摘要：

The duration of use of any contraceptive method is predicated on the freedom of side effects, rather than absolute efficacy. This achieved, any method would be acceptable for wide use. The experience obtained with intrauterine devices is illustrative. These have not fulfilled their original expectation because of the problem of side effects. With this method contraceptive effectiveness can be correlated with the size of the device. In order to achieve acceptable efficacy the size of the device must be relatively large which causes uterine distortion, cramps and bleeding and in a sizable percentage of the population the device must be removed.

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