Doctors are still not entirely sure how the intra-uterine device (IUD or IUCD), often called the coil, works. They believe that it is one of the methods which discourage implantation of a fertilized egg. Early IUDs were made of metal but current devices are usually plastic, or plastic and copper wire. The copper wire appears to improve the efficiency of the device, so that it can be made even smaller and still function. However, whereas plastic-only devices can be left in place for many years, a plastic and copper IUD must be changed about every three years.
The IUD has the advantage that once installed it gives protection against pregnancy immediately. The safety rate is about 98 per cent. It can even be inserted in order to prevent pregnancy some days after unprotected intercourse has occurred. Another advantage is that on removal of the IUD, the woman is able to become pregnant immediately.
An IUD should be inserted by a trained doctor. The woman may experience discomfort, resembling menstrual cramps, during and after the procedure. The more experienced doctor and relaxed the patient, the less likely this is to happen. Women who have not had pregnancy or those having multiple partners are slowly more at risk of suffering a pelvic infection with an IUD and there is greater risk of ectopic pregnancy. Also, since the device can encourage heavy periods, women with already troublesome periods would have been advised to try another method. Another disadvantage is that the device may be expelled by uterine contractions. If this occurs unnoticed the woman may uncorrectly think intercourse is safe. Apart from simply checking that it is still in place by feeling the thread attached to it in the vagina, no further contraceptive care is needed.
Spermicides are chemical preparations that kill sperm. They are not in themselves reliable opponents, but give added protection when used with other methods. They come in jelly or cream form, in a tube or as a foam from an aerosol. They are also available as pessaries. Spermicidal cream or jelly is spread over a diaphragm or condom before insertion. The effective life of the spermicide is about three hours, so if intercourse does not take place in that time, a further application of spermicide should be made, either the jelly or cream using an applicator, or in the pessary form. The spermicide should also be 'topped up' in this way if sex takes place more than once.