intrauterine device (IUD) is a small contraceptive device fitted within the uterus. It needs to be inserted and removed by a physician. Depending on the type, it can be effective for 3-10 years.

Types of IUD

There are two main types of IUD. The copper IUD is made from plastic and copper. The hormonal IUD (also known as the intrauterine system, or IUS) is a plastic device that releases synthetic progesterone. Both types of IUD are over 99% effective.

Each type comes in a range of forms, with availability differing by country. There are small variations in size, composition, hormonal formulation, and method of insertion. A T-shape is most common. In attempts to reduce irritation, Ballerine is ball-shaped, and the Gynefix (currently less widely available) has its tip embedded in the uterine wall.


The exact mechanism of the copper IUD is still not completely understood. The most recent and widely accepted theory is that it prevents fertilization by altering the environment within the uterus and fallopian tubes so that it is hostile to sperm.

The IUD was once thought to prevent implantation (i.e., the sperm and ovum unite and begin dividing but the resulting embryo does not become embedded in the uterine lining). This earlier theory appears to be accurate in only a very small minority of cases.

The IUS works like other progesterone-only contraceptives by suppressing ovulation and altering the cervical mucus, thus preventing fertilization. In addition, as above, the presence of a foreign body in the uterus seems to interfere with both fertilization and implantation. All types of IUS release the synthetic progesterone levonorgestrel, although at different dosages.

A physician inserts the IUD or IUS into the uterus through a narrow applicator tube, which is generally less than 10 mm in diameter. The IUD/IUS opens to its full shape inside the uterus. When open, the IUD/IUS is wider than the opening of the uterus and thus should remain in place until medically removed.

After insertion, the IUD/IUS requires no further action on the part of the couple. One or 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.


Intrauterine devices are considered a safe and efficacious contraceptive method. In many countries, they have become the most popular method of reversible female contraception.

Recent studies with modern copper IUDs have found no increase in tubal infertility and an overall low rate of pelvic inflammatory disease, which were of concern with some older versions.

Concerns have been raised in the past as to whether the IUD increases the incidence of ectopic pregnancy (pregnancy outside the uterus). Recent studies seem to indicate that the device does not cause ectopic pregnancies, but rather prevents uterine pregnancies more effectively than extra-uterine pregnancies.

Side Effects

Both the IUD and IUS are associated with irregular bleeding and staining, which we discuss in detail below.

Additionally, the copper IUD is often associated with heavier and/or longer menses. Some women also experience changes in the length of the menstrual cycle.

The hormonal IUS is often associated with prolonged staining. It also can have other side effects common to progesterone-only contraception, including mood changes (especially depression) and weight gain. However, as the progesterone is release locally and not taken systemically, the frequency of these side effects is believed to be less than when taken orally.

Over time, the hormonal IUS significantly reduces the quantity of menstrual bleeding, and may eliminate menstruation—and niddah—altogether.

Halachic Desirability

The IUD and IUS are reversible, present no physical barriers to intercourse, and work primarily by preventing fertilization. Thus, they present few halachic problems in a situation where contraception itself is permitted.

Most halachic authorities consider the IUD/IUS a fully permissible method. Since they prevent implantation of the fertilized ovum in about 1% of cases, there are a few authorities who view them as controversial.

The irregular bleeding and staining associated with the IUD and IUS are also a halachic consideration, since they can present halachic challenges.

Bleeding & Staining

Women who use either the IUD or the IUS need to be prepared for a difficult beginning, although the bleeding patterns of each are somewhat different. The copper IUD is more likely to cause longer or heavier periods. The hormonal IUS is more likely to cause irregular bleeding. Especially during the first months of use, women should take precautions to avoid becoming niddah unnecessarily due to staining by wearing colored underwear and by being careful with toilet paper. The degree of irregular bleeding with the IUD or IUS tends to decrease with time, and for most women reaches acceptable levels within 3-6 months.

A recent study has pinpointed Vitamin B1 as reducing staining associated with the IUD. Anecdotally, some women have found it helpful to take bioflavonoids. A physician should be consulted prior to pursuing these or other complementary treatments

Some women experience only very light bleeding while using the hormonal IUS. Bleeding that is lighter than a light period is evaluated based on the usual criteria for staining, described in our articles on stains and toilet paper.

Even if such staining occurs regularly every month, it is not automatically considered a “period” that makes a woman niddah. Here, too, the staining should be assessed based on the usual laws of stains.

A woman who is having difficulty completing the shivah neki’im with an IUD or IUS should consult with a halachic authority. When asking a question, she should be sure to mention that she has an IUD or IUS and is having difficulties with staining. She may be advised to reduce the number of bedikot or to take other steps, and will likely be encouraged to bring any questionable bedikah or stain for evaluation.

Since the IUD strings are internal, mobile, and long-term, they are not a barrier for mikveh immersion.

Insertion & Removal

There is halachic debate as to whether inserting or removing an IUD or IUS renders a woman niddah. There are two possible concerns: uterine dilation, and bleeding caused by the procedure.

Uterine dilation, even without bleeding, renders a woman niddah. Halachic authorities differ regarding the degree of dilation required. We follow the position that uterine dilation through insertion of an instrument less than 19mm in diameter does not make a woman niddah, so a standard IUD insertion or removal does not cause niddah..

A woman who follows the more stringent opinions should ask her physician about the exact degree of uterine dilation with IUD insertion or removal, since it may be greater than 4 mm.

Vaginal bleeding following IUD insertion or removal may is often considered dam makkah (bleeding from trauma), which does not make a woman niddah. In other cases, such bleeding does make her niddah.

Each case is unique, and halachic authorities differ in their approaches. Therefore, it is best for each woman to ask an individual question to her halachic authority to determine whether she will become niddah from the procedure. The following discussion follows the rulings of our current rabbinic supervisor, Rav Kenneth Auman.

Following insertion or removal: Vaginal bleeding that starts with or shortly after insertion or removal is assumed to be from the trauma of the procedure (dam makkah), and does not make a woman niddah.

Bleeding that continues for longer than a day or two, or that begins more than a day after the procedure, cannot automatically be attributed to trauma and disregarded, and typically requires an individual halachic ruling. It is especially difficult to attribute vaginal bleeding that starts 2-3 days after insertion or removal of a hormonal IUS to the procedure because of the likelihood of bleeding related to the shift in hormones.

In all these situations, the leniencies of ketamim (stains) apply to light bleeding or staining. Therefore, before having these procedures, a woman should review the halachot of stains and take precautions to avoid becoming niddah unnecessarily, such as wearing only colored underwear and being careful with toilet paper.

Both these procedures can lead to discomfort. A woman should discuss any concerns, or the possibility of taking a pain reliever in advance, with her healthcare provider.


Medically, physicians vary as to when they prefer to insert the IUD. Insertion can usually take place safely at most points of the menstrual cycle, and removal can generally be performed at any time of the cycle.

Postpartum insertion can take place within two days of delivery or after four weeks.

Halachically, if one follows the opinion that the insertion does not make one niddah, it is best to have the IUD inserted after mikveh immersion so that the mild bleeding from the procedure does not lead to confusion during the bedikot of the shivah neki’im. We would recommend insertion at least a week before any veset days and their attendant bedikot.

A woman who will have the procedure during the shivah neki’im should perform the bedikah for that day before the appointment, and then delay the following bedikah until the next day. If there is concern that bleeding from the procedure would affect bedikot beyond that point, a halachic question should be asked.

Note that a short-term contraceptive method may be required between mikveh and IUD insertion, or from mikveh until an IUS becomes effective.

This article was updated on 27 December 2022.

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All health and health-related information contained within Nishmat's Women's Health & Halacha Web site is intended to be general in nature and should not be used as a substitute for consulting with your health care professional. The advice is intended to offer a basis for individuals to discuss their medical condition with their health care provider but not individual advice. Although every effort is made to ensure that the material within Nishmat's Women's Health & Halacha Web site is accurate and timely, it is provided for the convenience of the Web site user but should not be considered official. Advice for actual medical practice should be obtained from a licensed health care professional.

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