There are several intrauterine methods of preventing pregnancy. There are two types of coils (with and without hormones), both of which can remain in place for at least five years and can easily be removed, after which fertility returns.
A coil works on the basis of the presence of a foreign body in the uterus, which prevents the ovum from becoming implanted. With a copper coil, the copper also renders the sperm cells inactive so that they are no longer able to penetrate an ovum.
A hormone coil affects the mucus of the cervix so that the sperm cells are less able to move through it. The mucus membrane of the uterus is also less structured, making implantation very rare.
One pleasant side-effect with this method is that most women have no or a greatly-reduced menstruation. It is therefore also often prescribed in cases of heavy, painful or irregular periods.
A hormone coil can cause irregular blood loss, particularly in the first few months, but after using this method for one year, 80% of women are satisfied. About 25% no longer menstruate and about 50% still experience blood loss, but far less.