An intrauterine device (intra meaning within, and uterine meaning of the uterus) is a birth control device also known as an IUD or a coil (this colloquialism is based on the coil-shaped design of early IUDs). It is a device placed in the uterus and is the world's most widely used and inexpensive method of reversible birth control. The device has to be fitted inside or removed from the uterus by a doctor or qualified medical practitioner. It remains in place the entire time contraception is desired (depending on the type, IUDs can usually remain effective for 2, 5 or 10 years).

Some IUDs release hormones into the womb, whereas the traditional types contain copper, which kills sperm and may also affect the cervix and womb lining, so that sperm is less likely to enter the uterus and ova are less likely to implant in the uterus lining (it is not fully known exactly how IUDs work). This latter effect means that IUDs are abortifacient (induce abortion).

The hormonal IUD is as effective as the contraceptive pill at preventing pregnancy; and the copper IUDs effectiveness ranges from 98% to over 99% depending on the brand. IUDs can not protect from STDs, and if an infection is caught whilst using and IUD it may be more likely to spread to the uterus.

Women may choose to use an IUD because the device can be left in place for years and can safely be forgotten about for long periods of time, unlike other forms of contraception. Copper IUDs may be chosen by women who wish to avoid the use of artificial hormones, which may have unpleasant short- or long-term side effects. Copper IUDs may make menstrual periods heavier or more painful in some women, especially for the first few months after they are inserted, but modern types such as the GyneFix have been designed so that they usually do not affect periods.

IUDs have remained unpopular in the USA since the "Dalkon Shield" IUD was banned after being linked to several deaths (by making women more likely to contract uterine infections which can occasionally be fatal) and this was sensationalised in the press. Modern IUDs, however, are much safer and complications are very rare.

Intrauterine devices can be used as "emergency contraception" to prevent pregnancy up to 7 days after unprotected sexual intercourse; this is an alternative to the morning-after pill - the IUD is much more effective than the morning-after pill at preventing pregnancy after unprotected sex.

See also

• Intra vas device

External links

• Planned Parenthood: Understanding IUDs